The VisAD Java Component Library
Developers Guide
7 April 2000
1. Introduction
1.1 System Availability
1.2 Package Structure
1.3 Authorship, Copyright, History and Support
2. Overview
2.1 A Very Simple Application Example
2.2 A Simple Application Example
2.3 Flexible Design by Reduction to Elements
2.4 The Value of Integrated Metadata
2.5 Toolkit for Designing Interaction Techniques
3. Data Model
3.1 MathTypes
3.1.1 RealType Constructors
3.1.2 TextType Constructor
3.1.3 TupleType Constructor
3.1.4 RealTupleType Constructors
3.1.5 FunctionType Constructor
3.1.6 SetType Constructor
3.1.7 MathType Methods
3.1.8 ScalarType Methods
3.1.9 RealType Methods
3.1.10 TupleType Methods
3.1.11 RealTupleType Methods
3.1.12 FunctionType Methods
3.1.13 SetType Methods
3.1.14 Application Example: Synthesizing MathTypes
3.1.15 Application Example: Analyzing MathTypes
3.2 Data Class Hierarchy
3.2.1 Real Constructors
3.2.2 Text Constructor
3.2.3 Tuple Constructors
3.2.4 RealTuple Constructors
3.2.5 Field Constructors
3.2.6 Data Methods
3.2.7 Real Methods
3.2.8 Text Methods
3.2.9 Tuple Methods
3.2.10 RealTuple Methods
3.2.11 Function Methods
3.2.12 Field Methods
3.2.13 FieldImpl Method
3.2.14 Application Example: Synthesizing Fields
3.3 Units
3.3.1 Unit Methods
3.3.2 SI Variables
3.3.3 BaseUnit Methods
3.3.4 CommonUnit Variables
3.4 CoordinateSystems
3.4.1 CoordinateSystem Constructors
3.4.2 CoordinateSystem Methods
3.5 Sets
3.5.1 Defining Interpolation Algorithms by Extending the Set Class
3.5.2 The Delaunay Class for Irregular Sets
3.5.3 Set Constructors
3.5.3.1 DoubleSet and FloatSet Constructors
3.5.3.2 LinearSet Constructors
3.5.3.3 IntegerSet Constructors
3.5.3.4 GriddedSet Constructors
3.5.3.5 IrregularSet Constructors
3.5.3.6 ProductSet and UnionSet Constructors
3.5.4 Set Methods
3.5.5 SimpleSet Methods
3.5.6 Delaunay Constructors
3.6 ErrorEstimates
3.6.1 ErrorEstimate Constructors
3.7 AuditTrails
3.8 Missing Data
3.9 FlatFields - Data Operations and Efficiency
3.9.1 FlatField Constructors
3.9.2 FlatField Methods
3.10 Immutable Data
3.11 DataReferences
3.11.1 DataReference Constructors
3.11.2 DataReference Methods
3.12 Application Example: Arrays versus VisAD Functions
3.12.1 Subtracting Images as Pixel Arrays in C
3.12.2 Subtracting Images as Pixel Arrays in VisAD
3.12.3 Subtracting Images as Functions in VisAD
4. Visualization
4.1 ScalarMaps and DisplayRealTypes
4.1.1 Common Sense and ScalarMaps
4.1.2 DisplayRealType and DisplayTupleType Constructors
4.1.3 DisplayRealType Methods Useful for Extending DataRenderer
4.1.4 ScalarMap and ConstantMap Constructors
4.1.5 Generally Useful ScalarMap Methods
4.1.6 ScalarMap Methods Useful for Extending DataRenderer
4.1.7 ConstantMap Methods
4.1.8 ScalarMapListener Methods
4.1.9 ScalarMapEvent Methods
4.1.10 Application Example: ScalarMaps and ConstantMaps
4.2 DataRenderers and DisplayRenderers
4.2.1 Java3D DataRenderer and DisplayRenderer Constructors
4.2.2 Java2D DataRenderer and DisplayRenderer Constructors
4.2.3 DataRenderer Methods
4.2.4 DisplayRenderer Methods
4.2.5 DisplayRendererJ2D Method
4.2.6 DisplayRendererJ3D Method
4.3 Controls
4.3.1 Control Methods
4.3.2 ControlListener Methods
4.3.3 ControlEvent Methods
4.3.4 AnimationControl Methods
4.3.5 ColorControl Methods
4.3.6 ColorAlphaControl Methods
4.3.7 ContourControl Methods
4.3.8 FlowControl Methods
4.3.9 GraphicsModeControl Methods
4.3.10 ProjectionControl Methods
4.3.11 RangeControl Methods
4.3.12 ShapeControl Methods
4.3.13 ValueControl Methods
4.3.14 TextControl Methods
4.4 Mouse Interactions and Direct Manipulation
4.4.1 Changing Data Values by Re-drawing Data Depictions
4.4.2 Application Example: Interactive Scaling
4.5 ShadowTypes
4.6 The Display Class
4.6.1 Java3D Display Constructors
4.6.2 Java2D Display Constructors
4.6.3 Display Methods
4.6.4 DisplayImpl Methods
4.6.5 RemoteDisplayImpl Methods
4.6.6 DisplayListener Methods
4.6.7 DisplayEvent Methods
4.7 Shapes
4.7.1 VisADGeometryArray Shapes
4.7.2 The PlotText.render_label Method
4.8 RemoteSlaveDisplays
4.8.1 RemoteSlaveDisplayImpl Constructor
4.8.2 RemoteSlaveDisplayImpl Method
5. Computational Cells
5.1 Cell Constructors
5.2 Cell Methods
5.3 ActionImpl Methods
6. Distributed Computing
6.1 Distributed Computing Guidelines and Cautions
6.2 Connecting to Remote Machines
6.2.1 RemoteServerImpl Constructors
6.2.2 RemoteServer Methods
6.2.3 RemoteServerImpl Methods
6.3 Application Example: Collaborative Direct Manipulation
6.4 Collaborative Displays
7. File Format and Data Form Adapters
7.1 Extracting Metadata From Data Objects Returned by Data Form Adapters
7.2 General Design of Data Form Adapters
7.2.1 Form Methods
7.3 FITS Adapter
7.4 netCDF Adapter
7.5 HDF-EOS Adapter
7.6 GIF / JPEG Adapter
7.7 Vis5D Adapter
7.8 McIDAS Adapter
7.9 VisAD Adapter (serialized Java objects)
7.10 HDF-5 Adapter
8. User Interfaces
8.1 VisAD User Interface Classes
8.1.1 VisADSlider Constructor
8.1.2 LabeledRGBWidget and LabeledRGBAWidget Constructors
8.1.3 LabeledRGBWidget and LabeledRGBAWidget Methods
8.1.4 SelectRangeWidget Constructor
8.1.5 AnimationWidget Constructor
8.1.6 ContourWidget Constructor
8.1.7 GMCWidget Constructor
9. Simplified Classes for Using VisAD
10. The VisAD Spread Sheet
10.1 Spread Sheet Classes
10.2 Features of the SpreadSheet User Interface
10.2.1 Basic Commands
10.2.2 Menu Commands
10.2.2.1 File Menu
10.2.2.2 Edit Menu
10.2.2.3 Setup Menu
10.2.2.4 Display Menu
10.2.2.5 Options Menu
10.2.3 Toolbars
10.2.3.1 Main Toolbar
10.2.3.2 Formula Toolbar
10.2.3.2.1 Description
10.2.3.2.2 How To Enter Formulas
10.2.3.2.3 Linking to External Java Code
10.2.3.2.4 Examples of Valid Formulas
10.2.4 Remote Collaboration
10.2.4.1 Creating a SpreadSheet RMI server
10.2.4.2 Sharing individual SpreadSheet cells
10.2.4.3 Cloning entire SpreadSheets
10.3 Future Plans
11. Extending the VisAD Java Class Library
12. Application Examples
12.1 The DisplayTest Class
12.2 Visualizing the HSV Color CoordinateSystem
12.3 Collaborative GOES Satellite Sounding Analysis
12.4 A Steerable Shallow Fluid Model
12.5 A Simple Weather Simulation Visualizer
12.6 Image Animation Using Java2D
12.7 Earth Topography and Bathymetry
13. Caveats and Future Plans
13.1 JavaBean Components
14. For More Information and Help with Problems
15. References
Appendix A Constraints on ScalarMaps and MathTypes
Appendix B The GoesCollaboration Application Source Code
http://www.ssec.wisc.edu/~billh/visad.htmlVisAD requires Java 1.2. VisAD displays are generated using either Java2D (included in Java 1.2) or Java3D. More information about these is available at:
http://java.sun.com/
visad - the core VisAD package visad.cluster - large data distributed on clusters visad.collab - collaborative displays visad.java3d - Java3D displays for VisAD visad.java2d - Java2D displays for VisAD visad.python - Python support for VisAD visad.browser - JDK 1.1 browser interface to VisAD visad.ss - the VisAD Spread Sheet visad.formula - formula parser visad.matrix - matrix operations via JAMA visad.math - FFT and histogram operations visad.util - VisAD user interface utilities visad.data - VisAD data format adapters visad.data.in - support for read-only VisAD adapters visad.data.units - units database and parsing visad.data.dods - VisAD - DODS server adapter visad.data.fits - VisAD - FITS file adapter visad.data.netcdf - VisAD - netCDF file adapter visad.data.netcdf.units - units parser for netCDF adapter visad.data.netcdf.in - data input for netCDF adapter visad.data.netcdf.out - data output for netCDF adapter visad.data.hdfeos - VisAD - HDF-EOS file adapter visad.data.hdfeos.hdfeosc - native interface to HDF-EOS visad.data.gif - VisAD - GIF / JPEG file adapter visad.data.ij - VisAD adapter for image files via ImageJ visad.data.jai - VisAD adapter for image files via JAI visad.data.qt - VisAD - QuickTime file adapter visad.data.tiff - VisAD - TIFF file adapter visad.data.text - VisAD - ASCII file adapter visad.data.vis5d - VisAD - Vis5D file adapter visad.data.mcidas - VisAD - McIDAS file adapter visad.data.biorad - VisAD - Biorad file adapter visad.data.amanda - VisAD - F2000 file adapter & viewer visad.data.hdf5 - VisAD – HDF-5 file adapter visad.data.hdf5.hdf5objects - helper for HDF-5 adapter visad.data.visad - VisAD (serial object) file adapter visad.data.visad.object - VisAD (serial object) file adapterThe following packages are distributed with VisAD:
HTTPClient - complete http client library nom.tam.fits - Java FITS file binding nom.tam.util - Java FITS file binding nom.tam.test - Java FITS file binding ucar.netcdf - Java netCDF file binding ucar.multiarray - Java netCDF file binding ucar.util - logging functions for servers ucar.tests - test Java netCDF file binding dods.dap - DODS server core classes dods.dap.parser - JavaCC generated DODS paersers dods.dap.server - DODS servers dods.util - utility classes for DODS gnu.regexp - GNU regular expressions edu.wisc.ssec.mcidas - Java McIDAS file binding edu.wisc.ssec.mcidas.adde - Java McIDAS file binding ij - ImageJ system package ij.gui - ImageJ system package ij.io - ImageJ system package ij.measure - ImageJ system package ij.plugin - ImageJ system package ij.plugin.filter - ImageJ system package ij.plugin.frame - ImageJ system package ij.process - ImageJ system package ij.text - ImageJ system package ij.util - ImageJ system package ncsa.hdf.hdf5lib - Java HDF-5 file binding ncsa.hdf.hdf5lib.exceptions – Java HDF-5 file binding visad.paoloa - GOES satellite analysis visad.paoloa.spline - spline fitting visad.aune - shallow fluid model visad.benjamin - Milky Way galaxy model visad.rabin - rainfall estimation spread sheet visad.jmet - JMET – Java meteorology visad.meteorology - classes useful for meteorology visad.bom - classes for ABOM visad.aeri - classes for AERI data visad.georef - classes for georeferencing visad.install - cluster installer for VisAD-in-a-boxThe VisAD source distribution also includes a directory visad/examples that contains classes with the default package (i.e., no package statement).
VisAD is constantly being updated to fix bugs and add features and we don't even try to track all of these changes with VisAD version numbers. Rather, a file named 'DATE' is included in distribution jar files that gives the date and time the distribution file was created. We will change VisAD version numbers as new features accumulate.
Bill Hibbard - SSEC (contact author: hibbard@facstaff.wisc.edu) Steve Emmerson - Unidata Curtis Rueden - SSEC Tom Rink - SSEC Dave Glowacki - SSEC Tom Whittaker - SSEC Tommy Jasmin - SSEC Don Murray - Unidata Jeff McWhirter - Unidata Nick Rasmussen - SSEC Peter Cao - NCSA James Kelly - ABOM Andrew Donaldson - ABOM Doug Lindholm - NCAR Sylvain Letourneau - Canadian NRCThe following people made substantial intellectual contributions to the design:
John Anderson - SSEC Dave Fulker - Unidata Russ Rew - Unidata Glen Davis - UnidataVisAD is freely available including source code. It is protected by copyright statements embedded in the source code and in the NOTICE, LICENSE and COPYING files distributed with the source code.
The VisAD Java class library is actually VisAD version 2.0. VisAD versions 1.0 and 1.1 were written in C by Bill Hibbard, Brian Paul (of SSEC) and Andre Battaiola (while visiting SSEC from INPE/CPTEC in Brazil) [8, 9], with substantial intellectual contributions from Charles Dyer of the UW Computer Sciences Dept.
VisAD has adopted the UD Units library developed by Steve Emmerson of Unidata. [http://www.unidata.ucar.edu/packages/udunits/index.html].
VisAD borrows design ideas and code from the Vis5D system for interactive visualization of numerical simulations of weather and other environmental phenomena [6, 9, 10]. Vis5D was written in C by Bill Hibbard, Johan Kellum (of SSEC), Brian Paul, Andre Battaiola, Dave Santek (of SSEC) and Marie-Francoise Voidrot-Martinez (while visiting SSEC from METEO France).
Vis5D grew out of the 4-D McIDAS system [5, 6], which was part of Verner Suomi's McIDAS system for visualizing data from his weather satellites. The 4-D McIDAS was the 3-D (plus animation) analog of Tom Whittaker's 2-D graphics subsystem of McIDAS, which was the first interactive weather graphics system.
The development of this software has been supported by NASA, EPA, NSF (via Unidata and NCSA), NOAA, ARPA and DOE. We especially want to thank Joe Bredekamp of NASA, Cliff Jacobs of NSF and Larry Smarr of NCSA for their support of the Java VisAD. We are also grateful to the Charles and Mamie van Doren Foundation for their support.
The World Wide Web has created a shared network of generally passive text and image information. Distributed objects enabled by Java RMI will make this shared network much more active; that is, a network that includes execution threads. The VisAD system's general data model and thorough use of Java RMI provide a way to build a shared, active network of scientific data, displays and computations. This network could:
// import needed classes
import visad.*;
import visad.util.DataUtility;
import visad.java3d.DisplayImplJ3D;
import visad.data.netcdf.Plain;
import java.rmi.RemoteException;
import java.io.IOException;
import java.awt.*;
import javax.swing.*;
public class VerySimple {
// type 'java VerySimple' to run this application
public static void main(String args[])
throws VisADException, RemoteException, IOException {
// create a netCDF reader
Plain plain = new Plain();
// read an image sequence from a netCDF into a data object
DataImpl image_sequence = plain.open("images.nc");
// create a display for the image sequence
DisplayImpl display = DataUtility.makeSimpleDisplay(image_sequence);
// create JFrame (i.e., a window) for the display
JFrame frame = new JFrame("VerySimple VisAD Application");
// link the display to the JFrame
frame.getContentPane().add(display.getComponent());
// set the size of the JFrame and make it visible
frame.setSize(400, 400);
frame.setVisible(true);
}
}
The VerySimple.java program is included in the visad/examples directory of
the VisAD source distribution. To run it you also need to download and
uncompress the images.nc file from:
ftp://ftp.ssec.wisc.edu/pub/visad-2.0/images.nc.Zinto your visad/examples directory.
UI slider ---> DataReference ---> Cell ---> DataReference ---> Display
| |
| |
Real hour Field image
This diagram corresponds to the following simple application code:
// import needed classes
import visad.*;
import visad.java3d.DisplayImplJ3D;
import visad.util.VisADSlider;
import visad.data.netcdf.Plain;
import java.rmi.RemoteException;
import java.io.IOException;
import java.awt.*;
import java.awt.event.*;
import java.awt.swing.*;
public class Simple {
// type 'java Simple' to run this application
public static void main(String args[])
throws VisADException, RemoteException, IOException {
// create a DataReference for an image
final DataReference image_ref = new DataReferenceImpl("image");
// create a netCDF reader
Plain plain = new Plain();
// open a netCDF file containing an image sequence and adapt
// it to a Field Data object
final Field image_sequence = (Field) plain.open("images.nc");
// create a Display using Java3D
DisplayImpl display = new DisplayImplJ3D("image display");
// extract the type of image and use
// it to determine how images are displayed
FunctionType image_sequence_type =
(FunctionType) image_sequence.getType();
FunctionType image_type =
(FunctionType) image_sequence_type.getRange();
RealTupleType domain_type = image_type.getDomain();
// map image coordinates to display coordinates
display.addMap(new ScalarMap((RealType) domain_type.getComponent(0),
Display.XAxis));
display.addMap(new ScalarMap((RealType) domain_type.getComponent(1),
Display.YAxis));
// map image brightness values to RGB (default is grey scale)
display.addMap(new ScalarMap((RealType) image_type.getRange(),
Display.RGB));
// link the Display to image_ref
// display will update whenever image changes
display.addReference(image_ref);
// create a DataReference and RealType for an 'hour' value
final DataReference hour_ref = new DataReferenceImpl("hour");
RealType hour_type =
(RealType) image_sequence_type.getDomain().getComponent(0);
// and link it to a slider
VisADSlider slider = new VisADSlider("hour", 0, 3, 0, 1.0,
hour_ref, hour_type);
// create a Cell to extract an image at 'hour'
// (this is an anonymous inner class extending CellImpl)
Cell cell = new CellImpl() {
public void doAction() throws VisADException, RemoteException {
// extract image from sequence by evaluating image_sequence
// Field at 'hour' value
image_ref.setData(image_sequence.evaluate(
(Real) hour_ref.getData()));
}
};
// link cell to hour_ref to trigger doAction whenever
// 'hour' value changes
cell.addReference(hour_ref);
// create JFrame (i.e., a window) for display and slider
JFrame frame = new JFrame("Simple VisAD Application");
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {System.exit(0);}
});
// create JPanel in JFrame
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
panel.setAlignmentY(JPanel.TOP_ALIGNMENT);
panel.setAlignmentX(JPanel.LEFT_ALIGNMENT);
frame.getContentPane().add(panel);
// add slider and display to JPanel
panel.add(slider);
panel.add(display.getComponent());
// set size of JFrame and make it visible
frame.setSize(500, 600);
frame.setVisible(true);
}
}
Creating the DataReferences for 'hour' and 'image' and linking them to the
VisADSlider and Cell is simple. Creating the Display and linking it to the
'image' DataReference is also simple. Setting up the JFrame and JPanel are not
too difficult and really independent of VisAD. The only complex part of this
application is extracting the image's type information for use in setting up the
Display. Every VisAD Data object has a MathType that describes its basic
structure. Every real number value occurring in a complex Data object has a
RealType, a subclass of MathType, that includes a name like "latitude", "time"
or "temperature". The code in our simple application extracts the RealTypes
from the MathType of the image so that it can define different display roles for
the real number values occurring in the image. The image Data object is
interpreted as a function that maps pixel locations into pixel brightnesses, and
its MathType, denoted image_type, is a FunctionType that includes MathTypes for
the function's domain and range. The image_type can be diagrammed as:
FunctionType (image_type)
/ \
function domain function range
RealTupleType RealType (brightness)
/ \ |
RealType (line) RealType (element) |
| | |
| | |
v v v
XAxis YAxis RGB
Note that the bottom of the diagram includes the scalar mappings of image_type's
RealType components to DisplayRealTypes: XAxis, YAxis and RGB (RGB indicates a
pseudo color lookup table that maps brightness values to red, green and blue
values).The image_sequence Data object is treated as a function from time (hours) to images, so its MathType, denoted image_sequence_type, is also a FunctionType that can be diagrammed as:
FunctionType (image_sequence_type)
/ \
function domain function range
RealType (hour) FunctionType (image_type)
/ \
function domain function range
RealTupleType RealType (brightness)
/ \
RealType (line) RealType (element)
Note that the image_type diagram is replicated in the range of this
image_sequence_type diagram.The call to the getType method of image_sequence returns its MathType, and then the calls to the getRange, getDomain and getComponent methods are used to parse the tree structure of the MathType to extract the RealTypes at the leaves of the tree. These RealTypes are then mapped to display coordinates such as Display.XAxis and Display.YAxis, and to display colors such as Display.RGB, using the ScalarMap constructors that are attached to the Display via its addMap method.
Note that image_sequence is treated as a function from a set of hour values to a set of images, and the evaluate method of image_sequence evaluates this function at an hour value and returns an image. Thus the doAction method of our computational Cell applies the evaluate method of image_sequence to an hour value to extract an image. Note also that image_sequence is declared as a Field, which is the VisAD class for functions represented by finite samplings.
In order to run the Simple application you need to download and uncompress the netCDF file "images.nc" from:
ftp://ftp.ssec.wisc.edu/pub/visad-2.0/images.nc.ZResponse may be sluggish due to a problem with threads in early versions of Java3D. We should point out that the logic of this simple application, interactively selecting and displaying an image from an image sequence, can be implemented more simply and with faster response in a VisAD Display by mapping the "hour" RealType to Display.SelectValue. However, the Simple application is a nice illustration of how Data, DataReference, UI, Display and Cell objects can be linked together.
Section 12.3 describes a more complex application that creates a network of linked Data, DataReference, Display, Cell and UI objects distributed around the network to support collaboration among users at geographically remote locations. This application also includes direct manipulation Displays, where users change Data values by re-drawing their depictions. Appendix B is a complete source code listing of this application.
While the application described in Section 12.3 is more complex than the one presented here, it is still specific to a particular scientific problem. VisAD can be used to build much more flexible and generic applications. It would not be difficult to construct a generic spread sheet consisting of an array of Displays with one Data object per Display. UI components could let users add new Displays as needed and define the source of Data as: 1) a file, 2) direct manipulation in the Display, or 3) a mathematical expression involving Data objects in other Displays. VisAD could also be used as the basis for implementing a data flow system, or an interpreted numerical programming language.
The integration of metadata could allow a developer to define a sophisticated type for 2-D image data as finite samplings of continuous functions from 2-D pixel locations, such as (line, element) or (latitude, longitude), to one or more pixel radiances. Image metadata may include units for location and radiance values (e.g., radians or degrees for latitude and longitude locations), sampling topologies and geometries for pixel locations (most images have rectangular topologies, rectangular geometries in (line, element) locations but curvilinear geometries in (latitude, longitude) locations), coordinate systems for pixel locations (images with (line, element) locations may specify mathematical transformations to (latitude, longitude) locations), missing radiance indicators, and error estimates for pixel radiances and locations. Developers also have the option to ignore most of these types of metadata, and implement images as simple arrays without units, coordinate transformations, missing data or error estimates, and sampled on rectangular integer lattices (i.e., pixels are addressed by integer line and element indices, much as they are in Fortran or C arrays).
The VisAD display model offers a similar reductionist approach. Developers define displays for complex numerical data objects in terms of mappings (the ScalarMap class) from their primitive real number elements (the RealType class) to the conceptual elements of displays (the DisplayRealType class). Developers can also attach various types of display metadata and interactive controls to these mappings. Developers may even define new kinds of display elements by defining new DisplayRealTypes. This is described in detail in Section 4.
Designing VisAD data types and displays is similar to designing database schemas and views. In fact, most of the differences between VisAD data types and database schemas can be traced to the fact that databases model discrete entities while numerical data are discrete approximations to continuous entities.
VisAD's reduction to elements is very powerful for adapting to new applications, but, like database schema design, can also be a challenge. The power comes from providing a context in which developers can answer questions like "What is the nature of an image?" However, an end user who merely wants to display an image should not have to first answer such questions. Thus VisAD user interfaces should present choices to end users in higher-level terms such as images, grids and tables. Of course, it is possible to build user interfaces for VisAD that do defer such questions to end users, in order to give them the full power of the data model.
We also anticipate the development of intermediate class libraries between the core VisAD system and end user interfaces, which define higher-level application-specific data classes such as images, grids and tables. The methods of these higher-level data classes can encapsulate metadata manipulation in terms of higher-level data operations, including display methods that encapsulate manipulation of ScalarMaps from RealTypes to DisplayRealTypes. Such intermediate class libraries may simplify the task for those developing user interfaces for end users.
Section 3.12 uses code examples to illustrate how VisAD can be used for simple array operations like those used in the C programming language, but can also be used for high-level operations on arrays of data that integrate metadata.
Users who want to control all aspects of their computations may do so by explicitly manipulating and extending the VisAD metadata classes. Note in particular Section 3.3 on Units, 3.4 on CoordinateSystems, and Section 3.5.1 on Defining Interpolation Algorithms by Extending the Set Class.
As the Internet enables greater data sharing among scientists, it increases the problems associated with metadata and file format differences among scientists. Metadata integration in a common data model is an important tool for addressing these problems, both for those users who want to ignore metadata and those who want to control metadata.
Once the necessary graphics speed is attained for interactive 3-D rotation, it can be exploited for all sorts of other interaction modes, such as dragging plane slices and other specialized graphics through data volumes, selecting various combinations of fields to visually compare, animating time dynamics, editing color maps, etc. VisAD supports all of these 'ordinary' graphical interaction modes when used with sufficiently fast graphics hardware.
When computations can also be done with fast response times, they may be coupled with interactive graphics to create an interaction mode known as 'computational steering'. By allowing Data, computational Cells, Displays and user interface components to be connected flexibly, VisAD supports computational steering interactions.
Beyond ordinary graphical interactions and computational steering, VisAD is designed to support a number of more sophisticated graphical interaction modes. These include:
Data objects all have a class in the class hierarchy under Data, and all define a hierarchical composition of complex Data objects from primitive Data objects. The primitive (scalar) Data classes are Real and Text. A Real object contains a real number value (i.e., a member of R, the set of all real numbers) represented by a Java double. A Text object contains a text string. Complex hierarchical Data objects are built from these primitives using the Tuple, Set and Function classes. A Tuple object contains a set of components whose number, sequence and type are fixed by the MathType of the Tuple. A Set object represents a set of points in an n-dimensional real vector space (denoted by R^n). There are a great variety of ways of representing such Sets, as described in Section 3.5. Note that a Tuple with n Real components is a RealTuple and represents a single point in R^n. A Function object represents a function from R^n to values of some specific type. Field is the subclass of Function for functions represented by finite sets of samples of function values (for example, a satellite image samples a continuous radiance function at a finite set of pixel locations). The Data classes implement methods for various binary and unary mathematical operations (e.g., add, multiply, sqrt), as well as specialized operations such as Function evaluation and Tuple component access. The Data class hierarchy is described in more detail in Section 3.2.
Data objects include metadata defined by the classes: MathType, Unit, CoordinateSystem, Set (function domain sampling), ErrorEstimate and AuditTrail, as well as missing data indicators. The details of these different forms of metadata are described in Sections 3.1 and 3.3 - 3.8. Metadata are integrated into mathematical and visualization operations. For example Unit conversions and CoordinateSystem transforms are done implicitly as needed in Data operations.
MathType
ScalarType
RealType
TextType
TupleType
RealTupleType
SetType
FunctionType
The starting point for any new application of VisAD is defining a set of
MathTypes for the Data objects involved. This set of MathTypes provides a
context for defining metadata, data displays, and data analysis operations.
This is similar to the way that database schemas provide a context for defining
database applications. Developers using the VisAD class library can think about
MathTypes using the following shorthand syntax:
MathType := ScalarType | TupleType | SetType | FunctionType ScalarType := RealType | TextType RealType := name TextType := name TupleType := ( MathType , MathType , ..., MathType ) TupleType := RealTupleType RealTupleType := ( RealType , RealType , ..., RealType ) SetType := set ( RealTupleType ) FunctionType := ( RealTupleType -> MathType ) FunctionType := ( RealType -> MathType )where TupleType and RealTupleType each have at least one component. For example, a satellite image of Earth may be a finite sampling of a continuous function with MathType:
( (latitude, longitude) ->
(radiance_channel_1, ..., radiance_channel_N) )
The output of a weather model may be described using the MathType:
( time -> ( (latitude, longitude, altitude) ->
(temperature, pressure, dewpoint, wind_u, wind_v, wind_w) ) )
And a set of map boundaries may be described using the MathType:
set ( (latitude, longitude) )Note that the prettyString method of MathType returns a String with this shorthand notation for any VisAD MathType. The static stringToType method of MathType takes a String argument, which is assumed to be in this shorthand notation, and returns the corresponding MathType (of course, MathTypes returned by stringToType do not include any non-null default Units, CoordinateSystems or Sets).
MathTypes are a form of metadata that describe data organization. For example, weather model output are often stored in files as independent 2-D grids, where any higher-level organization must be deduced by comparing the metadata associated with each grid. MathTypes provide a way to explicitly document such higher-level data organizations.
Every scalar (i.e., primitive) value occurring in a Data object is associated with a named ScalarType occurring in the Data object's MathType. These names are used to control how the Data object is displayed, as described in Section 4.1.
Some MathTypes include default values for various kinds of metadata, including Units (see Section 3.3), CoordinateSystems (see Section 3.4), and samplings (see Section 3.5). Although these defaults may be over-ridden for Data values, the defaults define equivalence classes of convertible Units and CoordinateSystems among Data values with the same MathTypes, with convertibility enforced by the system. Note that application developers may opt out of Units, CoordinateSystems and any other form of metadata by setting that form of metadata to null in MathType and Data object constructors (however, developers may not opt out of MathTypes and Field samplings, which are mandatory).
MathType is abstract and serializable. A MathType object can only be local (see Section 6 for more information). Its subclasses are all immutable.
/** name of type (two RealTypes are equal if their names are equal);
default Unit for values of this type and may be null; default Set
used when this type is a FunctionType domain and may be null */
public RealType(String name, Unit default_unit, Set default_set)
throws VisADException;
/** name of type (two RealTypes are equal if their names are equal);
default Unit and Set are null */
public RealType(String name) throws VisADException;
/** name of type (two TextTypes are equal if their names are equal) */ public TextType(String name) throws VisADException;
/** array of component types */ public TupleType(MathType[] types) throws VisADException;
/** array of component types;
default CoordinateSystem for values of this type (including
Function domains) and may be null; default Set used when this
type is a FunctionType domain and may be null */
public RealTupleType(RealType[] types,
CoordinateSystem default_coordinate_system,
Set default_set) throws VisADException;
/** construct a RealTupleType with one component */
public RealTupleType(RealType a,
CoordinateSystem default_coordinate_system,
Set default_set) throws VisADException;
/** construct a RealTupleType with two components */
public RealTupleType(RealType a, RealType b,
CoordinateSystem default_coordinate_system,
Set default_set) throws VisADException;
/** construct a RealTupleType with three components */
public RealTupleType(RealType a, RealType b, RealType c,
CoordinateSystem default_coordinate_system,
Set default_set) throws VisADException;
/** construct a RealTupleType with four components */
public RealTupleType(RealType a, RealType b, RealType c, RealType d,
CoordinateSystem default_coordinate_system,
Set default_set) throws VisADException;
/** array of component types;
default CoordinateSystem and Set are null */
public RealTupleType(RealType[] types) throws VisADException;
/** construct a RealTupleType with one component */
public RealTupleType(RealType a) throws VisADException;
/** construct a RealTupleType with two components */
public RealTupleType(RealType a, RealType b) throws VisADException;
/** construct a RealTupleType with three components */
public RealTupleType(RealType a, RealType b, RealType c)
throws VisADException;
/** construct a RealTupleType with four components */
public RealTupleType(RealType a, RealType b, RealType c, RealType d)
throws VisADException;
/** domain must be a RealType or a RealTupleType;
range may be any MathType */
public FunctionType(MathType domain, MathType range)
throws VisADException;
/** domain must be a RealType or a RealTupleType */ public SetType(MathType domain) throws VisADException;
/** returns a missing Data object for any MathType */
public Data missingData() throws VisADException;
/** return a String that indents complex MathTypes
for human readability */
public String prettyString();
/** return an array of ScalarMaps that is an "intuitive"
guess at a good way to visualize this MathType;
returns null if it can't make a good guess */
public ScalarMap[] guessMaps(boolean threeD);
/** ScalarTypes are equal if they have the same name;
TupleTypes are equal if their components are equal;
FunctionTypes are equal if their domains and ranges
are equal */
public boolean equals(Object obj);
/** this is useful for determining compatibility of
Data objects for binary mathematical operations;
any RealTypes are equal; any TextTypes are equal;
TupleTypes are equal if their components are equal;
FunctionTypes are equal if their domains and ranges
are equal */
public boolean equalsExceptName(MathType type);
/** create a MathType from its string represnetation;
essentially the inverse of the prettyString method */
public static MathType stringToType(String s) throws VisADException;
public String getName();
/** return any RealType constructed in this JVM with name,
or null */
public static RealType getRealTypeByName(String name);
/** get default Unit */
public Unit getDefaultUnit();
/** get default Set*/
public Set getDefaultSet();
/** this is a violation of MathType immutability to allow a
a RealType to be an argument (directly or through a
SetType) to the constructor of its default Set;
this method throws an Exception if getDefaultSet has
previously been invoked */
public void setDefaultSet(Set set) throws VisADException;
/** return number of components */
public int getDimension();
/** return component for index between 0 and getDimension() - 1 */
public MathType getComponent(int index) throws VisADException;
/** return index of first component with type;
if no such component, return -1 */
public RealType getIndex(MathType) throws VisADException;
/** return index of first RealType component with name;
if no such component, return -1 */
public RealType getIndex(String name) throws VisADException;
/** get default Units of RealType components */
public Unit[] getDefaultUnits();
/** get default CoordinateSystem */
public CoordinateSystem getCoordinateSystem()
/** get default Set*/
public Set getDefaultSet();
/** this is an unavoidable violation of MathType immutability -
a RealTupleType must be an argument (directly or through a
SetType) to the constructor of its default Set;
this method throws an Exception if getDefaultSet has
previously been invoked */
public void setDefaultSet(Set set) throws VisADException;
/** if the domain passed to constructor was a RealType,
getDomain returns a RealTupleType with that RealType
as its single component */
public RealTupleType getDomain();
public MathType getRange();
/** if the domain passed to constructor was a RealType,
getDomain returns a RealTupleType with that RealType
as its single component */
public RealTupleType getDomain();
// construct RealType components for grid coordinates
RealType row = new RealType("row", null, null);
RealType column = new RealType("column", null, null);
RealType level = new RealType("level", null, null);
// construct RealTupleType for grid coordinates
RealType[] types3d = {row, column, level};
RealTupleType domain = new RealTupleType(types3d);
// construct RealType components for grid fields
RealType temperature = new RealType("temperature", null, null);
RealType pressure = new RealType("pressure", null, null);
RealType water_vapor = new RealType("water_vapor", null, null);
// construct RealTupleType for grid fields
RealType[] field3d = {temperature, pressure, water_vapor};
RealTupleType range = new RealTupleType(field3d);
// construct FunctionType for grid
FunctionType grid_type = new FunctionType(domain, range);
// construct RealType and RealTupleType for time domain
RealType time = new RealType("time", null, null);
RealTupleType time_type = new RealTupleType(time);
// construct FunctionType for time sequence of grids
FunctionType vis5d_type = new FunctionType(time_type, grid_type);
(time -> ((row, column, level) -> (field1, field2, ..., fieldN)))That is, they are time sequences of multivariate 3-D grids. Here's a sample of MathType analysis code (this is roughly the inverse of the code in Section 3.1.14):
// get the MathType of a Data object named 'vis5d'
FunctionType vis5d_type = (FunctionType) vis5d.getType();
// extract time, the domain of the FunctionType
RealType time = (RealType) vis5d_type.getDomain().getComponent(0);
// get grid_type, itself a FunctionType and the range of the
// vis5d_type FunctionType
FunctionType grid_type = (FunctionType) vis5d_type.getRange();
// get the grid domain RealTupleType
RealTupleType domain = grid_type.getDomain();
// get the grid domain component RealType - they are grid coordinates
RealType row = (RealType) domain.getComponent(0);
RealType column = (RealType) domain.getComponent(1);
RealType level = (RealType) domain.getComponent(2);
// get the grid range - it is a RealTupleType of fields
RealTupleType range = (RealTupleType) grid_type.getRange();
// get the number of grid range components
int dim = range.getDimension();
// construct an array to hold the grid range RealTypes
RealType[] range_types = new RealType[dim];
// get the grid range RealTypes
for (int i=0; i<dim; i++) {
range_types[i] = (RealType) range.getComponent(i);
}
Data
Scalar
Real
Text
Tuple
RealTuple
Set
(there is a large hierarchy under Set as described in Section 3.5)
Function
Field
FlatField
To some extent the Data hierarchy mirrors the MathType hierarchy. However,
it is important to note that MathType is not a synonym for Data class, since
Data classes may be elaborated into different forms of finite representation of
the corresponding MathTypes. For example, Set is elaborated into a large number
of different ways of representing subsets of R^n. Similarly, Function is
elaborated into Field, for functions represented by finite samplings, and
FlatField, for Fields with simple range values that can be represented by small
numbers of Java's primitive data types rather than by objects. Developers may
extend the Data classes to define new forms of representation. For example, a
developer could extend Real to define a representation by ratios of infinite-
precision integers rather than the Java primitive double used by Real (doubles
are used by Real because experience has shown that using floats as the default
can cause round-off problems that are extremely difficult for application
developers to detect and diagnose).The Data hierarchy is also elaborated for various data storage locations and formats. Section 6 describes how the hierarchy for Data and other VisAD classes is structured for local and remote objects, and Section 7 describes how the Data class hierarchy is adapted to import data from various file formats. The Data hierarchy is being adapted to netCDF, HDF and FITS files, and developers may extend this to other file formats. Thus data are accessible via the VisAD Data API (Application Programming Interface) independent of storage location, file format and approximating representation.
The metadata classes described in Sections 3.1 and 3.3 - 3.8 define how Data objects approximate mathematical objects and how they model the world.
Data is an interface that may apply to both local and remote Data objects. DataImpl is an abstract class that only applies to local Data objects, and RemoteData is an interface that only applies to remote Data objects (see Section 6 for more information). DataImpl is cloneable and serializable. All of its subclasses except FieldImpl and FlatField are immutable. API documentation for the Set class hierarchy is described in Section 3.5 and for FlatFields is described in Section 3.9, rather than here.
/** unit and error may be null */
public Real(RealType type, double value, Unit unit,
ErrorEstimate error) throws VisADException;
/** use RealType.Generic */
public Real(double value)
public Text(TextType type, String value) throws VisADException; /** use TextType.Generic */ public Text(String value)
/** this constructs its MathType from the MathTypes of the
data array; components are copies of data */
public Tuple(Data[] data) throws VisADException, RemoteException;
/** only copy data if copy == true */
public Tuple(Data[] data, boolean copy)
throws VisADException, RemoteException;
/** coordinate_system may be null; otherwise
coordinate_system.getReference() must equal
type.getCoordinateSystem.getReference() */
public RealTuple(RealTupleType type, Real[] reals,
CoordinateSystem coordinate_system)
throws VisADException, RemoteException;
public RealTuple(Real[] reals) throws VisADException, RemoteException;
/** FieldImpl is the most general sampled function;
domain_set defines the domain sampling;
if it is null, use the default Set of type.getDomain();
domain_set defines the Units and CoordinateSystem
of the Field domain */
public FieldImpl(FunctionType type, Set domain_set)
throws VisADException;
/** use the default Set of type.getDomain() */
public FieldImpl(FunctionType type) throws VisADException;
/** construct a RemoteFieldImpl object to provide remote
access to field */
public RemoteFieldImpl(FieldImpl field)
throws VisADException, RemoteException;
The binary and unary methods define basic mathematical operations on Data that are the building blocks for data analysis using VisAD. The binary and unary methods have wrapper methods for specific operations like add and sin. These operations are defined point-by-point for Tuple and Function Data objects, so that for example, the sin of a Function is a Function whose values are the sines of the original Function's values.
When add (or any other binary operation) is applied to two Fields the result is a Field whose values are the sums (or other operation) of the values of the two Functions, but only if the MathTypes of the two Fields match. MathType matching is defined recursively on TupleTypes and FunctionTypes in terms of their components, any RealType matches any RealType, and any TextType matches any TextType (thus matching Functions must have domains with the same dimension).
Most important, binary and unary operations on Data objects involve their metadata. When two Fields are added, the domain samples of one are resampled to the domain samples of the other, including any necessary Unit conversions of Real components of the domains and any necessary CoordinateSystem transformations between RealTuple domains. The range values of one Field are estimated at the domain sample locations of the other Field using either nearest neighbor or weighted average algorithms, as specified in the optional resampling_mode argument to binary methods. Unit conversions and CoordinateSystem transformations are also applied as needed to range values of Fields before they are added. Furthermore, ErrorEstimates attached to Field range values are modified to reflect error effects of binary and unary operations. ErrorEstimate propagation may assume either that operand errors are independently or dependently distributed, or ErrorEstimate propagation may be disabled, using the error_mode argument to binary and unary methods.
In some cases Data objects may be combined in binary operations even if their MathTypes do not match. For example, a Real object may be combined with any other Data object, and a Functions may be combined with Data objects that match the MathType of the Function's range.
public MathType getType()
throws VisADException, RemoteException;
/** flag indicating whether Data object has missing value */
public boolean isMissing()
throws VisADException, RemoteException;
/** if remote, return a local copy;
if local, return this */
public DataImpl local()
throws VisADException, RemoteException;
/** general binary operation between this and data; operation may
be Data.ADD, Data.SUBTRACT, etc; these include all binary
operations defined for Java primitive data types; new_type
is the MathType of the result; sampling_mode may be
Data.NEAREST_NEIGHBOR or Data.WEIGHTED_AVERAGE; error_mode
may be Data.INDEPENDENT, Data.DEPENDENT or Data.NO_ERRORS */
public Data binary(Data data, int operation, MathType new_type,
int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** like previous signature of binary, except the result takes
the MathType of this unless the default Units of that MathType
conflict with Units of the result, in which case a generic
MathType with appropriate Units is constructed */
public Data binary(Data data, int operation, int sampling_mode,
int error_mode)
throws VisADException, RemoteException;
public Data add(Data data, int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** use Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data add(Data data) throws VisADException, RemoteException;
public Data subtract(Data data, int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** use Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data subtract(Data data) throws VisADException, RemoteException;
/** similar methods are defined for the following binary operators:
multiply, divide, pow, max, min, atan2, atan2Degrees and
remainder */
/** general unary operation; operation may be Data.ABS, Data.ACOS, etc;
these include all unary operations defined for Java primitive data
types; new_type is the MathType of the result; sampling_mode may be
Data.NEAREST_NEIGHBOR or Data.WEIGHTED_AVERAGE; error_mode may be
Data.INDEPENDENT, Data.DEPENDENT or Data.NO_ERRORS */
public Data unary(int operation, MathType new_type, int sampling_mode,
int error_mode)
throws VisADException, RemoteException;
/** like previous signature of unary, except the result takes
the MathType of this unless the default Units of that MathType
conflict with Units of the result, in which case a generic
MathType with appropriate Units is constructed */
public Data unary(int operation, int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** clone this Data object except give it new_type */
public Data changeMathType(MathType new_type)
throws VisADException, RemoteException;
public Data abs(int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** use Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data abs() throws VisADException, RemoteException;
public Data acos(int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** use Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data acos() throws VisADException, RemoteException;
/** similar methods are defined for the following unary operators:
acosDegrees, asin, asinDegrees, atan, atanDegrees, ceil, cos,
cosDegrees, exp, floor, log, rint, round, sin, sinDegrees,
sqrt, tan, tanDegrees, negate */
public final double getValue(); /** get double value converted to unit */ public final double getValue(Unit unit) throws VisADException; public Unit getUnit(); public ErrorEstimate getError();
public String getValue();
/** return number of components */
public int getDimension();
/** return component for index between 0 and getDimension() - 1 */
public MathType getComponent(int index) throws VisADException;
/** construct Tuple; used for constructing Tuples in Spreadsheet;
e.g., link(visad.Tuple.makeTuple(A2, B1, B2)) */
public static Tuple makeTuple(Data[] datums)
throws VisADException, RemoteException
/** get Units of Real components */ public Unit[] getTupleUnits(); /** get ErrorEstimates of Real components */ public ErrorEstimate[] getErrors() throws VisADException; /** get CoordinateSystem */ public CoordinateSystem getCoordinateSystem();
/** get dimension of Function domain */
public int getDomainDimension()
throws VisADException, RemoteException;
/** get Units of domain Real components */
public Unit[] getDomainUnits()
throws VisADException, RemoteException;
/** get domain CoordinateSystem */
public CoordinateSystem getDomainCoordinateSystem()
throws VisADException, RemoteException;
/** evaluate Function at domain_value, for 1-D domains */
public Data evaluate(Real domain_value, int sampling_mode,
int error_mode)
throws VisADException, RemoteException;
/** evaluate Function at domain_value, for 1-D domains,
using Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data evaluate(Real domain_value)
throws VisADException, RemoteException;
/** evaluate Function at domain_value */
public Data evaluate(RealTuple domain_value, int sampling_mode,
int error_mode)
throws VisADException, RemoteException;
/** evaluate Function at domain_value using
Data.NEAREST_NEIGHBOR and Data.NO_ERRORS */
public Data evaluate(RealTuple domain_value)
throws VisADException, RemoteException;
/** return a Field of Function values at samples in set;
this combines unit conversions, coordinate transforms,
resampling and interpolation */
public Field resample(Set set, int sampling_mode, int error_mode)
throws VisADException, RemoteException;
/** return the derivative of this Function with respect to d_partial;
d_partial may occur in this Function's domain RealTupleType, or,
if the domain has a CoordinateSystem, in its Reference
RealTupleType; propogate errors according to error_mode */
public abstract Function derivative(RealType d_partial,
int error_mode) throws VisADException, RemoteException;
/** return the derivative of this Function with respect to d_partial;
set result MathType to derivType; d_partial may occur in this
Function's domain RealTupleType, or, if the domain has a
CoordinateSystem, in its Reference RealTupleType;
propogate errors according to error_mode */
public abstract Function derivative(RealType d_partial,
MathType derivType, int error_mode)
throws VisADException, RemoteException;
/** return the tuple of derivatives of this Function with respect to
all RealType components of its domain RealTupleType;
propogate errors according to error_mode */
public abstract Data derivative(int error_mode)
throws VisADException, RemoteException;
/** return the tuple of derivatives of this Function with respect
to all RealType components of its domain RealTupleType;
set result MathTypes of tuple components to derivType_s;
propogate errors according to error_mode */
public abstract Data derivative(MathType[] derivType_s,
int error_mode) throws VisADException, RemoteException;
/** return the tuple of derivatives of this Function with respect
to the RealTypes in d_partial_s; the RealTypes in d_partial_s
may occur in this Function's domain RealTupleType, or, if the
domain has a CoordinateSystem, in its Reference RealTupleType;
set result MathTypes of tuple components to derivType_s;
propogate errors according to error_mode */
public abstract Data derivative(RealTuple location,
RealType[] d_partial_s, MathType[] derivType_s, int error_mode)
throws VisADException, RemoteException;
/** set the values of the Field (at the domain Set samples)
using the values in range (the length of range must
equal the length of the domain Set);
make copies of range values if copy is true */
public void setSamples(Data[] range, boolean copy)
throws VisADException, RemoteException;
/** get the domain Set */
public Set getDomainSet()
throws VisADException, RemoteException;
/** get the Units of the Real components of the domain Set */
public Unit[] getDomainUnits()
throws VisADException, RemoteException;
/** get the CoordinateSystem of the domain Set */
public CoordinateSystem getDomainCoordinateSystem()
throws VisADException, RemoteException;
/** get the Field value at the index-th sample in the
domain Set */
public Data getSample(int index)
throws VisADException, RemoteException;
/** get the 'Flat' components of this Field's range values
in their default range Units (as defined by the range of
the Field's FunctionType); if the range type is a RealType
it is a 'Flat' component, if the range type is a TupleType
its RealType components and RealType components of its
RealTupleType components are all 'Flat' components; the
return array is dimensioned:
double[number_of_flat_components][number_of_range_samples] */
public double[][] getValues()
throws VisADException, RemoteException;
/** set Field value at the index-th sample in the
domain Set, to range */
public void setSample(int index, Data range)
throws VisADException, RemoteException;
/** set Field value at the sample in the domain Set nearest
domain, to range */
public void setSample(RealTuple domain, Data range)
throws VisADException, RemoteException;
/** return an Enumeration of RealTuple values in domain Set */
public Enumeration domainEnumeration()
throws VisADException, RemoteException;
/** return true is this is a FlatField */
public boolean isFlatField();
/** assumes the range type of this is a Tuple and returns
a Field with the same domain as this, but whose range
samples consist of the specified Tuple component of the
range samples of this; in shorthand, this[].component */
public Field extract(int component)
throws VisADException, RemoteException;
/** combine domains of two outpost nested Fields into a single
domain and Field; for examples transform the MathType
(a -> ((b, c) -> d)) into ((a, b, c) -> d) */
public Field domainMultiply()
throws VisADException, RemoteException;
/** factor Field domain into domains of two nested Fields (with
factor as outer domain); for examples transform the MathType
((a, b, c) -> d) into (a -> ((b, c) -> d)) (where factor = a) */
public Field domainFactor(RealType factor)
throws VisADException, RemoteException;
/** resample all elements of the fields array to the domain
set of fields[0], then return a Field whose range samples
are Tuples merging the corresponding range samples from
each element of fields; if the range of fields[i] is a
Tuple without a RangeCoordinateSystem, then each Tuple
component of a range sample of fields[i] becomes a
Tuple component of a range sample of the result -
otherwise a range sample of fields[i] becomes a Tuple
component of a range sample of the result; this assumes
all elements of the fields array have the same domain
dimension */
public static Field combine(Field[] fields)
throws VisADException, RemoteException;
grid_type =
((row, column, level) -> (temperature, pressure, water_vapor))
and:
vis5d_type = (time -> grid_type)These are the types appropriate for Vis5D data sets synthesized by the example in Section 3.1.14. This example includes constructors for an Integer3DSet and an Integer1DSet, which are described in detail in Section 3.5.3.3, and a constructor for a FlatField, which is an efficient sub-class of FieldImpl described in Section 3.9. The Integer3DSet is an integer lattice of 50 by 50 by 20 points for a Vis5D grid, and the Integer1DSet is a sequence of hour values from 0 to 23. FlatField includes a version of the setSamples method that takes an array of floats, in addition to the version of setSamples inherited from FieldImpl that takes an array of Data objects. Here's a sample of code for synthesizing a FieldImpl appropriate for a Vis5D data set:
// construct an integer 3-D grid
Set grid_set = new Integer3DSet(50, 50, 20);
// construct a sequence of 24 hours
Set time_set = new Integer1DSet(24);
// construct a FieldImpl for a time sequence of grids
FieldImpl vis5d = new FieldImpl(vis5d_type, time_set);
for (int i=0; i<24; i++) {
// conbstruct a FlatField for the i-th time step
FlatField grid = new FlatField(grid_type, grid_set);
// construct an array to hold the gridded field values;
// data[0] is an array of temperatures, data[1] an array
// of pressures, and data[2] an array of water_vapors
float[][] data = new float[3][50 * 50 * 20];
// ... code to set data values ...
// set the data values into the grid
grid.setSamples(data);
// set grid as the i-th time sample of vis5d
vis5d.setSample(i, grid);
}
ampere electric current candela luminous intensity kelvin temperature kilogram mass meter length second time mole amount of substance radian angleA Unit is defined by a set of BaseUnits with associated integer exponents, plus a real coefficient and offset. For example, yard = 0.9144 x meter, fahrenheit = (1 / 1.8) x kelvin + 459.67, and joule = kilogram x meter x second^(-2). Two Units are convertible if they have the same set of BaseUnits and integer exponents, or if the exponents of one are negatives of the exponents of the other.
Units with non-zero offsets are dangerous. For example, the conversion of fahrenheit temperature differences to kelvin differences is not correct unless the offset is ignored. In order to avoid this problem, arithmetic operations implicitly convert all inputs to Units with zero offsets.
/** create a new Unit by raising this (which may not include
an offset) to power */
public Unit pow(int power) throws UnitException;
/** create a new Unit by multiplication by amount;
for example, Unit yard = meter.scale(0.9144); */
public Unit scale(double amount) throws UnitException;
/** create a new Unit by adding offset;
for example, Unit celsius = kelvin.shift(273.15); */
public Unit shift(double offset) throws UnitException;
/** create a new Unit by multiplying this (which may not
include an offset) by that */
public Unit multiply(Unit that) throws UnitException;
/** create a new Unit by dividing this (which may not
include an offset) by that */
public Unit divide(Unit that) throws UnitException;
BaseUnit SI.ampere; BaseUnit SI.candela; BaseUnit SI.kelvin; BaseUnit SI.kilogram; BaseUnit SI.meter; BaseUnit SI.second; BaseUnit SI.mole; BaseUnit SI.radian;
/** create a new BaseUnit with the given quantityName and
unitName */
public static BaseUnit addBaseUnit(String quantityName,
String unitName) throws UnitException;
/** return any baseUnit created in this JVM with the given
unitName */
public static baseUnit unitNameToUnit(String unitName)
/** return any baseUnit created in this JVM with the given
quantityName */
public static baseUnit quantityNameToUnit(String quantityName)
Unit CommonUnit.degree;
Unit CommonUnit.radian;
Unit CommonUnit.second;
/** all BaseUnits have exponent zero in dimensionless */
Unit CommonUnit.dimensionless;
/** promiscuous is compatible with any Unit; useful for constants;
not the same as null Unit, which is only compatible with
other null Units */
Unit CommonUnit.promiscuous;
The default CoordinateSystem defined by a RealTupleType can be over-ridden for RealTuple values of that type, in order to support data-dependent CoordinateSystems. For example, meteorologists use (latitude, longitude, pressure) as a CoordinateSystem with Reference (latitude, longitude, altitude), where the mathematical transformation can vary depending on the vertical distribution of pressures. A default CoordinateSystem can only be over-ridden by a CoordinateSystem with the same Reference.
Note that care should be taken to make sure that:
/** user-defined subclasses must supply reference and units */
public CoordinateSystem(RealTupleType reference, Unit[] units)
throws VisADException;
Constructors for specific CoordinateSystems included with VisAD include:
/** construct a CoordinateSystem for (latitude, longitude,
radius) relative to a 3-D Cartesian reference;
this constructor supplies units =
{CommonUnit.Degree, CommonUnit.Degree, null} to the super
constructor, in order to ensure Unit compatibility with its
use of trigonometric functions */
public SphericalCoordinateSystem(RealTupleType reference)
throws VisADException;
/** construct a CoordinateSystem for (longitude, radius)
relative to a 2-D Cartesian reference;
this constructor supplies units = {CommonUnit.Degree, null}
to the super constructor, in order to ensure Unit
compatibility with its use of trigonometric functions */
public PolarCoordinateSystem(RealTupleType reference)
throws VisADException;
/** construct a CoordinateSystem that whose transforms invert
the transforms of inverse (i.e., toReference and
fromReference are switched); for example, this could be
used to define Cartesian coordinates relative to a
refernce in spherical coordinates */
public InverseCoordinateSystem(RealTupleType reference,
CoordinateSystem inverse)
throws VisADException;
/** construct a CoordinateSystem for grid coordinates (e.g.,
(row, column, level) in 3-D) relative to the value space
of set; for example, if satellite pixel locations are
defined by explicit latitudes and longitude, these could
be used to construct a Gridded2DSet which could then be
used to construct a GridCoordinateSystem for (ImageLine,
ImageElement) coordinates relative to reference coordinates
(Latitude, Longitude) */
public GridCoordinateSystem(GriddedSet set)
throws VisADException;
/** convert RealTuple values to Reference coordinates;
for efficiency, input and output values are passed as
double[][] arrays rather than RealTuple[] arrays; the
array indexes are:
double[tuple_dimension][number_of_tuples] */
public double[][] toReference(double[][] tuples)
throws VisADException;
/** convert RealTuple values from Reference coordinates */
public double[][] fromReference(double[][] tuples)
throws VisADException;
The following methods are implemented in CoordinateSystem in terms of the
above methods, but for efficiency's sake extensions of CoordinateSystem may
override those with direct implementations:
public float[][] toReference(float[][] tuples)
throws VisADException;
public float[][] fromReference(float[][] tuples)
throws VisADException;
Set
SimpleSet
DoubleSet
FloatSet
SampledSet
ProductSet
UnionSet
GriddedSet
LinearNDSet
IntegerNDSet
Gridded1DSet
Linear1DSet
Integer1DSet
Gridded1DDoubleSet
Gridded2DSet
Linear2DSet
LinearLatLonSet
Integer2DSet
Gridded2DDoubleSet
Gridded3DSet
Linear3DSet
Integer3DSet
Gridded3DDoubleSet
IrregularSet
Irregular1DSet
Irregular2DSet
Irregular3DSet
A SimpleSet is embedded on a sub-manifold of dimension m in R^n (m is called
the manifold dimension of the Set). A DoubleSet with domain dimension n is just
the large but finite set of values in R^n representable by n IEEE double
precision floating point values. Similarly for FloatSet and single precision.
The SampledSet class implements some common methods for its subclasses. The
samples of a GriddedSet are organized in an m-dimensional grid. For a LinearSet
this grid is aligned to the axes of the domain R^n and for an IntegerSet the
grid points form an integer lattice based at the origin. The samples of an
IrregularSet are not organized. ProductSets and UnionSets allow Sets to be
defined as products and unions of other Sets.Note that Set is a sub-class of Data, so Sets are full-fledged Data objects in addition to being a form of metadata for Fields. For example, a set of map boundaries would be a Set with domain dimension n = 2 and manifold dimension m = 1.
Note also that there is a Set class in the java.util package as of JDK 1.2. Thus applications should avoid combining:
import visad.*;with:
import java.util.*;
Implementation of interpolation methods not consistent with weighted average would require extensions of Field and FlatField. Nearest neighbor resampling uses the valueToIndex method of Set.
The getWedge method of SimpleSet is important for the efficiency of Field resampling and interpolation. The samples of one Set are passed to the valueToInterp and valueToIndex of another set in an order defined the first Set's getWedge method. Sets use getWedge to define a spatially coherent order of their samples. It is important that developers who extend SimpleSet try to define spatially coherent orders in their implementations of getWedge.
Note that valueToInterp and valueToIndex generally throw an Exception for any Set whose manifold dimension is less than its domain dimension. Thus the resample method does not work for Fields whose domain Sets have manifold dimension less than their domain dimension. In order to resample a Field X over a domain of dimension N with manifold dimension M < N, applications must explicitly copy values of X to another Field Y whose domain has dimension M and is a parameterization of the sub-manifold containing the samples of X. For example, if N = 3 and M = 2, then the samples of X lie on a 2-D surface embedded in a 3-D space, and the domain of Y should be a parameterization of this surface, with samples locations corresponding to X's sample locations on the surface.
Delaunay
DelaunayClarkson
DelaunayWatson
DelaunayFast
DelaunayCustom
The DelaunayClarkson class computes Delaunay triangulations in any dimension
between 2 and 8 using Ken Clarkson's algorithm. DelaunayCustom constructors
accept sampling topologies from applications. The DelaunayWatson class computes
Delaunay triangulations in 2 or 3 dimensions using David Watson's algorithm.
The DelaunayFast class computes non-Delaunay triangulations quickly.Note that any computation of Delaunay or approximate Delaunay topology is extremely slow and apt to exceed available memory for large Sets. Hence, where an irregular topology is known to the application, we strongly recommend that the topology be supplied by the application through the DelaunayCustom constructor.
/** the set of values representable by N doubles;
type must be a RealType, a RealTupleType or a SetType;
coordinate_system and units must be compatible with defaults
for type, or may be null;
a DoubleSet may not be used as a Field domain */
public DoubleSet(MathType type, CoordinateSystem coordinate_system,
Unit[] units) throws VisADException;
/** the set of values representable by N floats;
type must be a RealType, a RealTupleType or a SetType;
coordinate_system and units must be compatible with defaults
for type, or may be null;
a FloatSet may not be used as a Field domain */
public FloatSet(MathType type, CoordinateSystem coordinate_system,
Unit[] units) throws VisADException;
Linear1DSet, Linear2DSet, Linear3DSet are redundant with LinearNDSet but have more efficient implementations.
The samples of a LinearSet are in raster order, with component values for the first dimension changing fastest and component values for the last dimension changing slowest (this is the same as the ordering of elements in a multi- dimensional Fortran array). For example, given a Linear2DSet with domain type (X, Y) that is a product of six X samples and five Y samples, the 2-D samples are ordered as:
Y (second) component
X 0 6 12 18 24
1 7 13 19 25
(first) 2 8 14 20 26
3 9 15 21 27
component 4 10 16 22 28
5 11 17 23 29
LinearSets extend GriddedSets, described in Section 3.5.3.3. GriddedSets
have rectangular topology while LinearSets have rectangular topology and
geometry.
/** an arithmetic progression of length values between first and last;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Linear1DSet(MathType type,
double first, double last, int length,
CoordinateSystem coordinate_system, Unit[] units,
ErrorEstimate[] errors) throws VisADException;
/** a 1-D arithmetic progression with null errors and generic type */
public Linear1DSet(double first, double last, int length)
throws VisADException;
/** a 2-D cross product of arithmetic progressions;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Linear2DSet(MathType type,
double first1, double last1, int length1,
double first2, double last2, int length2,
CoordinateSystem coordinate_system, Unit[] units,
ErrorEstimate[] errors) throws VisADException;
/** a 2-D cross product of arithmetic progressions with
null errors and generic type */
public Linear2DSet(double first1, double last1, int length1,
double first2, double last2, int length2)
throws VisADException;
/** a 3-D cross product of arithmetic progressions;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Linear3DSet(MathType type,
double first1, double last1, int length1,
double first2, double last2, int length2,
double first3, double last3, int length3,
CoordinateSystem coordinate_system, Unit[] units,
ErrorEstimate[] errors) throws VisADException;
/** a 3-D cross product of arithmetic progressions with
null errors and generic type */
public Linear3DSet(double first1, double last1, int length1,
double first2, double last2, int length2,
double first3, double last3, int length3)
throws VisADException;
/** a 2-D cross product of arithmetic progressions that whose east
and west edges may be joined (for interpolation purposes);
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public LinearLatLonSet(MathType type,
double first1, double last1, int length1,
double first2, double last2, int length2,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 2-D cross product of arithmetic progressions that whose east
and west edges may be joined (for interpolation purposes), with
null errors, CoordinateSystem and Units are defaults from type */
public LinearLatLonSet(MathType type,
double first1, double last1, int length1,
double first2, double last2, int length2)
throws VisADException;
/** construct an N-dimensional set as the product of N Linear1DSets;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public LinearNDSet(MathType type, Linear1DSet[] sets,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** construct an N-dimensional set as the product of N Linear1DSets,
with null errors, CoordinateSystem and Units are defaults from
type */
public LinearNDSet(MathType type, Linear1DSet[] sets)
throws VisADException;
/** construct an N-dimensional set as the product of N arithmetic
progressions; coordinate_system and units must be compatible
with defaults for type, or may be null; errors may be null */
public LinearNDSet(MathType type, double[] firsts, double[] lasts,
int[] lengths, CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** construct an N-dimensional set as the product of N arithmetic
progressions, with null errors, CoordinateSystem and Units are
defaults from type */
public LinearNDSet(MathType type, double[] firsts, double[] lasts,
int[] lengths) throws VisADException;
IntegerSets are useful as the domains of Fields that are really just simple 1-D, 2-D, 3-D or N-D arrays of values.
/** construct a 1-dimensional set with values {0, 1, ..., lengthX-1};
coordinate_system and units must be compatible with defaults for
type, or may be null; errors may be null */
public Integer1DSet(MathType type, int lengthX,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 1-D set with null errors and generic type */
public Integer1DSet(int lengthX)
throws VisADException;
/** construct a 2-dimensional set with values
{0, 1, ..., lengthX-1} x {0, 1, ..., lengthY-1};
coordinate_system and units must be compatible with defaults for
type, or may be null; errors may be null */
public Integer2DSet(MathType type, int lengthX, lengthY,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 2-D set with null errors and generic type */
public Integer2DSet(int lengthX, lengthY)
throws VisADException;
/** construct a 3-dimensional set with values {0, 1, ..., lengthX-1}
x {0, 1, ..., lengthY-1} x {0, 1, ..., lengthZ-1};
coordinate_system and units must be compatible with defaults for
type, or may be null; errors may be null */
public Integer3DSet(MathType type, int lengthX, lengthY, lengthZ,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 3-D set with null errors and generic type */
public Integer3DSet(int lengthX, lengthY, lengthZ)
throws VisADException;
/** construct an N-dimensional set with values in the cross product
of {0, 1, ..., lengths[i]-1}
for i=0, ..., lengths[lengths.length-1];
coordinate_system and units must be compatible with defaults for
type, or may be null; errors may be null */
public IntegerNDSet(MathType type, int[] lengths,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** an N-D set with null errors and generic type */
public IntegerNDSet(int[] lengths)
throws VisADException;
GriddedSets may have manifold dimension less than (or equal to) their domain dimension. A GriddedSet with domain dimension N and manifold dimension M defines an M-dimensional grid of samples embedded in an N-dimensional space. In the GriddedSet constructors, the arguments lengthX, lengthY and lengthZ define the numbers of samples along each dimension of the grid (so the number of length arguments defines the manifold dimension), and the samples array argument defines the locations of grid points in N-dimensional domain space. The samples array has type float[][] with dimensions float[N][number_of_samples]. Thus the i-th point in the grid is located at:
(samples[0][i], samples[1][i], ..., samples[N-1][i]).The samples are in raster order, with the first grid dimension changing fastest and the last grid dimension changing slowest. That is, the first lengthX samples form the first 'column' of the grid, the first (lengthX * lengthY) samples for the first sub-plane of the grid, and so on.
If the manifold dimension is less than the domain dimension or any of the grid sizes (i.e., lengthX, lengthY or lengthZ) is 1, then the valueToIndex and valueToInterp methods will throw an Exception. If the manifold dimension equals the domain dimension and all of the grid sizes is greater than 1, then the GriddedSet constructor will perform numerical checks on the samples array to ensure that form a valid grid (e.g., to ensure that they are sorted in the 1-D case).
/** a 1-D sorted sequence with no regular interval; samples array
is organized float[1][number_of_samples] where lengthX =
number_of_samples; samples must be sorted (either increasing
or decreasing); coordinate_system and units must be compatible
with defaults for type, or may be null; errors may be null */
public Gridded1DSet(MathType type, float[][] samples, int lengthX,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 1-D sequence with no regular interval with null errors,
CoordinateSystem and Units are defaults from type */
public Gridded1DSet(MathType type, float[][] samples, int lengthX)
throws VisADException;
/** a 1-D sorted sequence with no regular interval; samples array
is organized double[1][number_of_samples] where lengthX =
number_of_samples; samples must be sorted (either increasing
or decreasing); coordinate_system and units must be compatible
with defaults for type, or may be null; errors may be null */
Gridded1DDoubleSet is useful for sequences of DataTime values
represented as double precision seconds */
public Gridded1DDoubleSet(MathType type, double[][] samples,
int lengthX, CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 1-D sequence with no regular interval with null errors,
CoordinateSystem and Units are defaults from type;
Gridded1DDoubleSet is useful for sequences of DataTime values
represented as double precision seconds */
public Gridded1DDoubleSet(MathType type, double[][] samples,
int lengthX)
throws VisADException;
/** a 2-D set whose topology is a lengthX x lengthY grid;
samples array is organized float[2][number_of_samples] where
lengthX * lengthY = number_of_samples; samples must form a
non-degenerate 2-D grid (no bow-tie-shaped grid boxes); the
X component increases fastest in the second index of samples;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Gridded2DSet(MathType type, float[][] samples, int lengthX,
int lengthY, CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 2-D set whose topology is a lengthX x lengthY grid, with
null errors, CoordinateSystem and Units are defaults from type */
public Gridded2DSet(MathType type, float[][] samples, int lengthX,
int lengthY) throws VisADException;
/** a 2-D set with manifold dimension = 1; samples array is
organized float[2][number_of_samples] where lengthX =
number_of_samples; no geometric constraint on samples;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Gridded2DSet(MathType type, float[][] samples, int lengthX,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 2-D set with manifold dimension = 1, with null errors,
CoordinateSystem and Units are defaults from type */
public Gridded2DSet(MathType type, float[][] samples, int lengthX)
throws VisADException;
/** a 3-D set whose topology is a lengthX x lengthY x lengthZ
grid; samples array is organized float[3][number_of_samples]
where lengthX * lengthY * lengthZ = number_of_samples;
samples must form a non-degenerate 3-D grid (no bow-tie-shaped
grid cubes); the X component increases fastest and the Z
component slowest in the second index of samples;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Gridded3DSet(MathType type, float[][] samples, int lengthX,
int lengthY, int lengthZ,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 3-D set whose topology is a lengthX x lengthY x lengthZ
grid, with null errors, CoordinateSystem and Units are
defaults from type */
public Gridded3DSet(MathType type, float[][] samples, int lengthX,
int lengthY, int lengthZ) throws VisADException;
/** a 3-D set with manifold dimension = 2; samples array is
organized float[3][number_of_samples] where lengthX * lengthY
= number_of_samples; no geometric constraint on samples; the
X component increases fastest in the second index of samples;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Gridded3DSet(MathType type, float[][] samples, int lengthX,
int lengthY, CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 3-D set with manifold dimension = 2, with null errors,
CoordinateSystem and Units are defaults from type */
public Gridded3DSet(MathType type, float[][] samples, int lengthX,
int lengthY) throws VisADException;
/** a 3-D set with manifold dimension = 1; samples array is
organized float[3][number_of_samples] where lengthX =
number_of_samples; no geometric constraint on samples;
coordinate_system and units must be compatible with defaults
for type, or may be null; errors may be null */
public Gridded3DSet(MathType type, float[][] samples, int lengthX,
CoordinateSystem coordinate_system, Unit[] units,
ErrorEstimate[] errors)
throws VisADException;
/** a 3-D set with manifold dimension = 1, with null errors,
CoordinateSystem and Units are defaults from type */
public Gridded3DSet(MathType type, float[][] samples, int lengthX)
throws VisADException;
The samples array argument to the IrregularSet constructors defines the locations of sample points in N-dimensional domain space. The samples array has type float[][] with dimensions float[N][number_of_samples]. Thus the i-th sample point is located at:
(samples[0][i], samples[1][i], ..., samples[N-1][i]).IrregularSets may have manifold dimension less than or equal to their domain dimension. If the manifold dimension is less than the domain dimension, then the valueToIndex and valueToInterp methods throw Exceptions.
In 1 dimension the topology is constructed merely by sorting the samples. In higher dimensions the topology may be constructed by a Delaunay triangulation or may be specified in the constructor (using the DelaunayCustom class). See Section 3.5.5 for more information about Delaunay classes.
/** a 1-D irregular set; samples array is organized
float[1][number_of_samples]; samples need not be
sorted - the constructor sorts samples to define
a 1-D "triangulation";
coordinate_system and units must be compatible with
defaults for type, or may be null; errors may be null */
public Irregular1DSet(MathType type, float[][] samples,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** a 1-D irregular set with null errors, CoordinateSystem
and Units are defaults from type */
public Irregular1DSet(MathType type, float[][] samples)
throws VisADException;
/** a 2-D irregular set; samples array is organized
float[2][number_of_samples]; no geometric constraint on
samples; if delan is non-null it defines the topology of
samples (which must have manifold dimension 2), else the
constructor computes a topology with manifold dimension 2;
note that Gridded2DSet can be used for an irregular set
with domain dimension 2 and manifold dimension 1;
coordinate_system and units must be compatible with
defaults for type, or may be null; errors may be null */
public Irregular2DSet(MathType type, float[][] samples,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors,
Delaunay delan)
throws VisADException;
/** a 2-D irregular set with null errors, CoordinateSystem
and Units are defaults from type; topology is computed
by the constructor */
public Irregular2DSet(MathType type, float[][] samples)
throws VisADException;
/** a 3-D irregular set; samples array is organized
float[3][number_of_samples]; no geometric constraint on
samples; if delan is non-null it defines the topology of
samples (which may have manifold dimension 2 or 3), else
the constructor computes a topology with manifold dimension
3; note that Gridded3DSet can be used for an irregular set
with domain dimension 3 and manifold dimension 1;
coordinate_system and units must be compatible with
defaults for type, or may be null; errors may be null */
public Irregular3DSet(MathType type, float[][] samples,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors,
Delaunay delan)
throws VisADException;
/** a 3-D irregular set with null errors, CoordinateSystem
and Units are defaults from type; topology is computed
by the constructor */
public Irregular3DSet(MathType type, float[][] samples)
throws VisADException;
UnionSets are SampledSets that are defined as unions of other SampledSets. All the sets in the union must have the same domain dimension and they must all have the same manifold dimension. Note that the valueToInterp method is not implemented for UnionSets but the valueToIndex method is. Thus if a UnionSet is the domain set of a Field, arithmetic operations involving the Field must specify the Data.NEAREST_NEIGHBOR resampling mode rather than Data.WEIGHTED_AVERAGE. The order of samples in a UnionSet is the serialization of the orders of samples of its components. As the index of the UnionSet increases, the samples of the first component are enumerated first and the samples of the last component are enumerated last.
/** create the product of the sets array; coordinate_system
and units must be compatible with defaults for type,
or may be null; errors may be null */
public ProductSet(MathType type, SampledSet[] sets,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** create the product of the sets array, with null errors,
CoordinateSystem and Units are defaults from type */
public ProductSet(MathType type, SampledSet[] sets)
throws VisADException;
/** create the union of the sets array; coordinate_system
and units must be compatible with defaults for type,
or may be null; errors may be null */
public UnionSet(MathType type, SampledSet[] sets,
CoordinateSystem coordinate_system,
Unit[] units, ErrorEstimate[] errors)
throws VisADException;
/** create the union of the sets array, with null errors,
CoordinateSystem and Units are defaults from type */
public UnionSet(MathType type, SampledSet[] sets)
throws VisADException;
/** return an enumeration of sample indices in a spatially
coherent order; this is useful for efficiency */
public int[] getWedge();
/** return an enumeration of sample values in index order
(i.e., not in getWedge order); the return array is
organized as float[domain_dimension][number_of_samples] */
public float[][] getSamples() throws VisADException;
/** convert an array of indices to an array of sample values;
the return array is organized as
float[domain_dimension][indices.length] */
public float[][] indexToValue(int[] indices) throws VisADException;
/** convert an array of values to an array of indices of the nearest
samples; the values array is organized as
float[domain_dimension][number_of_values] */
public int[] valueToIndex(float[][] values) throws VisADException;
/** convert an array of indices to an array of double precision
sample values; this precision is currently only meaningful
for Linear1DSet and Gridded1DDoubleSet where it is intended
to represent date/time values as double precision seconds;
the return array is organized as
double[domain_dimension][indices.length] */
public double[][] indexToDouble(int[] indices) throws VisADException;
/** convert an array of double precision values to an array of
indices of the nearest samples; this precision is currently
only meaningfulful for Linear1DSet and Gridded1DDoubleSet
where it is intended to represent date/time values as double
precision seconds; the values array is organized as
double[domain_dimension][number_of_values] */
public int[] doubleToIndex(double[][] values) throws VisADException;
/** convert an array of values to arrays of indices and weights for
those indices, appropriate for interpolation; the values array is
organized as float[domain_dimension][number_of_values]; indices
and weights must be passed in as int[number_of_values][] and
float[number_of_values][]; on return, quantity( values[.][i] )
can be estimated as the sum over j of
weights[i][j] * quantity (sample at indices[i][j]);
no estimate possible if indices[i] and weights[i] are null */
public void valueToInterp(float[][] values, int[][] indices,
float[][] weights) throws VisADException;
/** the DelaunayCustom constructor allows applications to define
sampling topologies; the samples array is organized as
float[domain_dimension][number_of_samples] and the tris arrays
is organized as int[number_of_tris][manifold_dimension + 1];
each "tri" is a list of sample indices, and is a triangle,
tetrahedron, etc depending on manifold dimension */
public DelaunayCustom(float[][] samples, int[][] tris)
throws VisADException;
Data operations include options to propagate ErrorEstimates assuming that errors are distributed either independently or dependently, as well as an option to not propagate ErrorEstimates.
The VisAD ErrorEstimates are not a substitute for a detailed error analysis, but can provide a quick estimate of error magnitude and the possible need for detailed analysis.
/** construct an error distribution of number values with
given mean and variance, in Unit unit */
public ErrorEstimate(double variance, double mean,
long number, Unit unit);
/** construct an error distribution of 1 value with
given mean and variance, in Unit unit */
public ErrorEstimate(double mean, double variance, Unit unit);
The AuditTrail class is not yet implemented, so there is no constructor and method documentation.
* Apply all data operations to arrays of values rather than individual values,
and avoid methods that are invoked once per data value.
The effectiveness of this rule was demonstrated in the C implementation of VisAD
[8, 9], which had a general data model like the Java implementation.The large Data objects in any application are Fields. Most array data in numerical programs are finite samplings of functions (for example, images are finite samplings of continuous radiance functions with a pixel for each sample) and these correspond to Fields. Even arrays that do not correspond to any obvious continuous function can be represented by Fields whose domains are sets of integers from 1 to N. The obvious way to implement the Field class is with an array of range sample objects, which would violate our rule because Field operations invoke methods on each range object. Thus the Field class is extended by FlatField, which simulates an array of range objects with arrays of Java primitive values. A FlatField can be used for a Field under the following two conditions:
In addition to computational efficiency, FlatFields also have better storage efficiency than Fields. Java primitive data require less storage than Java objects, shared metadata objects require less total space, and when possible function range values are stored in bytes, shorts or ints rather than floats. The FlatField constructor accepts range sampling Sets for each RealType component of its range. If the size of the sampling Set for a range component is 255, then values for that component are encoded as indices into that Set and stored in an array of bytes (the 256th code is used to represent missing values). Arrays of shorts or ints are used for larger set sizes, as appropriate. The default range sampling Sets are 1-D FloatSets, which cause range values to be stored as floats.
Numerical precision problems occur and can be very difficult to diagnose when they do. Thus developers may want to pass DoubleSets to the range sampling Sets argument of the FlatField constructor, in order to avoid precision problems.
Float.NaN and Double.NaN are used to represent missing float and double values. This avoids time-consuming explicit tests for missing values, since these IEEE NaNs have the right arithmetic semantics for missing values.
/** FlatField is a sampled function whose range is a Real,
a RealTuple, or a Tuple of Reals and RealTuples; if range
is a RealTuple, range_coordinate_system may be non-null
but must have the same Reference as RangeType default
CoordinateSystem; domain_set defines the domain sampling;
range_sets define samplings for range values - if range_set[i]
is null, the i-th range component values are stored as doubles;
if range_set[i] is non-null, the i-th range component values are
stored in bytes if range_sets[i].getLength() < 256, stored in
shorts if range_sets[i].getLength() < 65536, etc;
any argument but type may be null */
public FlatField(FunctionType type, Set domain_set,
CoordinateSystem range_coordinate_system,
Set[] range_sets, Unit[] units)
throws VisADException;
/** similar to the previous constructor, except that if
range_coordinate_systems[i] is non-null, then the i-th
component of the range type must be a RealTupleType whose
default CoordinateSystem has the same Reference */
public FlatField(FunctionType type, Set domain_set,
CoordinateSystem[] range_coordinate_systems,
Set[] range_sets, Unit[] units)
throws VisADException;
/** convert FlatField to FieldImpl */
public Field convertToField()
throws VisADException, RemoteException;
/** return array of Units associated with each RealType
component of range; these may differ from default
Units of range RealTypes, but must be convertable */
public Unit[][] getRangeUnits();
/** return range CoordinateSystem assuming range type is
a RealTupleType (throws a TypeException if its not);
this may differ from default CoordinateSystem of
range RealTupleType, but must be convertable */
public CoordinateSystem[] getRangeCoordinateSystem();
/** return range CoordinateSystem associated with
RealTupleType that is index-th component of range
TupleType; this may differ from default
CoordinateSystem of RealTupleType component of
range TupleType, but must be convertable */
public CoordinateSystem[] getRangeCoordinateSystem(int index);
/** return array of ErrorEstimates associated with each
RealType component of range; each ErrorEstimate is a
mean error for all samples of a range RealType
component */
public ErrorEstimates[] getRangeErrors();
/** set ErrorEstimates associated with each RealType
component of range */
public void setRangeErrors(ErrorEstimates[] errors)
throws VisADException;
/** set range array as range values of this FlatField;
the array is dimensioned
double[number_of_range_components][number_of_range_samples];
copy array if copy flag is true */
public void setSamples(double[][] range, boolean copy)
throws VisADException, RemoteException;
/** set range array as range values of this FlatField;
the array is dimensioned
double[number_of_range_components][number_of_range_samples];
copy array if copy flag is true */
public void setSamples(float[][] range, boolean copy)
throws VisADException, RemoteException;
/** get this FlatField's range values in their default range
Units (as defined by the range of the FlatField's
FunctionType); the return array is dimensioned
double[number_of_range_components][number_of_range_samples] */
public double[][] getValues()
throws VisADException, RemoteException;
/** construct a DataReferenceImpl object with the given name */
public DataReferenceImpl(String name) throws VisADException;
/** construct a RemoteDataReferenceImpl object to provide remote
access to reference */
public RemoteDataReferenceImpl(DataReferenceImpl reference)
throws RemoteException;
/** get MathType of referenced Data object, or null if none;
this is more efficient than getData().getType() for
RemoteDataReferences */
public MathType getType() throws VisADException, RemoteException;
/** get referenced Data object, or null if none */
public Data getData() throws VisADException, RemoteException;
/** set reference to data, replacing any currently referenced
Data object; if this is local (i.e., an instance of
DataReferenceImpl) then the data argument must also be
local (i.e., an instance of DataImpl);
if this is Remote (i.e., an instance of RemoteDataReference)
then a local data argument (i.e., an instance of DataImpl)
will be passed by copy and a remote data argument (i.e., an
instance of RemoteData) will be passed by remote reference */
public void setData(Data data) throws VisADException, RemoteException;
struct pixel {
float ir_radiance;
float vis_radiance;
};
struct pixel image[nlines][nelements];
A similar multi-spectral image can be defined in VisAD using RealTupleTypes and
a FunctionType:
RealTupleType location = new RealTupleType(new RealType("line"),
new RealType("element")),
RealTupleType pixel = new RealTupleType(new RealType("ir_radiance"),
new RealType("vis_radiance")),
FunctionType image_type = new FunctionType(location, pixel);
Set location_set = new Integer2DSet(nlines, nelements);
FlatField image = new FlatField(image_type, location_set);
In general, we can list the following analogies between C and VisAD data
structuring tools:
C VisAD
float, double, int RealType
char string[] TextType
struct TupleType, RealTupleType
array FunctionType
In these analogies, C and VisAD syntax differ considerably. However, that
kind of difference should be familiar to programmers with experience in several
programming languages. The important similarities and differences relate to the
meanings of these data structuring tools. Most differences involve metadata
integrated into the meanings of data. For example, VisAD Reals and C floats
implement the same set of operations, but operations on VisAD Reals may invoke
Unit conversions and propogate ErrorEstimates and missing data indicators (some
C implementations also propogate missing data indicators in the form of IEEE
NaNs). C structs and VisAD Tuples have very similar meanings - they are both
fixed length lists of other data structures. However, VisAD RealTuples may
include CoordinateSystems and operations on RealTuples may invoke coordinate
transforms.The most complex differences exist for the analogy between C arrays and VisAD Functions, because of the variety of metadata integrated into VisAD Functions. The rest of this section of the Developers Guide is dedicated to explaining the relation between arrays and Functions in a series of program examples. With the proper understanding, you can use Functions anywhere you can use arrays, but Functions also allow you to express some very complex operations simply.
#define nlines 256
#define nelements 256
struct pixel {
float ir_radiance;
float vis_radiance;
};
image_difference(image1, image2)
struct pixel image1[nlines][nelements];
struct pixel image2[nlines][nelements];
{
int i, j;
for (i=0; i<nlines; i++) {
for (j=0; j<nelements; j++) {
image1[i][j].ir_radiance -= image2[i][j].ir_radiance;
image1[i][j].vis_radiance -= image2[i][j].vis_radiance;
}
}
}
This code assumes a fixed size for its image arguments, but that would not
be hard to generalize. It also assumes a fixed set of spectral bands for its
image arguments, that both images have the same size, that their pixel locations
are aligned, and that image radiance values have the same units and calibration.
void image_difference(FlatField image1, FlatField image2)
throws VisADException, RemoteException {
// extract pixel radiance values from images
double[][] pixels1 = image1.getValues();
double[][] pixels2 = image2.getValues();
// loop over spectral bands in image1
for (int i=0; i<pixels1.length; i++) {
// loop over pixels in one spectral band
for(int j=0; j<pixels1[i].length; j++) {
pixels1[i][j] -= pixels2[i][j];
}
}
// set pixel radiance values in image1
image1.setSamples(pixels1);
}
This code does not assume a fixed size for its image arguments, and does not
assume that they have only two spectral bands. However, it does assume that
both images have the same size and the same set of spectral bands, that their
pixel locations are aligned, and that image radiance values have the same units
and calibration.This code example demonstrates that it is easy to treat VisAD Functions like simple arrays, extracting their values into ordinary arrays using the getValues method and setting values from ordinary arrays using the setSamples method.
FlatField image_difference(FlatField image1, FlatField image2)
throws VisADException, RemoteException {
return (FlatField) image1.subtract(image2);
}
This code only assumes that the two images have the same set of spectral
bands. If necessary it will resample the locations of image2 to the locations
of image1, transform locations from one coordinate system to another and convert
location units, convert radiance units and transform between radiance
calibration coordinate systems, and propogate error estimates and missing data
indicators.This code example demonstrates that Functions can be manipulated at a high level, similar to array operations in some high-level languages (such as IDL) but integrating a variety of metadata in those operations. High-level operations on Functions include basic arithmetic such as add and multiply with other Functions or with Reals, as well as derivative, resampling, and display.
VisAD shields applications developers from details of graphics APIs. Thus for most applications, the only difference between Java3D and Java2D displays is whether they are constructed with DisplayImplJ3D or DisplayImplJ2D, and the constraint that Java2D displays cannot involve ScalarMaps to ZAxis, Latitude or Alpha.
The following description of the VisAD display architecture is complex but ordinary applications can use it quite simply, as illustrated by the application source code examples.
(XAxis, YAxis, ZAxis) = DisplaySpatialCartesianTuple (Latitude, Longitude, Radius) = DisplaySpatialSphericalTuple (CylRadius, CylAzimuth, CylZAxis) = DisplaySpatialCylindricalTuple (Red, Green, Blue) = DisplayRGBTuple (Hue, Saturation, Brightness) = DisplayHSBTuple (Cyan, Magenta, Yellow) = DisplayCMYTuple RGB, HSV, CMY // indices into pseudo color table RGBA // index into pseudo color-alpha table Alpha // transparency Animation // index into animation sequence SelectValue, SelectRange // select Data components for display IsoContour // iso-contour lines and surfaces (Flow1X, Flow1Y, Flow1Z) = DisplayFlow1Tuple // vector rendering (Flow2X, Flow2Y, Flow2Z) = DisplayFlow2Tuple // 2nd vector set (XAxisOffset, YAxisOffset, ZAxisOffset) = DisplaySpatialOffsetTuple Shape // index into list of icon shapes ShapeScale // relative scale of icon shapes Text // TextTypes and RealTypes can be mapped to Text LineWidth, PointSize // for ConstantMap onlyDevelopers may define new DisplayRealTypes and DisplayTupleTypes to define parameters of new kinds of displays, as described in Section 4.1.1. In particular developers may define new display spatial and color coordinate systems that can be used by existing DataRenderers and DisplayRenderers.
Some DisplayRealTypes define a range of values (e.g., 0.0 to 1.0). Values for these DisplayRealTypes are derived from mapped RealType values by linear scaling. The scale and offset are computed so that the range of RealType values is mapped precisely to the range of DisplayRealType values. Application can define the range of RealType values using the setRange method of ScalarMap, otherwise they are automatically computed from the displayed Data objects.
Each DisplayRealType defines a default value (most are 0.0, but for example the default for Radius is 1.0), which is over-ridden by values of any RealTypes mapped to the DisplayRealType. ConstantMap is a sub-class of ScalarMap and defines a mapping from a constant to a DisplayRealType (for example, to over- ride the default value for Radius). Each DataReference linked to a Display may also include its own private set of ConstantMaps. This can be used, for example, to set a different color for each Data object, or to set a different ZAxis depth for each of a set of image Data objects displayed with transparent color in the XY plane.
The meanings of most DisplayRealTypes should be fairly obvious, but a few need some explanation. SelectRange and SelectValue are used to display only selected parts of Data objects, depending on whether values of RealTypes mapped to SelectRange lie in a specified range and whether values of RealTypes mapped to SelectValue have a specified value (this is only applicable to RealTypes occurring as 1-D Field domains and the value tolerance is defined according to the Field domain sampling Set). Animation is also only applicable to RealTypes occurring as 1-D Field domains and the discrete animation steps are defined from Field domain sampling Sets. The components of DisplaySpatialOffsetTuple are used to generate display spatial coordinates as the sums of values from multiple RealTypes. This could be used, for example, to define Beshers and Feiner's "worlds within worlds" display [2].
Display.Shape can be a very powerful tool for creating complex displays but is also a bit complex. See Section 4.7 for more information.
TextTypes may only be mapped to Display.Text, or left unmapped. RealTypes may also be mapped to Display.Text.
In Figure 1 (which is supplied with some hard copies of this guide, and is also available at http://www.ssec.wisc.edu/~billh/figure1.gif), the top-left panel shows a Data object with MathType:
( (nl, nchan) -> wfn )displayed according to the mappings:
nl -> YAxis wfn -> ZAxis 0.5 -> Blue nchan -> XAxis wfn -> Green 0.5 -> RedIt is possible to map data to displays via the Reference RealTupleTypes of CoordinateSystems occurring in Data objects. For example, given a Data object with MathType:
( (lon, radius) -> (vis_radiance, ir_radiance) )where (lon, radius) has a PolarCoordinateSystem with Reference (x, y), it is possible to display this Data object using the mappings:
x -> XAxis 0.5 -> Blue vis_radiance -> Green y -> YAxis 0.5 -> RedThis display can be seen with the command 'java DisplayTest 11' in the visad/examples directory.
Note that the main method of DisplayTest provides many examples of how ScalarMaps can be used.
Classes that implement the ScalarMapListener interface can be attached to ScalarMaps via their addScalarMapListener method. ScalarMaps send ScalarMapEvents to attached ScalarMapListeners when their range of values is changed by display autoscaling. ScalarMapEvents include a reference to the ScalarMap that generated them, and ScalarMaps are Serializable, so they can be used between different JVMs (i.e., different computers or different Java interpreters on the same computer).
Rather than focusing on the complex constraints described in Appendix A it is easiest to apply common sense in defining ScalarMaps.
The RealType components of FlatField domains should be mapped to XAxis, YAxis and ZAxis or to Latitude, Longitude and Radius (but note that Cartesian and spherical spatial coordinates cannot be mixed). The RealType components of FlatField ranges should be mapped to one of the color DisplayRealTypes (e.g., Green, RGB), Alpha (transparency), IsoContour, one of the flow DisplayRealTypes (e.g., Flow1X, Flow1Y), Shape (although note that Shape is not implemented in the initial release of VisAD) or to a spatial coordinate not mapped from the domain (note that multiple RealType components from the same FlatField cannot be mapped to the same spatial coordinates).
However, in order to produce scatter plots of FlatField range values (e.g., scatter plots relating the different radiance channels of a satellite image) the RealType components of the FlatField domain should generally not be mapped while the RealType components of the range (i.e., the different radiance channel types) should be mapped to spatial coordinates and to color DisplayRealTypes (for colored scatter plots).
When FunctionTypes are nested in the ranges of other FunctionTypes (for example, a time sequence of images) RealType components of the outer Field domain should be mapped to Animation, SelectValue, SelectRange, color DisplayRealTypes, and spatial offsets (e.g., XAxisOffset). However, note that only RealType components of 1-D Field domains may be mapped to Animation or SelectValue.
When Tuples include RealType components and FunctionType components, DisplayRealTypes mapped from the RealType components will affect the depiction of the FunctionType components. They should be mapped to color DisplayRealTypes, spatial offsets and SelectRange.
/** construct a DisplayRealType with given name (used only for
user interfaces), single flag (if true, this DisplayRealType
may only occur once in a path to a terminal node, as defined
in Appendix A), (low, hi) range of values, default value,
and unit */
public DisplayRealType(String name, boolean single, double low,
double hi, double default, Unit unit)
throws VisADException;
/** similar to above constructor but without value range;
values of RealTypes mapped to this DisplayRealType are
not scaled */
public DisplayRealType(String name, boolean single,
double default, Unit unit)
throws VisADException;
/** if coord_sys is not null then coord_sys.Reference
must be another DisplayTupleType; a DisplayrealType may
not be a component of more than one DisplayTupleType */
public DisplayTupleType(DisplayRealType[] types,
CoordinateSystem coord_sys)
throws VisADException;
public DisplayTupleType(DisplayRealType[] types)
throws VisADException;
/** return the unique DisplayTupleType that this
DisplayRealType is a component of, or return null
if it is not a component of any DisplayTupleType */
public DisplayTupleType getTuple();
/** return index of this as component of a
DisplayTupleType */
public getTupleIndex();
/** return true if this DisplayRealType is 'single' */
public isSingle();
/** return default value for this DisplayRealType */
public double getDefaultValue();
/** return true is a range of values is defined for
this DisplayRealType, and return the range in
range[0] and range[1]; range must be passed in
as a double[2] array */
public boolean getRange(double[] range);
public ScalarMap(ScalarType scalar, DisplayRealType display_scalar)
throws VisADException;
/** construct a ConstantMap with a double constant;
display_scalar may not be Animation, SelectValue, SelectRange
or IsoContour */
public ContantMap(double constant, DisplayRealType display_scalar)
throws VisADException;
/** construct a ConstantMap with a Real constant;
display_scalar may not be Animation, SelectValue, SelectRange
or IsoContour */
public ContantMap(Real constant, DisplayRealType display_scalar)
throws VisADException;
public ScalarType getScalar();
public DisplayRealType getDisplayScalar();
/** get the Control this ScalarMap is linked to;
the Control is constructed when this ScalarMap is linked to
a Display via an invocation of the Display's addMap method;
not all ScalarMaps have Controls, generally depending on the
ScalarMap's DisplayRealType */
public Control getControl();
/** return value is true if data (RealType) values are linearly
scaled to display (DisplayRealType) values;
if so, then values are scaled by:
display_value = data_value * scale_offset[0] + scale_offset[1];
(data[0], data[1]) defines range of data values (either passed
in to setRange or computed by autoscaling logic) and
(display[0], display[1]) defines range of display values;
scale_offset, data, display must each be passed in as
double[2] arrays */
public boolean getScale(double[] scale_offset, double[] data,
double[] display);
/** explicitly set the range of data (RealType) values;
if neither this nor setRangeByUnits is invoked, then the
range will be computed from the initial values of Data
objects linked to the Display by autoscaling logic;
if the range of data values is (0.0, 1.0), for example, this
method may be invoked with low = 1.0 and hi = 0.0 to invert
the display scale */
public void setRange(double low, double hi)
throws VisADException, RemoteException;
/** explicitly set the range of data (RealType) values according
to Unit conversion between this ScalarMap's RealType and
DisplayRealType (both must have Units and they must be
convertable; if neither this nor setRange is invoked, then
the range will be computed from the initial values of Data
objects linked to the Display by autoscaling logic */
public void setRangeByUnits() throws VisADException, RemoteException;
/** set enable / disable flag for axis scale for this
ScalarMap; DisplayScalar must be XAxis, YAxis or ZAxis */
public void setScaleEnable(boolean on);
/** set color of axis scales; color must be float[3] with red,
green and blue components; DisplayScalar must be XAxis,
YAxis or ZAxis */
public void setScaleColor(float[] color)
throws VisADException;
/** add a ScalarMapListener */
public void addScalarMapListener(ScalarMapListener listener);
/** remove a ScalarMapListener */
public void removeScalarMapListener(ScalarMapListener listener);
/** return an array of display (DisplayRealType) values by
linear scaling (if applicable) the data_values array
(RealType values) */
public float[] scaleValues(double[] data_values);
public float[] scaleValues(float[] data_values);
/** return an array of data (RealType) values by inverse
linear scaling (if applicable) the display_values array
(DisplayRealType values); this is useful for direct
manipulation and cursor labels */
public float[] inverseScaleValues(float[] display_values);
public double getConstant();
/** send a ScalarMapEvent to this ScalarMapListener */
public void mapChanged(ScalarMapEvent event)
throws VisADException, RemoteException;
/** get the ScalarMap that sent this ScalarMapEvent (or
a copy if the ScalarMap was on a different JVM) */
public ScalarMap getScalarMap();
(time -> ((line, element) -> (ir_radiance, vis_radiance)))The following code could be used to generate four different displays of the 'images' Data object:
// generate a traditional image display with ir radiances mapped
// to red, visible radiances mapped to green, constant blue,
// and animating over the time sequence;
// NOTE - this display can take advantage of texture mapping
// for efficiency
display1 = new DisplayImplJ3D("display1");
display1.addMap(new ScalarMap(time, Display.Animation));
display1.addMap(new ScalarMap(line, Display.YAxis));
display1.addMap(new ScalarMap(element, Display.XAxis));
display1.addMap(new ScalarMap(ir_radiance, Display.Red));
display1.addMap(new ScalarMap(vis_radiance, Display.Green));
display1.addMap(new ConstantMap(0.5, Display.Blue));
// visualize the images as contour lines of visible radiance
// on a 3-D terrain surface defined by ir radiances, with the
// contours colored by visible radiances and animating over
// the time sequence
display2 = new DisplayImplJ3D("display2");
display2.addMap(new ScalarMap(time, Display.Animation));
display2.addMap(new ScalarMap(line, Display.YAxis));
display2.addMap(new ScalarMap(element, Display.XAxis));
display2.addMap(new ScalarMap(ir_radiance, Display.ZAxis));
display2.addMap(new ScalarMap(vis_radiance, Display.IsoContour));
display2.addMap(new ScalarMap(vis_radiance, Display.RGB));
// visualize the images as 2-D scatter diagrams of ir
// radiance versus visible radiance, with points colored by
// time
display3 = new DisplayImplJ3D("display3");
display3.addMap(new ScalarMap(ir_radiance, Display.XAxis));
display3.addMap(new ScalarMap(vis_radiance, Display.YAxis));
display3.addMap(new ScalarMap(time, Display.RGB));
// generate a set of traditional image displays (i.e.,
// similar to display1) but with the time sequence stacked
// up in the vertical (ZAxis) rather than animated
display4 = new DisplayImplJ3D("display4");
display4.addMap(new ScalarMap(time, Display.ZAxis));
display4.addMap(new ScalarMap(line, Display.YAxis));
display4.addMap(new ScalarMap(element, Display.XAxis));
display4.addMap(new ScalarMap(ir_radiance, Display.Red));
display4.addMap(new ScalarMap(vis_radiance, Display.Green));
display4.addMap(new ConstantMap(0.5, Display.Blue));
Developers have the option to extend the DataRenderer and DisplayRenderer classes in order to customize Data displays. In fact, developers will need to extend the DataRenderer and DisplayRenderer classes for most extensions of the DisplayRealType and DisplayTupleType classes, because existing DataRenderer and DisplayRenderer classes will not know what to do with developer-defined DisplayRealType and DisplayTupleType classes (unless they are related to existing DisplayRealType and DisplayTupleType classes via CoordinateSystem References).
/** this is the default DataRenderer used by the addReference method
for DisplayImplJ3D */
public DefaultRendererJ3D();
/** this DataRenderer supports direct manipulation for Real,
RealTuple and Field Data objects (Field data objects must
have RealType or RealTupleType ranges and Gridded1DSet
domain Sets); no RealType may be mapped to multiple spatial
DisplayRealTypes; the RealType of a Real object must be
mapped to XAxis, YAxis or YAxis; at least one of the
RealType components of a RealTuple object must be mapped
to XAxis, YAxis or YAxis; the domain RealType and at
least one RealType range component of a Field object
must be mapped to XAxis, YAxis or YAxis */
public DirectManipulationRendererJ3D();
/** this is the default DisplayRenderer used by the
DisplayImplJ3D constructor;
it draws a 3-D cube around the scene;
the left mouse button controls the projection as
follows: mouse drag rotates in 3-D, mouse drag with
Shift down zooms the scene, mouse drag with Ctrl
translates the scene sideways;
the center mouse button activates and controls the
3-D cursor as follows: mouse drag translates the
cursor sideways, mouse drag with Shift translates
the cursor in and out, mouse drag with Ctrl rotates
scene in 3-D with cursor on;
the right mouse button is used for direct
manipulation by clicking on the depiction of a Data
object and dragging or re-drawing it;
cursor and direct manipulation locations are displayed
in RealType values;
BadMappingExceptions and UnimplementedExceptions are
displayed */
public DefaultDisplayRendererJ3D();
/** this DisplayRenderer supports 2-D only rendering;
is easiest to describe in terms of differences
from DefaultDisplayRendererJ3D: the cursor and box
around the scene are 2-D, the scene cannot be rotated,
the cursor cannot be translated in and out, and the
scene can be translated sideways with the left mouse
button with or without pressing the Ctrl key;
no RealType may be mapped to ZAxis or Latitude */
public TwoDDisplayRendererJ3D();
/** this is the default DataRenderer used by the addReference method
for DisplayImplJ2D */
public DefaultRendererJ2D();
/** this DataRenderer supports direct manipulation for Real,
RealTuple and Field Data objects (Field data objects must
have RealType or RealTupleType ranges and Gridded1DSet
domain Sets); no RealType may be mapped to multiple spatial
DisplayRealTypes; the RealType of a Real object must be
mapped to XAxis, YAxis or YAxis; at least one of the
RealType components of a RealTuple object must be mapped
to XAxis, YAxis or YAxis; the domain RealType and at
least one RealType range component of a Field object
must be mapped to XAxis, YAxis or YAxis */
public DirectManipulationRendererJ2D();
/** this is the default DisplayRenderer used by the
DisplayImplJ2D constructor;
it draws a 2-D box around the scene and a 2-D cursor;
the left mouse button controls the projection as
follows: mouse drag or mouse drag with Ctrl translates
the scene sideways, mouse drag with Shift down zooms
the scene; the center mouse button activates and
controls the 2-D cursor as follows: mouse drag
translates the cursor sideways; the right mouse button
is used for direct manipulation by clicking on the
depiction of a Data object and dragging or re-drawing
it; cursor and direct manipulation locations are
displayed in RealType values; BadMappingExceptions
and UnimplementedExceptions are displayed;
no RealType may be mapped to ZAxis, Latitude
or Alpha */
public DefaultDisplayRendererJ2D();
/** this returns a Vector of Strings from the BadMappingExceptions
and UnimplementedExceptions generated during the last invocation
of this DataRenderer's doAction method;
there is no need to over-ride this method, but it may be invoked
by DisplayRenderer */
public Vector getExceptionVector();
/** return an array of links to Data objects to be rendered;
Data objects are accessed by DataDisplayLink.getData() */
public DataDisplayLink[] getLinks();
/** transform linked Data objects into a display list, if
any Data object values have changed or relevant Controls
have changed; DataRenderers that assume the default
implementation of DisplayImpl.doAction can determine
whether re-transform is needed by:
(all_feasible && (any_changed || any_transform_control));
these flags are computed by the default DataRenderer
implementation of prepareAction;
the return boolean is true if the transform was done
successfully */
public abstract boolean doAction()
throws VisADException, RemoteException;
/** set isDirectManipulation = true if this DataRenderer
supports direct manipulation for its linked Data */
public void checkDirect()
throws VisADException, RemoteException;
/** clear any display list created by the most recent doAction
invocation */
public abstract void clearScene();
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowFunctionType;
these factories are invoked by the buildShadowType methods of
the MathType subclasses, which are invoked by
DataDisplayLink.prepareData, which is invoked by
DataRenderer.prepareAction */
public abstract ShadowType makeShadowFunctionType(
FunctionType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowRealTupleType */
public abstract ShadowType makeShadowRealTupleType(
RealTupleType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowRealType */
public abstract ShadowType makeShadowRealType(
RealType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowSetType */
public abstract ShadowType makeShadowSetType(
SetType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowTextType */
public abstract ShadowType makeShadowTextType(
TextType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** factory for constructing a subclass of ShadowType appropriate
for the graphics API, that also adapts ShadowTupleType */
public abstract ShadowType makeShadowTupleType(
TupleType type, DataDisplayLink link, ShadowType parent)
throws VisADException, RemoteException;
/** return true if a change in control requires re-transform;
this decision may use some values computed by
link.prepareData */
public boolean isTransformControl(Control control,
DataDisplayLink link);
/** set display box on or off */
public void setBoxOn(boolean on);
/** set color of display box */
public void setBoxColor(float r, float g, float b);
/** set color of display cursor */
public void setCursorColor(float r, float g, float b);
/** set color of display window background */
public void setBackgroundColor(float r, float g, float b);
/** return the DisplayImpl that this DisplayRenderer is attached to */
public DisplayImpl getDisplay();
/** return true is this is a 2-D DisplayRenderer */
public boolean getMode2D();
/** factory for constructing a subclass of Control appropriate
for the graphics API and for this DisplayRenderer;
invoked by ScalarMap when it is added to a Display */
public abstract Control makeControl(DisplayRealType type);
/** factory for constructing the default subclass of
DataRenderer for this DisplayRenderer */
public abstract DataRenderer makeDefaultRenderer();
/** return a double[3] array giving the cursor location in
(XAxis, YAxis, ZAxis) coordinates */
public double[] getCursor();
/** return Vector of Strings describing the cursor location */
public Vector getCursorStringVector();
/** set vector of Strings describing the cursor location
from the cursor location;
this is invoked when the cursor location changes or
the cursor display status changes */
public void setCursorStringVector();
/** set vector of Strings describing the cursor location;
this is invoked by direct manipulation renderers */
public void setCursorStringVector(Vector vector);
/** return true if type is legal for this DisplayRenderer;
for example, 2-D DisplayRenderers use this to disallow
mappings to ZAxis and Latitude */
public boolean legalDisplayScalar(DisplayRealType type);
/** set clipping bounds */ public void setClip(float xlow, float xhi, float ylow, float yhi);
/** get TransformGroup to which application can add
BranchGroups to the Java3D scene graph */
public TransformGroup getTrans();
Control
AnimationControl // animation stepping (interface)
AnimationSetControl // animation sampling
ColorControl // pseudo color table (for RGB, CMY, HSV, etc)
ColorAlphaControl // pseudo color-alpha table (for RGBA, etc)
ContourControl // iso-contour levels and intervals
FlowControl // flow rendering
Flow1Control // render 1st set of flow vectors
Flow2Control // render 2nd set of flow vectors
GraphicsModeControl // line width, point size, etc (interface)
ProjectionControl // 3-D rotation, scaling, translation (interface)
RangeControl // ranges of values
ShapeControl // array of shapes
ToggleControl // toggle other Controls on and off
ValueControl // individual value (interface)
TextControl // text plotting of Text values
Developers can extend the Control class to define new types of Controls for
new DisplayRealTypes (the binding from DisplayRealType to Control is defined in
the makeControl method of DisplayRenderer). Developers may also extend
subclasses of Control to define new forms of interaction for existing
DisplayRealTypes.AnimationControl, GraphicsModeControl, ProjectionControl and ValueControl are interfaces rather than classes, which must be implemented in a graphics-API- dependent way.
Instances of Control are linked to instances of ScalarMap. For some Control sub-classes, such as ProjectionControl and GraphicsModeControl, only one instance exists per Display. For other Control sub-classes, such as ContourControl, one instance exists per linked ScalarMap. Note that GraphicsModeControl is not linked to any instance of ScalarMap and every Display has a ProjectionControl even if no RealTypes are mapped to display spatial coordinates.
State changes in Controls may trigger a re-transformation of affected Data objects via their DataRenderers, or may not. For example, changes in a ProjectionControl will not generally trigger re-transformation, while changes in a ContourControl will trigger re-transformation of Data whose component RealTypes are mapped to IsoContour via the associated ScalarMap. DisplayRenderers are responsible for building any links from 3-D graphics APIs to Controls (e.g., so that mouse movements trigger changes in ProjectionControl to rotate, zoom and translate the 3-D display).
Classes that implement the ControlListener interface can be attached to Controls via their addControlListener method. Controls send ControlEvents to attached ControlListeners whenever they change state. ControlEvents include a reference to the Control that generated them, and Controls are Serializable, so that Displays on different JVMs (i.e., different computers or different Java interpreters on the same computer) can exchange ControlEvents and Controls to implement collaborative visualization.
/** add a ControlListener */ public void addControlListener(ControlListener listener); /** remove a ControlListener */ public void removeControlListener(ControlListener listener);
/** send a ControlEvent to this ControlListener */
public void controlChanged(ControlEvent event)
throws VisADException, RemoteException;
/** get the Control that sent this ControlEvent (or a copy
if the Control was on a different JVM) */
public Control getControl();
/** set the current ordinal step number */
public void setCurrent(int number)
throws VisADException, RemoteException;
/** set the current step by the value of the RealType
mapped to Display.Animation */
public void setCurrent(float value)
throws VisADException, RemoteException;
/** get the current ordinal step number */
public int getCurrent();
/** true for forward, false for backward */
public void setDirection(boolean direction)
throws VisADException, RemoteException;
/** set the dwell time for each step, in milliseconds */
public void setStep(int ms)
throws VisADException, RemoteException;
/** advance one step (forward or backward) */
public void takeStep()
throws VisADException, RemoteException;
/** turn on automatic stepping if on = true, turn it
off if on = false */
public void setOn(boolean on)
throws VisADException, RemoteException;
/** return true if automatic stepping is on */
public boolean getOn();
/** toggle automatic stepping between off and on */
public void toggle()
throws VisADException, RemoteException;
/** get Set of RealType values for animation steps */
public Set getSet();
/** define the color lookup by a Function, whose MathType must
have a 1-D domain and a 3-D RealTupleType range; the domain
and range Reals must vary over the range (0.0, 1.0) */
public void setFunction(Function function)
throws VisADException, RemoteException;
/** define the color lookup by an array of floats which must
have the form float[3][table_length]; values should be in
the range (0.0, 1.0) */
public void setTable(float[][] table)
throws VisADException, RemoteException;
/** define the color lookup by a Function, whose MathType must
have a 1-D domain and a 4-D RealTupleType range; the domain
and range Reals must vary over the range (0.0, 1.0) */
public void setFunction(Function function)
throws VisADException, RemoteException;
/** define the color lookup by an array of floats which must
have the form float[4][table_length]; values should be in
the range (0.0, 1.0) */
public void setTable(float[][] table)
throws VisADException, RemoteException;
/** set level for iso-surfaces */
public void setSurfaceValue(float value)
throws VisADException, RemoteException;
/ ** set parameters for iso-lines: draw lines for levels
between low and hi, starting at base, spaced by
interval */
public void setContourInterval(float interval, float low,
float hi, float base)
throws VisADException, RemoteException;
/ ** set array of unevenly spaced iso-line levels; if dash is
true then iso-lines for levels below base are dashed */
public void setLevels(float[] levels, float base, boolean dash)
throws VisADException, RemoteException;
/** enable contours */
public void enableContours(boolean on)
throws VisADException, RemoteException;
/** enable labels */
public void enableLabels(boolean on)
throws VisADException, RemoteException;
/** get contour parameters: bvalues[0] = contour enable,
bvalues[1] = labels enable, fvalues[0] = surface level,
fvalues[1] = interval, fvalues[2] = low, fvalues[3] = hi,
fvalues[4] = base; bvalues and fvalues must be passed in
as boolean[2] and float[5] */
public void getMainContours(boolean[] bvalues, float[] fvalues)
throws VisADException;
/** set scale length for flow vectors (default is 0.02f) */
public void setFlowScale(float scale)
throws VisADException, RemoteException;
/** if enable is true this will enable numerical
scales along display spatial axes; default is false */
public setScaleEnable(boolean enable)
throws VisADException, RemoteException;
/** set the width of line rendering; this is over-ridden by
ConstantMaps to Display.LineWidth; default is 1 */
public void setLineWidth(float width)
throws VisADException, RemoteException;
/** set the size for point rendering; this is over-ridden by
ConstantMaps to Display.PointSize; default is 1 */
public void setPointSize(float size)
throws VisADException, RemoteException;
/** if mode is true this will cause some rendering as points
rather than lines or surfaces; default is false */
public void setPointMode(boolean mode)
throws VisADException, RemoteException;
/** if enable is true this will enable use of texture
mapping, where appropriate; default is true */
public void setTextureEnable(boolean enable)
throws VisADException, RemoteException;
/** sets a graphics-API-specific transparency mode (e.g.,
SCREEN_DOOR, BLENDED); default is FASTEST */
public void setTransparencyMode(int mode)
throws VisADException, RemoteException;
/** sets a graphics-API-specific projection policy (e.g.,
PARALLEL_PROJECTION, PERSPECTIVE_PROJECTION);
default is PERSPECTIVE_PROJECTION */
public void setProjectionPolicy(int policy)
throws VisADException, RemoteException;
/** if transparent is true missing data are made transparent
rather than just black; default is false */
public void setMissingTransparent(boolean transparent)
throws VisADException, RemoteException;
/** size of flat areas in curved texture mapping; if size
is less than 1 then curved texture maps are disabled;
default size is 10 */
public void setCurvedSize(int size)
throws VisADException, RemoteException;
/** set the 4x4 matrix that defines the graphics
projection */
public void setMatrix(double[] matrix)
throws VisADException, RemoteException;
/** get the 4x4 matrix that defines the graphics
projection */
public double[] getMatrix();
/** set the range of selected values as (range[0], range[1]) */
public void setRange(float[] range)
throws VisADException, RemoteException;
/** return the range of selected values */
public float[] getRange();
/** set the SimpleSet that defines the mapping from RealType
values to indices into an array of shapes;
the domain dimension of set must be 1 */
public void setShapeSet(SimpleSet set)
throws VisADException, RemoteException;
/** set the shape associated with index;
the VisADGeometryArray class hierarchy defines various
kinds of shapes */
public void setShape(int index, VisADGeometryArray shape)
throws VisADException, RemoteException;
/** set the array of shapes associated with indices 0
through shapes.length; the VisADGeometryArray class
hierarchy defines various kinds of shapes */
public void setShapes(VisADGeometryArray[] shapes)
throws VisADException, RemoteException;
/** set the selected value */
public void setValue(float value)
throws VisADException, RemoteException;
/** return the selected value */
public float getValue();
/** set the size of characters; the default is 1.0 */
public void setSize(double size)
throws VisADException, RemoteException;
/** return the size */
public double getSize();
/** set the centering flag; if true, text will be centered at
mapped locations; if false, text will be to the right
of mapped locations */
public void setCenter(boolean center)
throws VisADException, RemoteException;
/** return the centering flag */
public boolean getCenter();
/** set the Font; in the initial release this has no effect */
public void setFont(Font font)
throws VisADException, RemoteException;
/** return the Font */
public Font getFont();
The DefaultDisplayRendererJ3D class supports the following mouse interactions using Java3D:
3-D cursor and direct manipulation locations are displayed in the upper left corner of the display window as RealType values with Units. BadMappingExceptions and UnimplementedExceptions are displayed at the bottom of the display window. Animation information is displayed in the lower right corner of the display window as RealType values with Units.
The TwoDDisplayRendererJ3D and DefaultDisplayRendererJ2D classes support similar mouse interactions, with the following exceptions: the scene cannot be rotated, the 3-D cursor cannot be translated in and out, and the scene may translated sideways with the left mouse button without the need to press the Ctrl key.
Note that direct manipulation rendering using display spatial coordinate transforms can only be done when the mappings of the Data object's MathType spans the full spatial dimensionality of the display (3-D or 2-D). This restriction avoids the ambiguity of finding the closest point to a line on a curved submanifold. Test number 40 of DisplayTest illustrates direct manipulation linking Cartesian and polar display coordinates.
This is only one interaction technique that can be built at an application level using VisAD. Many more are possible.
// create a Display
display1 = new DisplayImplJ3D("display1");
// map RealTypes to Display spatial axes
final ScalarMap map2lat = new ScalarMap(latitude, Display.YAxis);
display1.addMap(map2lat);
final ScalarMap map2lon = new ScalarMap(longitude, Display.XAxis);
display1.addMap(map2lon);
final ScalarMap map2vis = new ScalarMap(vis_radiance, Display.ZAxis);
display1.addMap(map2vis);
// link a Data object to Display
display1.addReference(ref_data, null);
// wait for Display auto-scaling (it would be more proper to wait
// until the getRange() invocations below return non-Missing values)
try {
Thread.sleep(2000);
}
catch (InterruptedException e) {
}
// get ranges of values mapped to Display spatial axes
double[] range1lat = map2lat.getRange();
double[] range1lon = map2lon.getRange();
double[] range1vis = map2vis.getRange();
// create RealTuple Data objects that will be displayed at opposite
// corners of 3-D Display box
RealTuple direct_low = new RealTuple(new Real[]
{new Real(RealType.Latitude, range1lat[0]),
new Real(RealType.Longitude, range1lon[0]),
new Real(vis_radiance, range1vis[0])});
RealTuple direct_hi = new RealTuple(new Real[]
{new Real(RealType.Latitude, range1lat[1]),
new Real(RealType.Longitude, range1lon[1]),
new Real(vis_radiance, range1vis[1])});
// enable spatial axis scale displays
mode = display1.getGraphicsModeControl();
mode.setScaleEnable(true);
// color direct_low and direct_hi tuples yellow and make them
// 5 pixels wide
mode.setPointSize(5.0f);
ConstantMap[][] maps = {{new ConstantMap(1.0f, Display.Red),
new ConstantMap(1.0f, Display.Green),
new ConstantMap(0.0f, Display.Blue)}};
// link direct_low to Display with direct manipulation
final DataReferenceImpl ref_direct_low =
new DataReferenceImpl("ref_direct_low");
ref_direct_low.setData(direct_low);
display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {ref_direct_low}, maps);
// link direct_hi to Display with direct manipulation
final DataReferenceImpl ref_direct_hi =
new DataReferenceImpl("ref_direct_hi");
ref_direct_hi.setData(direct_hi);
display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {ref_direct_hi}, maps);
// construct a computational Cell that re-scales Display spatial
// axes to keep direct_low and direct_hi at corners of 3-D box
cell = new CellImpl() {
public void doAction() throws VisADException, RemoteException {
RealTuple low = (RealTuple) ref_direct_low.getData();
RealTuple hi = (RealTuple) ref_direct_hi.getData();
map2lat.setRange(((Real) low.getComponent(0)).getValue(),
((Real) hi.getComponent(0)).getValue());
map2lon.setRange(((Real) low.getComponent(1)).getValue(),
((Real) hi.getComponent(1)).getValue());
map2vis.setRange(((Real) low.getComponent(2)).getValue(),
((Real) hi.getComponent(2)).getValue());
}
};
// link cell to direct_low and direct_hi, so that its doAction
// method fires whenever the user shanges their values via
// direct manipulation
cell.addReference(ref_direct_low);
cell.addReference(ref_direct_hi);
Now, whenever the user tries to drag either of the yellow squares away from
the corners of the 3-D box, the cell will re-scale the Display spatial axes to
keep them at the corners of the box. This creates interactive scaling controls
embedded in the display.Furthermore, there is one ShadowType class hierarchy in the visad package, another in the visad.java3d package (all subclasses of ShadowType that adapt the corresponding class in the visad package), and presumably there will be one for each graphics API. In fact, ShadowTypes are constructed by factory methods in DataRenderer, so each DataRenderer could define a ShadowType sub-class hierarchy.
The real work of transforming Data objects into displays is done by the doTransform method of ShadowType. Other methods of ShadowType, such as checkIndices and testIndices, are involved in analyzing MathTypes and ScalarMaps to determine how Data objects should be transformed. It is all very complex but does define a working approach to managing the flexibility and extensibility of the VisAD visualization architecture. However, developers do have the option of ignoring the entire structure of ShadowTypes by over-riding the doAction method of Display.
DisplayEvent.MOUSE_PRESSED (a mouse button is pressed), DisplayEvent.MOUSE_PRESSED_LEFT (the left mouse button was pressed), DisplayEvent.MOUSE_PRESSED_CENTER (the center mouse button was pressed), DisplayEvent.MOUSE_PRESSED_RIGHT (the right mouse button was pressed), DisplayEvent.TRANSFORM_DONE (end of transforming data objects into renderable scenes) DisplayEvent.FRAME_DONE (end of rendering a scene), DisplayEvent.MOUSE_RELEASED (a mouse button is released), DisplayEvent.MOUSE_RELEASED_LEFT (the left mouse button is released), DisplayEvent.MOUSE_RELEASED_CENTER (the center mouse button is released), DisplayEvent.MOUSE_RELEASED_RIGHT (the right mouse button is released), DisplayEvent.MAP_ADDED (addMap() method called), DisplayEvent.MAPS_CLEARED (clearMaps() method called), DisplayEvent.REFERENCE_ADDED (addReference() method called), DisplayEvent.REFERENCE_REMOVED (removeReference() method called)DisplayEvents include a reference to the Display that generated them, which is either a local DisplayImpl or a RemoteDisplay for Displays on different JVMs (i.e., on different computers or on different Java interpreters on the same computer).
Note that VisAD enables applications to easily construct collaborative displays, as described in Section 6.4. These are displays on different computers that are visually identical and maintain that consistency in response to changes by users and application programs.
/** construct a DisplayImpl for Java3D with a
DefaultDisplayRendererJ3D, in a JFC JPanel */
public DisplayImplJ3D(String name)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D with a
DefaultDisplayRendererJ3D, in a JFC Jpanel;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(String name, GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D with a non-default
DisplayRenderer, in a JFC Jpanel */
public DisplayImplJ3D(String name, DisplayRendererJ3D renderer)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D with a non-default
DisplayRenderer, in a JFC Jpanel;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(String name, DisplayRendererJ3D renderer,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME */
public DisplayImplJ3D(String name, int api)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(String name, int api,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D with a non-default
DisplayRenderer;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME */
public DisplayImplJ3D(String name, DisplayRendererJ3D renderer,
int api) throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D with a non-default
DisplayRenderer;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(String name, DisplayRendererJ3D renderer,
int api, GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a DefaultDisplayRendererJ3D, in a JFC JPanel */
public DisplayImplJ3D(RemoteDisplay rmtDpy)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a DefaultDisplayRendererJ3D, in a JFC Jpanel;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(RemoteDisplay rmtDpy,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a non-default DisplayRenderer, in a JFC Jpanel */
public DisplayImplJ3D(RemoteDisplay rmtDpy,
DisplayRendererJ3D renderer)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a non-default DisplayRenderer, in a JFC Jpanel;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(RemoteDisplay rmtDpy,
DisplayRendererJ3D renderer,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME */
public DisplayImplJ3D(RemoteDisplay rmtDpy, int api)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(RemoteDisplay rmtDpy, int api,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a non-default DisplayRenderer;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME */
public DisplayImplJ3D(RemoteDisplay rmtDpy,
DisplayRendererJ3D renderer, int api)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java3D remotely collaborating with
rmtDpy, with a non-default DisplayRenderer;
in a JFC JPanel if api == DisplayImplJ3D.JPANEL and
in an AppletFrame if api == DisplayImplJ3D.APPLETFRAME;
config can be used to create a stereo display (see
visad/examples/TestStereo.java for an example) */
public DisplayImplJ3D(RemoteDisplay rmtDpy,
DisplayRendererJ3D renderer, int api,
GraphicsConfiguration config)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D with a
DefaultDisplayRendererJ2D, in a JFC JPanel */
public DisplayImplJ2D(String name)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D with a non-default
DisplayRenderer, in a JFC JPanel */
public DisplayImplJ2D(String name, DisplayRendererJ2D renderer)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D with a
DefaultDisplayRendererJ2D;
in a JFC JPanel if api == DisplayImplJ2D.JPANEL */
public DisplayImplJ2D(String name, int api)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D with a non-default
DisplayRenderer;
in a JFC JPanel if api == DisplayImplJ2D.JPANEL */
public DisplayImplJ2D(String name, DisplayRendererJ2D renderer,
int api) throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D for offscreen rendering,
with size geiven by width and height; getComponent() of this
returns null, but display is accesible via getImage() */
public DisplayImplJ2D(String name, int width, int height)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D for offscreen rendering
with a non-default isplayReenderer;
with size geiven by width and height; getComponent() of this
returns null, but display is accesible via getImage() */
public DisplayImplJ2D(String name, DisplayRendererJ2D renderer,
int width, int height)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D remotely collaborating with
rmtDpy, with a DefaultDisplayRendererJ2D, in a JFC JPanel */
public DisplayImplJ2D(RemoteDisplay rmtDpy)
throws VisADException, RemoteException;
/** construct a DisplayImpl for Java2D remotely collaborating with
rmtDpy, with a non-default DisplayRenderer, in a JFC JPanel */
public DisplayImplJ2D(RemoteDisplay rmtDpy,
DisplayRendererJ2D renderer)
throws VisADException, RemoteException;
/** return the name of this Display; this method is inherited from
Action */
public String getName()
throws VisADException, RemoteException;
/** link map to this Display; this method may not be invoked
after any links to DataReferences have been made */
public void addMap(ScalarMap map)
throws VisADException, RemoteException;
/** clear all links to maps from this Display */
public void clearMaps()
throws VisADException, RemoteException;
/** link ref to this Display; this method may only be invoked
after all links to ScalarMaps have been made */
public void addReference(DataReference ref)
throws VisADException, RemoteException;
/** link ref to this Display; this method may only be invoked
after all links to ScalarMaps have been made;
the ConstantMap array applies only to rendering ref */
public void addReference(DataReference ref, ConstantMap[] maps)
throws VisADException, RemoteException;
/** remove link to ref; if ref was added as part of a DataReference
array passed to addReferences, remove links to all of them */
public void removeReference(DataReference ref)
throws VisADException, RemoteException;
/** remove all DataReference links */
public void removeAllReferences()
throws VisADException, RemoteException;
/** link refs to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
the maps[i] array applies only to rendering refs[i];
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer,
DataReference[] refs, ConstantMap[][] maps)
throws VisADException, RemoteException;
/** link refs to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer, DataReference[] refs)
throws VisADException, RemoteException;
/** link ref to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
the maps array applies only to rendering ref;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer,
DataReference ref, ConstantMap[] maps)
throws VisADException, RemoteException;
/** link ref to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer, DataReference ref)
throws VisADException, RemoteException;
/** return the JPanel or AppletPanel this DisplayImpl uses;
returns null for an offscreen DisplayImpl */
public Component getComponent();
/** return a captured image of the display */
public BufferedImage getImage();
/** return the DisplayRenderer associated with this DisplayImpl */
public DisplayRenderer getDisplayRenderer();
/** return the ProjectionControl associated with this DisplayImpl */
public ProjectionControl getProjectionControl();
/** return the GraphicsModeControl associated with this DisplayImpl */
public GraphicsModeControl getGraphicsModeControl();
/** add a DisplayListener */
public void addDisplayListener(DisplayListener listener);
/** remove a DisplayListener */
public void removeDisplayListener(DisplayListener listener);
/** re-apply auto-scaling of ScalarMap ranges next time
Display is triggered */
public void reAutoScale();
/** if auto is true, re-apply auto-scaling of ScalarMap ranges
every time Display is triggered */
public void setAlwaysAutoScale(boolean auto);
/** disable the action of this DisplayImpl, but respond to any
accumulated events after it is re-enabled; this method does
not return until actions have ceased in this DisplayImpl */
public void disableAction();
/** re-enable this previously disabled DisplayImpl, and respond
to any accumulated events */
public void enableAction();
/** create a projection matrix appropriate for this graphics API
from x, Y and Z rotation angles, from a scale factor, and from
X, Y and Z translation amounts;
these creates the matrix format used by the getMatrix and
setMatrix methods of ProjectionControl;
note DisplayImplJ3D returns an array of length 16 (4 x 4 matrix)
and DisplayImplJ2D returns an array of length 6 (2 x 3 matrix) */
public double[] make_matrix(double rotx, double roty, double rotz,
double scale, double transx,
double transy, double transz);
/** return the product of matrices a and b, according to the matrix
format for this graphics API */
public double[] matrix_multiply(double[] a, double[] b);
/** wait for milliseconds; this is deprecated, use
'new visad.util.Delay(milliseconds)' instead */
public static void delay(int milliseconds)
throws VisADException;
/** link refs to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
the maps[i] array applies only to rendering refs[i];
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer,
DataReference[] refs, ConstantMap[][] maps)
throws VisADException, RemoteException;
/** link refs to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer, DataReference[] refs)
throws VisADException, RemoteException;
/** link ref to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
the maps array applies only to rendering ref;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer,
DataReference ref, ConstantMap[] maps)
throws VisADException, RemoteException;
/** link ref to this Display using the non-default renderer;
this method may only be invoked after all links to ScalarMaps
have been made;
this is a method of DisplayImpl and RemoteDisplayImpl rather
than Display - see Section 6.1 for more information */
public void addReferences(DataRenderer renderer, DataReference ref)
throws VisADException, RemoteException;
/** send a DisplayEvent to this DisplayListener */
public void displayChanged(DisplayEvent event)
throws VisADException, RemoteException;
/** get the DisplayImpl that sent this DisplayEvent (or
a RemoteDisplay reference to it if the Display was on
a different JVM) */
public Display getDisplay();
/** get the ID type of this event; legal ID's are
DisplayEvent.MOUSE_PRESSED, DisplayEvent.MOUSE_PRESSED_CENTER
DisplayEvent.TRANSFORM_DONE and DisplayEvent.RENDER_DONE */
public int getId();
/** get the window X coordinate if this is a mouse pressed event */
public int getX();
/** get the window Y coordinate if this is a mouse pressed event */
public int getY();
The PlotText.render_label method, documented in Section 4.7.2, is useful for generating shapes from text Strings. The ShapeControl.setShapeSet method can be used to define a quantization of real values, and shapes can be generated from numerical strings of quantization values. The start argument to PlotText.render_label method can be used to generate different offsets for text plots of values of different RealTypes. This could be used to generate traditional station plots from meteorological data.
If the Set argument to setShapeSet has length = 1 (i.e., just one member) then all RealType values map to the VisADGeometryArray shape at index = 0.
For examples on how to use Shape, see examples/DisplayTest.java cases 46 and 47.
` public int vertexCount; public float[] coordinates; public float[] normals; public byte[] colors;Only vertexCount and coordinates must be set, and the length of coordinates must be 3 times vertexCount. Each group of 3 coordinates values defines the XAxis, YAxis and ZAxis (ignored for Java2D displays) spatial coordinates of a vertex. Spatial coordinates vary from -1.0f to +1.0f in the VisAD display "box". In general, the coordinates of shapes should be centered around the origin (0.0f, 0.0f, 0.0f) and scaled appropriately relative to the "box" dimensions. Use RealTypes mapped to spatial DisplayRealTypes to determine absolute shape locations, and RealTypes mapped to ShapeScale to determine relative shape sizes.
For triangles or quads in Java3D, normals must be set and have the same length as coordinates. Normals should be normalized to length 1.0f.
If colors is set its length must be 3 times vertexCount for Red, Green and Blue color components or 4 times vertexCount to also include Alpha (transparency, in Java3D only). Colors values are unsigned bytes because these are used by Java3D, but NOTE that unsigned bytes are not a supported primitive type of Java. If colors is not set, shape colors are determined by RealTypes mapped to color DisplayRealTypes.
The subclasses of VisADGeometryArray are:
VisADPointArray - each vertex is rendered as a point VisADLineArray - each pair of vertices is rendered as a line VisADTriangleArray - each three vertices is rendered as a triangle VisADQuadArray - each four vertices is rendered as a quadrangle VisADLineStripArray - see description below VisADTriangleStripArray - see description below VisADIndexedTriangleStripArray - see description belowThese classes all have no-argument constructors, relying on public direct access to their variables. These classes behave like the corresponding classes (just remove "VisAD" from the class name) in the javax.media.j3d package (i.e., Java3D). Note that for VisADLineArray, VisADTriangleArray and VisADQuadArray vertexCount must be a multiple of 2, 3 and 4 respectively. For VisADLineStripArray, VisADTriangleStripArray and VisADIndexedTriangleStripArray sequences of vertices are rendered as strips of lines and triangles, as described for the LineStripArray, TriangleStripArray and IndexedTriangleStripArray classes in Java3D.
/** create a VisADLineArray rendering of string, located at
start, with characters separated by base and character
vertical in the up direction (start, base and up are all
double[3] arrays); center text at start if center is true */
public static VisADLineArray render_label(String string,
double[] start, double[] base, double[] up, boolean center);
Note that the RemoteSlaveDisplayImpl delivers mouse events back to the DisplayImpl on the server, allowing the user to interact with the display as if it were a local DisplayImpl.
public RemoteSlaveDisplayImpl(RemoteDisplay d)
throws VisADException, RemoteException;
/** get a component of the display that can be added to a GUI */ public JComponent getComponent();
The VisAD system does not include class hierarchies for defining computations, the way it does for defining Data and Displays. This is because the Java programming language defines an adequate set of structures for defining computations, including the ability to link to functions written in other languages (e.g., C and Fortran) via the Java Native Interface (JNI).
However, the VisAD Data classes do define methods for basic arithmetical and mathematical operations. These include all the Java primitive operations (e.g., add, subtract) and the operations of the java.lang.Math class (e.g., sqrt, sin, max), as described in Section 3.2.2. They also include operations specific to Data subclasses, such as Tuple component access and Function evaluation and resampling, as described in Sections 3.2.5 and 3.2.7.
public CellImpl(); /** the name String can be useful for debugging */ public CellImpl(String name);
/** return the name of this Cell; this method is inherited from
Action */
public String getName()
throws VisADException, RemoteException;
/** this defines the computation performed by this Cell;
it is invoked whenever linked Data objects change */
public abstract void doAction()
throws VisADException, RemoteException;
/** link ref to this Cell */
public void addReference(DataReference ref)
throws VisADException, RemoteException;
/** remove link to ref */
public void removeReference(DataReference ref)
throws VisADException, RemoteException;
/** remove all DataReference links */
public void removeAllReferences()
throws VisADException, RemoteException;
/** set a non-triggering link to a DataReference; this is
used to give the Cell access to Data without triggering
the Cell's doAction whenever the Data changes;
these 'other' DataReferences are identified by their
integer index */
public void setOtherReference(int index, DataReference ref)
throws VisADException, RemoteException;
/** return the non-triggering link to a DataReference
identified by index */
public DataReference getOtherReference(int index)
throws VisADException, RemoteException;
/** disable the action of this CellImpl, but respond to any
accumulated events after it is re-enabled; this method does
not return until actions have ceased in this CellImpl */
public void disableAction();
/** re-enable this previously disabled CellImpl, and respond
to any accumulated events */
public void enableAction();
/** increase the current maximum limit on the number of Java
Threads used for all ActionImpls; the default maximum is 10
and num cannot be less than the current maximum */
public void setThreadPoolMaximum(int num)
throws Exception;
` In order to adapt to RMI, the Data class hierarchy is replicated four times:
1. interface Data
/ \
3. class DataImpl 2. interface RemoteData
implements Data, extends Remote, Data
Serializable |
4. class RemoteDataImpl
extends UnicastRemoteObject
implements RemoteData
(adapts DataImpl)
* Application developers have the freedom to use remote objects wherever they like.This same replication of classes into four distinct hierarchies is also applied to DataReference (i.e., DataReference, RemoteDataReference, DataReferenceImpl, RemoteDataReferenceImpl) and to the Action class hierarchy (which includes Display). This allows Displays to be linked to remote DataReference objects to support remote visualization, and allows connections between remote Displays to support collaborative visualization. It is even possible that the components of a Tuple or the range samples of a Field may reside on multiple remote machines - note however that application developers should exploit such freedom carefully.
When developers need to distinguish between local and remote objects, local objects can be accessed using the classes in 3, and remote objects can be accessed using the interfaces in 2. Objects that are going to accessed remotely should use the constructors of the classes in 4, but declared using the interfaces in 1 or 2.
The addReference method of Display and Cell (inherited from Action) is invoked by applications to create the network of Data, Display and computational Cell objects. When the addReference method is invoked for RemoteDisplays and RemoteCells, the arguments should be instances of RemoteDataReference. This is because a local DataReferenceImpl will be passed by copy and the RemoteDisplay or RemoteCell will be linked with the copy rather than the intended DataReference. Applications can easily construct RemoteDataReferenceImpl objects for any local DataReferenceImpl objects that they need to link to RemoteDisplays or RemoteCells. Similarly, when the addReference method is invoked for local DisplayImpl and CellImpl objects, the argument should be a local DataReferenceImpl object. The general rule is:
* Connect local to local and remote to remote using addReference.In contrast, the addReferences method of DisplayImpl and RemoteDisplayImpl can accept a mix RemoteDataReferenceImpl and local DataReferenceImpl arguments. However, the addReferences method is not defined for the RemoteDisplay interface (or for the Display interface) and hence may not be invoked remotely. It can only be invoked locally so local DataReferenceImpl arguments are not copied. That is, the addReferences method can be used to create links between Data and Displays that are on different JVMs (i.e., different computers or different Java interpreters running on the same computer), but may only be invoked on the JVM of the Display.
The rule about connecting local to local and remote to remote also applies to the setData method of DataReference that creates links between DataReference objects and Data objects. In particular, only local DataImpl objects may be the argument of the setData method of a local DataReferenceImpl object. However, both local and remote Data objects may be argument of the setData method of a RemoteDataReference object. This is because many Data subclasses can only be local (e.g., Real, RealTuple, Tuple, Set). Note, however, that when a local DataImpl object is the argument of the setData method of a RemoteDataReference object, then a copy of that argument is passed to the JVM of the RemoteDataReference object. This can lead to the following problem if the local DataImpl argument is mutable (i.e., a FieldImpl or a FlatField): the application may modify the local DataImpl object but these changes will not be reflected in the copy that is actually linked to the RemoteDataReference object. Developers of distributed applications should remember that:
* Local FieldImpl and FlatField arguments to RemoteDataReference.setData are
dangerous.
A Data object may have sub-objects residing on multiple JVMs. This is
because the component arguments to the Tuple constructor and the range sample
arguments to the FieldImpl constructor are declared as Data and may be either
local or remote. This should be used with care. It can result in very poor
performance. Furthermore, data modification events are not propagated from sub-
objects to parent objects on different JVMs.The Data, DataReference, Display and Cell classes all support remote access. However, only the Data class and its associated metadata classes also support copying between JVMs. Thus DataReference, Display and Cell objects are fixed to the machine where they are created (although their methods can be invoked remotely). Copying Display objects makes no sense, since they are attached to a physical display device. Cell objects should not be copied between JVMs since they may include calls to functions written in other programming languages which are not generally portable between machines. Copying DataReferences is dangerous because they define data identities in applications.
Developers should think about distributed applications as consisting of DataReference, Display, Cell and user interface objects with fixed locations, and which communicate by exchanging Data and ThingChangedEvents (ThingChangedEvents are invisible to applications - they are used to notify Displays and Cells when Data values change).
Finally we offer a few general cautions for programming with distributed objects. First, beware of static variables that are not constant across all JVMs in any Serializable class. When objects are copied to new JVMs they will encounter new values for non-constant static variables. For example, if you want to enforce that every instance of a class have a unique name String, you would do this with a static Vector of names. But when instances are copied between JVMs there is no way to enforce that names are unique.
Similarly, beware of using '==' or '!=' tests between instances of any Serializable class. Rather, use the equals method and explicitly define the conditions for equality. For example, an object should probably be equal to a clone of itself.
The GoesCollaboration application described in Section 12.3 and listed in Appendix B includes examples of how RemoteServerImpl and java.rmi.Naming should be used.
Note that remote implementation classes (in VisAD these have names matching Remote*Impl) require a second compilation step to generate RMI stub and skel classes. In JDK this second compilation step is done with the rmic compiler.
Note also that an RMI server must be running on a machine where applications invoke the java.rmi.Naming.rebind method. In JDK this RMI server is rmiregistry.
/** construct a RemoteServerImpl and initialize it with
an array of RemoteDataReferenceImpls */
public RemoteServerImpl(RemoteDataReferenceImpl[] refs)
throws RemoteException;
/** return the RemoteDataReference with index on this
RemoteServer, or null */
public RemoteDataReference getDataReference(int index)
throws RemoteException;
/** return the RemoteDataReference with name on this
RemoteServer, or null */
public RemoteDataReference getDataReference(String name)
throws VisADException, RemoteException;
/** return an array of all RemoteDataReferences on this
RemoteServer, or null */
public RemoteDataReference[] getDataReferences()
throws VisADException, RemoteException;
/** set one RemoteDataReference in the array on this
RemoteServer (and extend length of array if necessary) */
public void setDataReference(int index, RemoteDataReference ref)
throws VisADException;
/** set array of all RemoteDataReferences on this RemoteServer */
public void setDataReferences(RemoteDataReference[] refs);
// construct three Data objects,
FunctionType field_type = new FunctionType(reala, realb);
FlatField field = FlatField.makeField(field_type, 64, false);
Real real = new Real(reala, 2.0);
Real[] reals3 = {new Real(reala, 1.0), new Real(realb, 2.0),
new Real(realc, 1.0)};
RealTuple real_tuple = new RealTuple(reals3);
// construct a Display
display1 = new DisplayImplJ3D("display1");
// map RealTypes to Display spatial axes
display1.addMap(new ScalarMap(reala, Display.XAxis));
display1.addMap(new ScalarMap(realb, Display.YAxis));
display1.addMap(new ScalarMap(realc, Display.ZAxis));
// 5 pixel size for Real and RealTuple objects
mode = display1.getGraphicsModeControl();
mode.setPointSize(5.0f);
// construct DataReferences for three Data objects and link them
// to Display via DirectManipulationRendererJ3Ds
ref_real = new DataReferenceImpl("ref_real");
ref_real.setData(real);
display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {ref_real});
ref_real_tuple = new DataReferenceImpl("ref_real_tuple");
ref_real_tuple.setData(real_tuple);
display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {ref_real_tuple});
ref_field = new DataReferenceImpl("ref_field");
ref_field.setData(field);
display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {ref_field});
// create RemoteDataReferences
RemoteDataReferenceImpl[] rem_data_refs =
new RemoteDataReferenceImpl[3];
rem_data_refs[0] = new RemoteDataReferenceImpl(ref_field);
rem_data_refs[1] = new RemoteDataReferenceImpl(ref_real);
rem_data_refs[2] = new RemoteDataReferenceImpl(ref_real_tuple);
// construct a RemoteServer for the RemoteDataReferences
RemoteServerImpl obj = new RemoteServerImpl(rem_data_refs);
// and bind it to a URL
Naming.rebind("//:/RemoteServerTest", obj);
Once the server is running, any number of clients can connect and share
access to the same set of three Data objects. Here is the client code:
// lookup RemoteServer by URL specified in domain String
RemoteServer remote_obj = (RemoteServer) Naming.lookup(domain);
// get three RemoteDataReferences from RemoteServer
RemoteDataReference field_ref = remote_obj.getDataReference(0);
RemoteDataReference real_ref = remote_obj.getDataReference(1);
RemoteDataReference real_tuple_ref = remote_obj.getDataReference(2);
// get RealTupleType of real_tuple Data object
dtype = (RealTupleType) real_tuple_ref.getData().getType();
// construct a Display
display1 = new DisplayImplJ3D("display");
// map RealType components of real_tuple to Display spatial axes
display1.addMap(new ScalarMap((RealType) dtype.getComponent(0),
Display.XAxis));
display1.addMap(new ScalarMap((RealType) dtype.getComponent(1),
Display.YAxis));
display1.addMap(new ScalarMap((RealType) dtype.getComponent(2),
Display.ZAxis));
// 5 pixel size for Real and RealTuple objects
mode = display1.getGraphicsModeControl();
mode.setPointSize(5.0f);
// construct RemoteDisplay to link to RemoteDataReferences
// (recall that we must connect remote to remote)
RemoteDisplayImpl remote_display1 = new RemoteDisplayImpl(display1);
remote_display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {real_ref});
remote_display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {real_tuple_ref});
remote_display1.addReferences(new DirectManipulationRendererJ3D(),
new DataReference[] {field_ref});
Another way is to construct a RemoteSlaveDisplay, as described in Section 4.8. A RemoteDisplayImpl simply receives 2-D images each time its server DisplayImpl updates, and sends all MouseEvents back to the server DisplayImpl. RemoteSlaveDispays are useful for clients that lack sufficient memory, computing or graphics resources to visualize an application’s data, so must rely on a server for these resources.
A given file or other data object can generally be interpreted as many different VisAD MathTypes. For example, data with the following MathType:
(time -> (temperature, pressure))could also be read as:
((time -> temperature), (time -> pressure))The first MathType is usually preferable, since it makes it clear that the temperature and pressure Fields have the same time sampling. However, in some cases the second MathType may be preferred, for example to combine this with other data having the second MathType (and possibly temperatures and pressures with unequal time samplings).
Similarly, data with the MathType:
(latitude -> (longitude -> pressure))could also be read as:
((latitude, longitude) -> pressure)Again, the first MathType is usually preferable, since it makes it clear that the domain sampling Set of (latitude, longitude) can be factored into a product of latitude samples and longitude samples. However, the second MathType may be preferable in order to combine this data with other data whose (latitude, longitude) sampling cannot be factored, or whose domain MathType is (row, column) with a CoordinateSystem whose Reference is (latitude, longitude).
Thus our approach is to develop a variety of adapters for each data format, in order to give application developers and end users a choice of how to interpret data in terms of the VisAD data model. However, in the initial release of VisAD, however, there is only a single adapter per data format.
Adapters initially exist for FITS, netCDF, HDF-EOS, GIF and Vis5D file formats. The contacts for help with each file format are:
FITS Dave Glowacki dglo@ssec.wisc.edu netCDF Steve Emmerson steve@unidata.ucar.edu HDF-EOS Tom Rink rink@ssec.wisc.edu GIF Dave Glowacki dglo@ssec.wisc.edu Vis5D Bill HIbbard hibbard@facstaff.wisc.edu
The MathType of any Data object is returned by the getType method of Data. MathTypes have tree structures that can be recursively "parsed" with code like:
MathType type = data.getType();
if (type instanceof FunctionType) {
RealTupleType domain = ((FunctionType) type).getDomain;
MathType range = ((FunctionType) type).getRange();
// recursively analyze domain and range
}
else if (type instanceof RealTupleType) {
int dimension = ((TupleType) type).getDimension();
RealType[] types = new RealType[dimension];
for (int i=0; i<dimension; i++) {
types[i] = (RealType) ((TupleType) type).getComponent(i);
}
// recursively analyze types
}
else if (type instanceof TupleType) {
int dimension = ((TupleType) type).getDimension();
MathType[] types = new MathType[dimension];
for (int i=0; i<dimension; i++) {
types[i] = ((TupleType) type).getComponent(i);
}
// recursivley analyze types
}
else if (type instanceof RealType) {
// this is a leaf in the MathType "tree"
// map it to a DisplayRealType, get its default Unit, etc
}
else if (type insatnceof TextType) {
// this is a leaf in the MathType "tree"
}
Most applications will try to fit MathTypes into broad categories, such as
"image", "grid" or "table". Data displays are defined by ScalarMaps (described
in Section 4.1) involving the RealTypes that are extracted from the MathTypes of
Data to be displayed. Applications may define general policies for constructing
ScalarMaps for each broad category of MathTypes. Section 4.1.1 describes some
general guidelines for defining ScalarMaps.Other metadata such as Units, CoordinateSystems, Sets, ErrorEstimates and missing data indicators can be extracted from Data objects using methods such as:
boolean Data.isMissing() Unit Real.getUnit() ErrorEstimate Real.getError() Unit[] RealTuple.getTupleUnits() CoordinateSystem RealTuple.getCoordinateSystem() ErrorEstimate[] RealTuple.getErrors() Set Field.getDomainSet() Unit[] Field.getDomainUnits() CoordinateSystem Field.getDomainCoordinateSystem() Unit[] FlatField.getRangeUnits() CoordinateSystem FlatField.getRangeCoordinateSystem() CoordinateSystem FlatField.getRangeCoordinateSystem(int index) ErrorEstimate[] FlatField.getRangeErrors()These methods are documented in the appropriate sub-sections of Section 3.2.
Each file format may include multiple sub-classes of Form, each defining a different policy for how data objects are adapted to the VisAD Data and metadata classes. For example, different Form sub-classes may return Data objects with different MathTypes for the same external data object.
The general design for data form adapters is unfinished, and will be further elaborated in later versions of VisAD. Furthermore, the functionality of current adapters varies between different file formats.
/** open a data object specified by a String id, commonly a
file name, and return a DataImpl that adapts it to the
VisAD Data and metadata API */
public DataImpl open(String id)
throws BadFormException, IOException, VisADException;
/** open a data object specified by a URL, and return a DataImpl
that adapts it to the VisAD Data and metadata API */
public DataImpl open(URL url)
throws BadFormException, IOException, VisADException;
/** store data in an external data object specified by a
String id, commonly a file name; only over-write an
existing data object if replace is true */
public void save(String id, Data data, boolean replace)
throws BadFormException, IOException, VisADException,
RemoteException;
FitsForm has the constructor:
public FitsForm();A FitsForm instance can open any number of FITS files.
Plain has the constructor:
public Plain();A Plain instance can open and save any number of netCDF files.
Plain leaves most netCDF arrays unfactored. However, it will factor netCDF arrays whose outermost dimension is time (recognized by units convertable with seconds, or by the name 'time'). Thus, rather than returning a Data object with the MathType:
((time, latitude, longitude, altitude) -> temperature)it will factor this into:
(time -> ((latitude, longitude, altitude) -> temperature))This permits time to be mapped to Display.Animation (it could not be mapped to Animation in the unfactored MathType because the Display could not be guaranteed that it will be able to factor a Set of time samples for animation steps from the unfactored MathType).
The HDF-EOS file adapter invokes native methods so its installation includes special procedures for creating a shared object file.
HdfeosDefault has the constructor:
public HdfeosDefault();An HdfeosDefault instance can open any number of HDF-EOS files.
The VisAD HDF-EOS file adapter is dependent on software that must be obtained from NASA and NCSA. Specifically, users must obtain and install HDF4.1r1 from:
ftp://ftp.ncsa.uiuc.edu/HDF/HDF_Currentthen obtain and install HDF-EOS:
http://ulabibm.gsfc.nasa.gov/hdfeos/hdf.html#4See the visad/data/hdfeos/README.hdfeos file for installation instructions.
((ImageElement, ImageLine) -> (Red, Green, Blue))GIFForm has the constructor:
public GIFForm();A GIFForm instance can open any number of GIF and JPEG files.
Vis5DForm has the constructor:
public Vis5DForm();A Vis5DForm instance can open any number of Vis5D files.
AreaForm has the constructor:
public AreaForm();An AreaForm instance can open any number of McIDAS area files.
VisADForm has the constructor:
public VisADForm();A VisADForm instance can open any number of VisAD files.
Note that the main method of VisADForm can be used to convert any VisAD- readable file to a VisAD file. The command:
java -mx64m visad.data.visad.VisADForm in_file out_file.vadwill read in_file in any VisAD-readable format and convert it to a VisAD file in out_file.vad (note that ".vad" is the standard file name extension for VisAD files).
Note that VisAD classes do not yet implement version IDs and that VisAD class implementations are still changing. Thus serialized VisAD DataImpl objects are not appropriate for long term data storage.
The HDF-5 file adapter invokes native methods so its installation includes special procedures for installing a native library file.
HDF-5 has the constructor:
public HDF5Form();An HDF5Form instance can open any number of HDF-5 files.
The VisAD HDF-5 fila adapter is dependent on software that must be obtained from NCSA. See the VisAD README file for installation instructions.
Thus VisAD is designed to support a wide variety of user interfaces that present choices in terms that are familiar to users. Our specific plans for user interface experiments include:
http://www.ncsa.uiuc.edu/SDG/Software/Habanero/The visad.util package includes classes for needed user interface components that are not included in JFC, and for extensions of JFC classes that include connections to VisAD objects.
Several VisADSliders on different JVMs may be connected to the same RemoteDataReference to create a collaborative user interface slider.
/** JSlider values range between low and hi (with initial value
start) and are multiplied by scale to create Real values
of type referenced by ref */
public VisADSlider(String name, int low, int hi, int start,
double scale, DataReference ref, RealType type)
throws VisADException, RemoteException;
Users control LabeledRGBWidget and LabeledRGBAWidget pseudo color tables using the mouse. Click the left mouse button in the top part of the widget and drag to redraw the either the red, green, blue or alpha color graph. Click the center or right button to switch between red, green, blue and alpha graphs. Click the left mouse button in the bottom part of the widget and drag the arrow to see which RealType values are associated with the colors in the color bar.
/** this will be labeled with the name of map's RealType;
the range of RealType values mapped to color is taken from
map.getRange() - this allows a color widget to be used with
a range of values defined by auto-scaling from displayed Data;
if map's range values are not available at the time this
constructor is invoked, the LabeledRGBWidget becomes a
ScalarMapListener and sets its range when map's range is set;
the DisplayRealType of map must be Display.RGB and should
already be added to a Display */
public LabeledRGBWidget(ScalarMap map)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values (min, max) is mapped to color
as defined by an interactive color widget;
the DisplayRealType of map must be Display.RGB and should
already be added to a Display */
public LabeledRGBWidget(ScalarMap map, float min, float max)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values (min, max) is mapped to color
as defined by an interactive color widget; table initializes
the color lookup table, organized as float[TABLE_SIZE][3]
with values between 0.0f and 1.0f;
the DisplayRealType of map must be Display.RGB and should
already be added to a Display */
public LabeledRGBWidget(ScalarMap map, float min, float max,
float[][] table)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values mapped to color is taken from
map.getRange() - this allows a color widget to be used with
a range of values defined by auto-scaling from displayed Data;
if map's range values are not available at the time this
constructor is invoked, the LabeledRGBAWidget becomes a
ScalarMapListener and sets its range when map's range is set;
the DisplayRealType of map must be Display.RGBA and should
already be added to a Display */
public LabeledRGBAWidget(ScalarMap map)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values (min, max) is mapped to color
as defined by an interactive color widget;
the DisplayRealType of map must be Display.RGBA and should
already be added to a Display */
public LabeledRGBAWidget(ScalarMap map, float min, float max)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values (min, max) is mapped to color
as defined by an interactive color widget; table initializes
the color lookup table, organized as float[TABLE_SIZE][4]
with values between 0.0f and 1.0f;
the DisplayRealType of map must be Display.RGBA and should
already be added to a Display */
public LabeledRGBAWidget(ScalarMap map, float min, float max,
float[][] table)
throws VisADException, RemoteException;
/** set maximum size of widget using java.awt.Dimension */ public setMaximumSize(Dimension d);
Users control the SelectRangeWidget range using the mouse. Change either end of the range by dragging with the mouse. Click in the middle of the range to move both ends of the range in unison.
/** this will be labeled with the name of map's RealType;
the range of RealType values defining the bounds of the
selectable range is taken from map.getRange() - this allows
a SelectRangeWidget to be used with a range of values defined
by auto-scaling from displayed Data; if map's range values
are not available at the time this constructor is invoked,
the SelectRangeWidget becomes a ScalarMapListener and sets
its range when map's range is set;
the DisplayRealType of map must be Display.SelectRange and
should already be added to a Display */
public SelectRangeWidget(ScalarMap map)
throws VisADException, RemoteException;
/** this will be labeled with the name of map's RealType;
the range of RealType values (min, max) is defines the
bounds of the selectable range;
the DisplayRealType of map must be Display.SelectRange and
should already be added to a Display */
public SelectRangeWidget(ScalarMap map, float min, float max)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.Animation and
should already be added to a Display */
public AnimationWidget(ScalarMap map)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.Animation and
should already be added to a Display; st is the dwell time
per animation step, in milliseconds */
public AnimationWidget(ScalarMap map, int st)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.IsoContour and
should already be added to a Display */
public ContourWidget(ScalarMap map)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.IsoContour and
should already be added to a Display; surf is an initial
iso-surface value */
public ContourWidget(ScalarMap map, float surf)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.IsoContour and
should already be added to a Display; initial iso-lines are
generated for values in an arithmetic progression centered at
base with in increment of interval, between min and max */
public ContourWidget(ScalarMap map, float interval, float min,
float max, float base)
throws VisADException, RemoteException;
/** the DisplayRealType of map must be Display.IsoContour and
should already be added to a Display; initial iso-lines are
generated for values in an arithmetic progression centered at
base with in increment of interval, between min and max; surf
is an initial iso-surface value; if update is true, then the
range of legals min and max values is updated whenever the
range of data values in map is auto-scaled */
public ContourWidget(ScalarMap map, float interval, float min,
float max, float base, float surf,
boolean update)
throws VisADException, RemoteException;
/** create a GMCWidget for control */ public GMCWidget(GraphicsModeControl control);
The simplest way to use VisAD is through its Spread Sheet, which is described in Section 10 and provides a way to use VisAD without any user programming at all. It enables users to read a variety of file formats, display their contents, change the way they are displayed, and perform simple arithmetic operations on them (e.g., subtract two images and display the result).
The visad.util.DataUtility class provides the simplest level of support for users who need to write their own programs. For example, if you have a program that computes some image pixel brightnesses and want to display them, you can use the static makeImage and makeSimpleDisplay methods of DataUtility to do that in just a couple lines of code. Given an array of pixel brightnesses:
float pixels[nlines][nelements]the following code creates a VisAD image and displays it:
FlatField image = DataUtility.makeImage(pixels);
DisplayImpl display = DataUtility.makeSimpleDisplay(image);
JFrame jframe = new JFrame("simple image display");
jframe.setContentPane(((JPanel) display.getComponent());
jframe.pack();
jframe.setVisible(true);
Only the first two lines of code have to do with VisAD: the first creates the
data object (with class FlatField) and the second displays it. The other four
lines of code set up a minimal Java frame for the display. The
makeSimpleDisplay method of DataUtility can create a simple display for almost
any VisAD data object. We will add more methods to DataUtility similar to
makeImage, to construct other simple kinds of data objects, like 2-D and 3-D
grids, and tables.The visad.MathType class provides some useful methods for users who need to explicitly construct and manipulate MathTypes for more complex data objects. Its stringToType method enables users to construct complex MathTypes from the shorthand notation described in Section 3.1. Recall that the shorthand MathType for multi-spectral satellite image of Earth is:
( (latitude, longitude) ->
(radiance_channel_1, ..., radiance_channel_N) )
The shorthand MathType for the output of a weather model is:
( time -> ( (latitude, longitude, altitude) ->
(temperature, pressure, dewpoint, wind_u, wind_v, wind_w) ) )
And the shorthand MathType for a set of map boundaries is:
set ( (latitude, longitude) )The static stringToType method of MathType takes a String argument, which is assumed to be in this shorthand notation, and returns the corresponding MathType (of course, MathTypes returned by stringToType do not include any non-null default Units, CoordinateSystems or Sets). The prettyString method of MathType returns a String with this shorthand notation for any VisAD MathType.
The guessMaps method of MathType returns an array of ScalarMaps appropriate for displaying data objects with this MathType. The guessMaps method has one argument, a boolean threeD, which is true if a 3-D display is OK.
For up-to-date information about the VisAD Spread Sheet, see the VisAD Spread Sheet web page at http://www.ssec.wisc.edu/~curtis/ss.html (this is linked to the main VisAD web page at http://www.ssec.wisc.edu/~billh/visad.html).
------------------------------------------------------------------------------- Note: You must have the HDF-EOS and HDF-5 file adapter native C code compiled in order to import data sets of those types. See the VisAD README file for information on how to compile this native code. -------------------------------------------------------------------------------
------------------------------------------------------------------------------- WARNING: Exporting a cell as serialized data is a handy and portable way to store data, but each time the VisAD Data class hierarchy changes, old serialized data files become obsolete and will no longer load properly. For long term storage of your data, use the "Export data to netCDF" or “Export data to HDF-5” command. -------------------------------------------------------------------------------
Any of the following can be used in formula construction:
d(DATA)/d(TYPE)
where DATA is a Function, and TYPE is the name of a RealType present in the
Function's domain. This syntax calls Function's derivative() method with an
error_type of Data.NO_ERRORS.
DATA1(DATA2)
where DATA1 is a Function and DATA2 is a Real or a RealTuple. This syntax calls
Function's evaluate() method.
DATA(N)
where DATA is the Field, and N is a literal integer. Use DATA(0) for the first
sample of DATA. This syntax calls Field's getSample() method.
DATA.N
where DATA is a Tuple and N is a literal integer. Use DATA.0 for the first
Tuple component of DATA. This syntax calls Tuple's getComponent() method.
EXTRACT(DATA, N)
where DATA is a Field and N is a literal integer. This syntax calls Field's
extract() method.
SQRT(A2 + B2^5 - MIN(B1, -C1))
d(A2 + B2)/d(ImageElement)
A2(A3)
C2.6
(B1 * C1)(A3).1
Once you've typed in a formula, press Enter or click the green check box button
to the left of the formula entry text box to apply the formula. The red X
button will cancel your entry, restoring the formula to its previous state. The
open folder button to the right of the formula entry text box is a shortcut to
the File menu's Import Data menu item.
link(package.Class.Method(DATA1, DATA2, ..., DATAn))
where package.Class.Method is the fully qualified method name and DATA1 through
DATAn are each Data objects or RealType objects.Keep the following points in mind when writing an external Java method that you wish to link to the SpreadSheet:
public static Data max(Data[] d)
that is part of a class called Util could be linked into a SpreadSheet cell with
any number of arguments; e.g.,
link(Util.max(A1, A2))
link(Util.max(A2, C3, B1, A1))
would both be correct references to the max method.
sqrt(A2 + B2^5 - min(B1, -C1))
d(A2 + B2)/d(ImageElement)
A2(A3)
C2.6[0]
(B1 * C1)(A3).1
C2 - 5*link(com.happyjava.vis.Linked.crunch(A6, C3, B5))
link(visad.Tuple.makeTuple(A2, A3, A4))
java -mx64m visad.ss.SpreadSheet -server name
where "name" is the desired name for the RMI server. If the server is created
successfully, the title bar will contain the server name in parentheses.Once your SpreadSheet is operating as an RMI server, other SpreadSheets can work with it collaboratively.
rmi://rmi.address/name/data
where "rmi.address" is the IP address of the RMI server, "name" is the name of
the RMI server, and "data" is the name of the data object desired.For example, suppose that the machine at address www.ssec.wisc.edu is running an RMI server called "VisADServ" using a SpreadSheet with two cells, A1 and B1. A SpreadSheet on another machine could import data from cell B1 of VisADServ by typing the following RMI address in the formula bar:
rmi://www.ssec.wisc.edu/VisADServ/B1
Just like file names, URLs, and formulas, the SpreadSheet will load the data,
showing the data box if the import is successful, or displaying error messages
within the cell if there is a problem.
java -mx64m visad.ss.SpreadSheet -client rmi.address/name
Where "rmi.address" is the IP address of the RMI server and "name" is the RMI
server's name. The resulting SpreadSheet will have the same cell layout as the
SpreadSheet RMI server and the same data with the same mappings. In addition,
it will be linked so that any changes to the SpreadSheet will be propagated to
the server and all its clones.Note that if a SpreadSheet RMI server does not support Java3D, none of its clones will be able to either. Thus, for maximum functionality, it is best to make sure that the machine chosen to be the RMI server supports Java3D.
java DisplayTest
// define an rgb color space
// (not to be confused with system's RGB DisplayTupleType)
RealType red = new RealType("red", null, null);
RealType green = new RealType("green", null, null);
RealType blue = new RealType("blue", null, null);
RealTupleType rgb = new RealTupleType(red, green, blue);
// define an hsv color space
// (not to be confused with system's HSV DisplayTupleType)
RealType hue = new RealType("hue", CommonUnit.degree, null);
RealType saturation = new RealType("saturation", null, null);
RealType value = new RealType("value", null, null);
// define the relation between the hsv and rgb color spaces
// using the same HSVCoordinateSystem that the system uses to
// define the relation between its RGB and HSV color spaces
CoordinateSystem hsv_system = new HSVCoordinateSystem(rgb);
RealTupleType hsv = new RealTupleType(hue, saturation, value,
hsv_system, null);
// construct a sampling of the hsv color space;
// since hue is composed of six linear (in rgb) pieces with
// discontinuous derivative bwteen pieces, it should be sampled
// at 6*n+1 points with n not too small;
// for a given hue, saturation and value are both linear in rgb
// so 2 samples suffice for each of them;
// the HSV - RGB transform is degenerate at satruration = 0.0
// and value = 0.0 so avoid those values;
// hue is in Units of degrees so that must be used in the Set
// constructor
Linear3DSet cube_set =
new Linear3DSet(hsv, 0.0, 360.0, 37,
0.01, 1.0, 2,
0.01, 1.0, 2, null,
new Unit[] {CommonUnit.degree, null, null},
null);
// construct a DataReference to cube_set so it can be displayed
DataReference cube_ref = new DataReferenceImpl("cube");
cube_ref.setData(cube);
// skip some code to set up UI . . .
// construct a Display
DisplayImplJ3D display1 = new DisplayImplJ3D("display1");
// map rgb to the Display spatial coordinates;
// note that red, green and blue do not occur in cube_set
// but are related to hue, saturation and reference via a
// CoordinateSystem that will be applied implicitly by
// Display logic
display1.addMap(new ScalarMap(red, Display.XAxis));
display1.addMap(new ScalarMap(green, Display.YAxis));
display1.addMap(new ScalarMap(blue, Display.ZAxis));
// define colors for points in hsv space
display1.addMap(new ScalarMap(hue, Display.Hue));
display1.addMap(new ScalarMap(saturation, Display.Saturation));
display1.addMap(new ScalarMap(value, Display.Value));
// construct mappings for interactive iso-surfaces of
// hue, saturation and value;
// the ContourControls must be extracted from these ScalarMaps
// to support interactive control of iso-surface levels
ScalarMap maphcontour = new ScalarMap(hue, Display.IsoContour);
display1.addMap(maphcontour);
ContourControl controlhcontour =
(ContourControl) maphcontour.getControl();
ScalarMap mapscontour = new ScalarMap(saturation, Display.IsoContour);
display1.addMap(mapscontour);
ContourControl controlscontour =
(ContourControl) mapscontour.getControl();
ScalarMap mapvcontour = new ScalarMap(value, Display.IsoContour);
display1.addMap(mapvcontour);
ContourControl controlvcontour =
(ContourControl) mapvcontour.getControl();
// display cube_set;
// it will be dispayed as a set of colored, interactive hue,
// saturation and value iso-surfaces, transformed into rgb space
display1.addReference(cube_ref);
The HSVCoordinateSystem class is used internally by the system for Displays
that include ScalarMaps to Display.Hue, Display.Saturation, Display.Value or
Display.HSV. Internally, it always has Reference Display.DisplayRGBTuple.
However, the HSVDisplay application constructs a HSVCoordinateSystem whose
Reference it maps to Display spatial axes in order to spatially visualize the
geometry of the relation between HSV and RGB color spaces.The GoesCollaboration application is part of the visad.paoloa package. Its source code, data files and installation instructions are available from the VisAD web page at:
http://www.ssec.wisc.edu/~billh/visad.htmlOnce the GoesCollaboration application is running on one machine, it may be started on other machines and connected to the first. This is specified by typing the IP name of the first machine as the command line argument of GoesCollaboration on other machines. For example, we could start the first (server) copy of GoesCollaboration on sparc.ssec.wisc.edu by typing the commands:
rmiregistry & java visad.paoloa.GoesCollaborationThen we could start GoesCollaboration (client) on any number of other machines by typing:
java visad.paoloa.GoesCollaboration sparc.ssec.wisc.eduThese copies of GoesCollaboration will all be connected together so that when the user drags sliders or re-draws atmospheric profiles in one copy of GoesCollaboration, all the users will see these changes and their computational consequences in their copies of GoesCollaboration.
The complete and annotated source code for the GoesCollaboration application is listed in Appendix B. Note that GoesCollaboration initially determines whether it is started as a server (with no argument) or as a client (with the IP name of the server as an argument). As a server it constructs a set of Data and DataReference objects which it serves via a RemoteServerImpl object bound to a URL. It also constructs sets of Cell, Display and VisADJSlider (user interface) objects connected to the DataReference objects. As a client it obtains references to RemoteDataReference objects from the server, then constructs Display and VisADJSlider objects which it connects to the RemoteDataReference objects from the server.
The GoesCollaboration application includes Fortran implementations of its science algorithms, which are invoked via JNI through C wrappers. These are only invoked by the applications computational Cells, and hence are only invoked by the server copy of GoesCollaboration. It is possible to run client copies of GoesCollaboration on machines that cannot run the Fortran science algorithms.
The ShallowFluid application is part of the visad.aune package. Its source code, data files and installation instructions are available from the VisAD web page at:
http://www.ssec.wisc.edu/~billh/visad.html
http://allegro.ssec.wisc.edu/jmet/
ftp://ftp.ssec.wisc.edu/pub/visad-2.0/images.nc.ZTo run this application, change to the visad/examples directory and enter the command:
java SimpleAnimate (step_time_in_ms)where (step_time_in_ms) is an optional parameter giving the animation step time in milliseconds. The default value is 1000 ms.
ftp://ftp.ssec.wisc.edu/pub/visad-2.0/lowresTerrain.ncTo run this application, change to the visad/examples directory and enter the command:
java -Xmx64m Earth lowresTerrain.nc
However, for the initial release of VisAD, ubiquity and performance are problems. As described in Section 3.9, VisAD makes few method calls, so that its speed should be good once compilers are able to get good speed on loops over arrays of floats and doubles. Memory performance is also a problem with the current release of Java3D, which is used by VisAD. This should be improved in version 1.2 of Java3D. Note that VisAD Data objects can be stored efficiently with appropriate choices of range Sets in FlatField constructors, although many file adapters just store all input values as (4-byte) floats. If VisAD throws an OutOfMemoryException, increase memory size of the Java interpreter with the - mx command line option.
The AuditTrail class is not implemented in the initial release of VisAD. Display logic is unimplemented for some combinations of ScalarMaps and MathTypes. The ErrorEstimate, ProductSet and UnionSet classes are not well tested. The file format adapters may fail to adapt some files, and may not adapt all information in other files.
The initial release of VisAD was essentially simultaneous with the public early access release of Java3D. Java 2 (aka JDK 1.2) is are required for VisAD. Either Java2D (included in Java 2) or Java3D can be used for displays. Most vendors have Java 2 alpha releases as of May 1999.
We will continue to add file format adapters and associated metadata classes such as new CoordinateSystems and Sets. We will develop packages for statistics and mathematical analysis operations. We will add more support for collaborative user interfaces, and will develop a number of generic user interfaces such as a general spread sheet.
We will try to support developers using VisAD, by fixing bugs, answering questions and adding requested features. VisAD's extensibility should enable developers to add new features to the system.
http://www.ssec.wisc.edu/~billh/visad.htmlYou can get help with problems from the VisAD mailing list at:
visad-list@ssec.wisc.eduYou can join the VisAD mailing list by sending an email message to:
majordomo@ssec.wisc.eduthat includes the line:
subscribe visad-listin the body of the message (not the subject line). If you get an Exception in a VisAD class that you need our help with, it will be very useful if you paste the text of the stack trace from the Exception into your email message. In many cases, Exceptions from VisAD will tell you that you have passed illegal arguments to a method of a VisAD class. Hopefully in such cases our Exception messages will help you find errors in your application.
If you are interested in collaborating with us on VisAD developments please send email to Bill Hibbard at hibbard@facstaff.wisc.edu.
2. Beshers, C., and S. Feiner, 1992; Automated design of virtual worlds for visualizing multivariate relations. Proc. Visualization '92, IEEE. 283-290.
3. Haber, R. B., B. Lucas and N. Collins, 1991; A data model for scientific visualization with provisions for regular and irregular grids. Proc. Visualization 91. IEEE. 298-305.
4. Hasler, A. F., J. Dodge, and R. H. Woodward, 1991; A High Performance Interactive Image Spreadsheet. Preprints of the Seventh International Conference on Interactive Information and Processing systems for Meteorology, Oceanography and Hydrology, New Orleans, Amer. Meteor. Soc., 187-194.
5. Hibbard, W., 1986; 4-D display of meteorological data. Proceedings, 1986 Workshop on Interactive 3D Graphics. Chapel Hill, ACM Siggraph, 23-36.
6. Hibbard, W., and D. Santek, 1990; The Vis5D system for easy interactive visualization. Proc. Visualization '90, San Francisco, IEEE. 28-35.
7. Hibbard, W., D. Santek, and G. Tripoli, 1991; Interactive atmospheric data access via high speed networks. Computer Networks and ISDN Systems, 22, 103- 109.
8. Hibbard, W., C. Dyer and B. Paul, 1992; Display of scientific data structures for algorithm visualization. Proc. Visualization '92, Boston, IEEE, 139-146.
9. Hibbard, W. L., B. E. Paul, D. A. Santek, C. R. Dyer, A. L. Battaiola, and M- F. Voidrot-Martinez, 1994; Interactive visualization of Earth and space science computations. IEEE Computer 27(7), 65-72.
10.Hibbard, W, J. Anderson, I. Foster, B. Paul, R. Jacob, C. Schafer, and M. Tyree, 1996; Exploring Coupled Atmosphere-Ocean Models Using Vis5D. Int. J. of Supercomputer Applications, 10(2), 211-222.
A TupleType is flat if all its components are RealTypes or RealTupleTypes. A FunctionType is flat if its range is a RealType or a flat TupleType (note that a flat FunctionType is appropriate for the MathType of a FlatField).
The MathType of each displayed Data object defines a tree structure whose leaves are RealTypes (TextTypes are ignored). We define terminal nodes as nodes in this tree that are:
// // GoesCollaboration.java // package visad.paoloa; // VisAD packages import visad.*; import visad.util.Delay; import visad.util.VisADSlider; import visad.java3d.DisplayImplJ3D; import visad.java3d.TwoDDisplayRendererJ3D; import visad.java3d.DirectManipulationRendererJ3D; // Java packages import java.io.File; import java.rmi.RemoteException; import java.rmi.NotBoundException; import java.rmi.AccessException; import java.rmi.Naming; import java.net.MalformedURLException; // JFC packages import javax.swing.*; import javax.swing.event.*; import javax.swing.text.*; import javax.swing.border.*; // AWT packages import java.awt.*; import java.awt.event.*; /** GoesCollaboration implements the interactive and collaborative Goes satellite sounding retrieval application using VisAD 2.0. It is rewritten from the IRGS.v application developed for VisAD 1.1 by Paolo Antonelli.*/ public class GoesCollaboration extends Object { /** RemoteServerImpl for server this GoesCollaboration is a server if server_server != null */ RemoteServerImpl server_server; /** RemoteServer for client this GoesCollaboration is a client if client_server != null */ RemoteServer client_server; /** declare MathTypes */ RealType nchan; RealType indx; RealType nl; RealType tbc; RealType tbc_d; RealType wfn; RealType pres; RealType temp; RealType mixr; RealType ozone; RealType pressure; RealType data_real; RealType diff; /** declare DataReferences */ DataReference wfna_ref; DataReference tempa_ref; DataReference mixra_ref; DataReference ozonea_ref; DataReference presa_ref; DataReference diff_col_ref; DataReference diff_ref; DataReference zero_line_ref; DataReference smr_ref; DataReference real_tbc_ref; DataReference wfnb_ref; DataReference wfna_old_ref; /** slider DataReferences */ DataReference gzen_ref; DataReference tskin_ref; DataReference in_dx_ref; /** the width and height of the UI frame */ public static int WIDTH = 1200; public static int HEIGHT = 1000; /** type 'java visad.paoloa.GoesCollaboration' to run this application; the main thread just exits, since Display, Cell and JFC threads run the application */ public static void main(String args[]) throws VisADException, RemoteException { // construct GoesCollaboration application GoesCollaboration goes = new GoesCollaboration(args); if (goes.client_server != null) { goes.setupClient(); } else if (goes.server_server != null) { // load native method library (only needed for server) System.loadLibrary("GoesCollaboration"); goes.setupServer(); } else { // stand-alone (neither client nor server) // load native method library System.loadLibrary("GoesCollaboration"); goes.setupServer(); } } /** Construct the GoesCollaboration application, including Data objects, Display objects, Cell (computational) objects, and JFC (slider) user interface objects. The Display, Cell and JFC objects include threads and links to Data objects (via DataReference objects). Display and Cell threads wake up when linked Data objects change. Display and JFC objects wake up on mouse events. Display, Cell and JFC objects cause changes to Data objects. Here's a summary of the event logic among Data, Displays, Cells, and JSliders: initialization -> zero_line = 0 -> display4 slider <--gt; in_dx slider <--> gzen slider <--> tskin slider <--> save_config in_dx -> real_tbcCell real_tbc = re_read_1_c(in_dx) month = 6 lat = real_tbc[18]; (tempa, mixra, ozonea, presa) = get_profil_c(lat, month) -> display2 direct_manipualtion (in display2) -> (tempa, mixra, ozonea) -> display2 gzen, tskin, tempa, mixra, ozonea, presa -> wfnbCell wfnb = goesrte_2_c(gzen, tskin, tempa, mixra, ozonea, presa) wfnb, real_tbc -> wfnaCell wfna = wfnb.wfn -> display1 diff_DATA = wfnb.tbc[nl=1] - real_tbc -> display4 smr = RootMeanSquare(diff_DATA) -> display4 save_config -> wfna_oldCell wfna_old = wfna wfna, wfna_old -> diff_colCell diff_col = wfna - wfna_old -> display3 */ public GoesCollaboration(String args[]) throws VisADException, RemoteException { if (args.length > 0) { // this is a client // try to connect to RemoteServer String domain = "//" + args[0] + "/GoesCollaboration"; try { client_server = (RemoteServer) Naming.lookup(domain); } catch (MalformedURLException e) { System.out.println("Cannot connect to server"); System.exit(0); } catch (NotBoundException e) { System.out.println("Cannot connect to server"); System.exit(0); } catch (AccessException e) { System.out.println("Cannot connect to server"); System.exit(0); } catch (RemoteException e) { System.out.println("Cannot connect to server"); System.exit(0); } } else { // args.length == 0 // this is a server /* CTR: 30 Sep 1998 */ // check for the existence of necessary data files { File f1 = new File("data_obs_1.dat"); File f2 = new File("goesrtcf"); if (!f1.exists() || !f2.exists()) { System.out.println("This program requires the data files " + "\"data_obs_1.dat\""); System.out.println("and \"goesrtcf\", available at:"); System.out.println(" ftp://ftp.ssec.wisc.edu/pub/visad-2.0/" + "paoloa-files.tar.Z"); System.exit(1); } if (!f2.exists()) { System.out.println(""); System.exit(2); } } // try to set up a RemoteServer server_server = new RemoteServerImpl(); try { Naming.rebind("//:/GoesCollaboration", server_server); } catch (MalformedURLException e) { System.out.println("Cannot set up server - running as stand-alone"); server_server = null; } catch (AccessException e) { System.out.println("Cannot set up server - running as stand-alone"); server_server = null; } catch (RemoteException e) { System.out.println("Cannot set up server - running as stand-alone"); server_server = null; } } } /** set up as server */ void setupServer() throws VisADException, RemoteException { // // construct function domain sampling Sets // // construct 1-D Sets Set linear18 = new Linear1DSet(1.0, 18.0, 18); Set linear19 = new Linear1DSet(1.0, 19.0, 19); Set linear40 = new Linear1DSet(1.0, 40.0, 40); // construct 2-D Set Set linear40x18 = new Linear2DSet(1.0, 40.0, 40, 1.0, 18.0, 18); // // construct MathTypes for Data objects // // construct RealTypes used as Function domains // with null Units but non-null default Sets (for // function domain samplings) nchan = new RealType("nchan", null, linear18); indx = new RealType("indx", null, linear19); nl = new RealType("nl", null, linear40); // construct RealTypes used as Function ranges // or for simple Real values, with null Units // and null default Sets tbc = new RealType("tbc", null, null); tbc_d = new RealType("tbc_d", null, null); wfn = new RealType("wfn", null, null); pres = new RealType("pres", null, null); temp = new RealType("temp", null, null); mixr = new RealType("mixr", null, null); ozone = new RealType("ozone", null, null); pressure = new RealType("pressure", null, null); data_real = new RealType("data_real", null, null); diff = new RealType("diff", null, null); // construct RealTupleType used as a Function domain // with non-null default Set RealTupleType nl_nchan = new RealTupleType(nl, nchan, null, linear40x18); // construct FunctionTypes FunctionType obs_data = new FunctionType(indx, data_real); FunctionType wfn_big = new FunctionType(nl_nchan, new RealTupleType(wfn, tbc)); FunctionType tbc_array_dif = new FunctionType(nchan, tbc_d); FunctionType wfn_array = new FunctionType(nl_nchan, wfn); FunctionType temp_array = new FunctionType(nl, temp); FunctionType mixr_array = new FunctionType(nl, mixr); FunctionType ozone_array = new FunctionType(nl, ozone); FunctionType pres_array = new FunctionType(nl, pressure); // // construct Data objects and DataReferences to them // // construct weighting function Data object and DataReference FlatField wfna = new FlatField(wfn_array); wfna_ref = new DataReferenceImpl("wfna"); wfna_ref.setData(wfna); // construct temperature profile Data object and DataReference FlatField tempa = new FlatField(temp_array); tempa_ref = new DataReferenceImpl("tempa"); tempa_ref.setData(tempa); // construct mixing ratio profile Data object and DataReference FlatField mixra = new FlatField(mixr_array); mixra_ref = new DataReferenceImpl("mixra"); mixra_ref.setData(mixra); // construct ozone profile Data object and DataReference FlatField ozonea = new FlatField(ozone_array); ozonea_ref = new DataReferenceImpl("ozonea"); ozonea_ref.setData(ozonea); // construct pressure profile Data object and DataReference FlatField presa = new FlatField(pres_array); presa_ref = new DataReferenceImpl("presa"); presa_ref.setData(presa); // construct weighting function difference Data object // and DataReference FlatField diff_col = new FlatField(wfn_array); diff_col_ref = new DataReferenceImpl("diff_col"); diff_col_ref.setData(diff_col); // construct brightness temperature error Data object // and DataReference FlatField diff_DATA = new FlatField(tbc_array_dif); diff_ref = new DataReferenceImpl("diff"); diff_ref.setData(diff_DATA); // construct zero line Data object and DataReference FlatField zero_line = new FlatField(tbc_array_dif); zero_line_ref = new DataReferenceImpl("zero_line"); zero_line_ref.setData(zero_line); // construct brightness temperature error root mean square // Data object and DataReference Real smr = new Real(tbc_d); smr_ref = new DataReferenceImpl("smr"); smr_ref.setData(smr); // construct observed brightness temperature Data object // and DataReference FlatField real_tbc = new FlatField(obs_data); real_tbc_ref = new DataReferenceImpl("real_tbc"); real_tbc_ref.setData(real_tbc); // construct compound weighting function Data object // and DataReference FlatField wfnb = new FlatField(wfn_big); wfnb_ref = new DataReferenceImpl("wfnb"); wfnb_ref.setData(wfnb); // construct saved weighting function Data object // and DataReference FlatField wfna_old = new FlatField(wfn_array); wfna_old_ref = new DataReferenceImpl("wfna_old"); wfna_old_ref.setData(wfna); // // construct DataReference objects linked to VisADSliders (the // JSlider constructors will construct Real data objects for // these, so there is no point in constructing Real data objects // here) // // DataReference for zenith angle gzen_ref = new DataReferenceImpl("gzen"); // DataReference for skin temperature tskin_ref = new DataReferenceImpl("tskin"); // DataReference for index into model atmospheres in_dx_ref = new DataReferenceImpl("in_dx"); // DataReference used to trigger copying wfna to wfna_old DataReference save_config_ref = new DataReferenceImpl("save_config"); // set up Displays for server DisplayImpl[] displays = new DisplayImpl[4]; setupDisplays(displays); if (server_server != null) { for (int i = 0; i < displays.length; i++) { server_server.addDisplay(new RemoteDisplayImpl(displays[i])); } } // set up user interface setupUI(displays, in_dx_ref, save_config_ref, gzen_ref, tskin_ref); // initialize zero reference line for brightness temperature errors double[][] zero_line_x = zero_line.getValues(); for (int i=0; i<zero_line_x[0].length; i++) zero_line_x[0][i] = 0.0; zero_line.setSamples(zero_line_x); // make sure Data are initialized new Delay(1000); gzen_ref.incTick(); save_config_ref.incTick(); new Delay(1000); // // construct computational Cells and links to DataReferences // that trigger them // // construct a real_tbcCell real_tbcCell real_tbc_cell = new real_tbcCell(); real_tbc_cell.addReference(in_dx_ref); new Delay(500); // construct a wfnbCell wfnbCell wfnb_cell = new wfnbCell(); wfnb_cell.addReference(gzen_ref); wfnb_cell.addReference(tskin_ref); wfnb_cell.addReference(tempa_ref); wfnb_cell.addReference(mixra_ref); wfnb_cell.addReference(ozonea_ref); wfnb_cell.addReference(presa_ref); new Delay(500); // construct a wfnaCell wfnaCell wfna_cell = new wfnaCell(); wfna_cell.addReference(wfnb_ref); wfna_cell.addReference(real_tbc_ref); new Delay(500); // construct a wfna_oldCell wfna_oldCell wfna_old_cell = new wfna_oldCell(); wfna_old_cell.addReference(save_config_ref); new Delay(500); // construct a diff_colCell diff_colCell diff_col_cell = new diff_colCell(); diff_col_cell.addReference(wfna_ref); diff_col_cell.addReference(wfna_old_ref); new Delay(500); if (server_server != null) { // set RemoteDataReferenceImpls in RemoteServer RemoteDataReferenceImpl[] refs = new RemoteDataReferenceImpl[4]; refs[0] = new RemoteDataReferenceImpl((DataReferenceImpl) gzen_ref); refs[1] = new RemoteDataReferenceImpl((DataReferenceImpl) tskin_ref); refs[2] = new RemoteDataReferenceImpl((DataReferenceImpl) in_dx_ref); refs[3] = new RemoteDataReferenceImpl((DataReferenceImpl) save_config_ref); server_server.setDataReferences(refs); } // make sure Data are initialized (again) new Delay(1000); gzen_ref.incTick(); save_config_ref.incTick(); } /** set up as client */ void setupClient() throws VisADException, RemoteException { // // get RemoteDataReferences // RemoteDataReference[] refs = client_server.getDataReferences(); if (refs == null) { System.out.println("Cannot connect to server"); System.exit(0); } gzen_ref = refs[0]; tskin_ref = refs[1]; in_dx_ref = refs[2]; DataReference save_config_ref = refs[3]; // set up Displays for client DisplayImpl[] displays = new DisplayImpl[4]; displays[0] = new DisplayImplJ3D(client_server.getDisplay("display1")); displays[1] = new DisplayImplJ3D(client_server.getDisplay("display2")); displays[2] = new DisplayImplJ3D(client_server.getDisplay("display3")); displays[3] = new DisplayImplJ3D(client_server.getDisplay("display4")); // set up user interface setupUI(displays, in_dx_ref, save_config_ref, gzen_ref, tskin_ref); } /** set up Displays; return constructed Displays in displays array */ void setupDisplays(DisplayImpl[] displays) throws VisADException, RemoteException { // // construct Displays and link to Data objects // // construct Display 1 (using default DisplayRenderer); // the text name is used only for debugging DisplayImplJ3D display1 = new DisplayImplJ3D("display1"); // construct ScalarMaps for Display 1; // explicitly set data range for nl values (in order to // invert scale) ScalarMap map1nl = new ScalarMap(nl, Display.YAxis); map1nl.setRange(40.0, 1.0); display1.addMap(map1nl); // setRange is not invoked for other ScalarMaps - they will // use auto-scaling from actual data values display1.addMap(new ScalarMap(nchan, Display.XAxis)); display1.addMap(new ScalarMap(wfn, Display.Green)); display1.addMap(new ScalarMap(wfn, Display.ZAxis)); display1.addMap(new ConstantMap(0.5f, Display.Red)); display1.addMap(new ConstantMap(0.5f, Display.Blue)); GraphicsModeControl mode1 = display1.getGraphicsModeControl(); mode1.setScaleEnable(true); // link weighting function Data object to display1 // (using default DataRenderer and a null array of ConstantMaps) display1.addReference(wfna_ref); // construct Display 2 and its ScalarMaps (using non-default // 2-D DisplayRenderer) DisplayImplJ3D display2 = new DisplayImplJ3D("display2", new TwoDDisplayRendererJ3D()); // explicitly set data range for nl values (in order to // invert scale) ScalarMap map2nl = new ScalarMap(nl, Display.YAxis); map2nl.setRange(40.0, 1.0); display2.addMap(map2nl); // map temp, mixr and ozone to XAxis and // set axis scale colors ScalarMap map2temp = new ScalarMap(temp, Display.XAxis); display2.addMap(map2temp); map2temp.setScaleColor(new float[] {1.0f, 0.0f, 0.0f}); ScalarMap map2mixr = new ScalarMap(mixr, Display.XAxis); display2.addMap(map2mixr); map2mixr.setScaleColor(new float[] {0.0f, 1.0f, 0.0f}); ScalarMap map2ozone = new ScalarMap(ozone, Display.XAxis); display2.addMap(map2ozone); map2ozone.setScaleColor(new float[] {0.0f, 0.0f, 1.0f}); display2.addMap(new ScalarMap(pressure, Display.XAxis)); GraphicsModeControl mode2 = display2.getGraphicsModeControl(); mode2.setLineWidth(2.0f); mode2.setScaleEnable(true); // color temperature profile red ConstantMap[] tmaps = {new ConstantMap(1.0f, Display.Red), new ConstantMap(0.0f, Display.Green), new ConstantMap(0.0f, Display.Blue)}; // color mixing ratio profile green ConstantMap[] mmaps = {new ConstantMap(0.0f, Display.Red), new ConstantMap(1.0f, Display.Green), new ConstantMap(0.0f, Display.Blue)}; // color ozone profile blue ConstantMap[] omaps = {new ConstantMap(0.0f, Display.Red), new ConstantMap(0.0f, Display.Green), new ConstantMap(1.0f, Display.Blue)}; // color pressure profile white ConstantMap[] pmaps = {new ConstantMap(1.0f, Display.Red), new ConstantMap(1.0f, Display.Green), new ConstantMap(1.0f, Display.Blue)}; // enable direct manipulation for temperature, mixing ratio // and ozone profiles; do not enable direct manipulation for // pressure; // note that addReferences rather than addReference is // invoked for non-default DataRenderers (in this case, // DirectManipulationRendererJ3D); // note also that addReference and addReferences may take // an array of ConstantMaps that apply only to one Data // object display2.addReferences(new DirectManipulationRendererJ3D(), tempa_ref, tmaps); display2.addReferences(new DirectManipulationRendererJ3D(), mixra_ref, mmaps); display2.addReferences(new DirectManipulationRendererJ3D(), ozonea_ref, omaps); display2.addReference(presa_ref, pmaps); // construct Display 3 and its ScalarMaps DisplayImplJ3D display3 = new DisplayImplJ3D("display3"); // explicitly set data range for nl values (in order to // invert scale) ScalarMap map3nl = new ScalarMap(nl, Display.YAxis); map3nl.setRange(40.0, 1.0); display3.addMap(map3nl); display3.addMap(new ScalarMap(nchan, Display.XAxis)); display3.addMap(new ScalarMap(wfn, Display.ZAxis)); display3.addMap(new ScalarMap(wfn, Display.Green)); display3.addMap(new ConstantMap(0.5f, Display.Red)); display3.addMap(new ConstantMap(0.5f, Display.Blue)); GraphicsModeControl mode3 = display3.getGraphicsModeControl(); mode3.setScaleEnable(true); // link weighting function difference Data object to display3 display3.addReference(diff_col_ref); // construct Display 4 and its ScalarMaps (using non-default // 2-D DisplayRenderer) DisplayImplJ3D display4 = new DisplayImplJ3D("display4", new TwoDDisplayRendererJ3D()); display4.addMap(new ScalarMap(nchan, Display.XAxis)); // explicitly set data range for tbc_d values ScalarMap map4tbc_d = new ScalarMap(tbc_d, Display.YAxis); map4tbc_d.setRange(-40.0, 40.0); display4.addMap(map4tbc_d); // set pointSize = 5 in display4 to make single Real value smr // easily visible GraphicsModeControl mode4 = display4.getGraphicsModeControl(); mode4.setPointSize(5.0f); mode4.setLineWidth(2.0f); mode4.setScaleEnable(true); // link brightness temperature error, zero line and brightness // temperature error root mean square Data objects to display4 display4.addReference(diff_ref); display4.addReference(zero_line_ref); display4.addReference(smr_ref); // return DisplayImpls displays[0] = display1; displays[1] = display2; displays[2] = display3; displays[3] = display4; } /** construct user interface using JFC */ void setupUI(DisplayImpl[] displays, DataReference in_dx_ref, DataReference save_config_ref, DataReference gzen_ref, DataReference tskin_ref) throws VisADException, RemoteException { // // construct JFC user interface with JSliders linked to // Data objects, and embed Displays into JFC JFrame // // create a JFrame JFrame frame = new JFrame("GoesCollaboration"); WindowListener l = new WindowAdapter() { public void windowClosing(WindowEvent e) {System.exit(0);} }; frame.addWindowListener(l); frame.setSize(WIDTH, HEIGHT); frame.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR)); Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); frame.setLocation(screenSize.width/2 - WIDTH/2, screenSize.height/2 - HEIGHT/2); // create big_panel JPanel in frame JPanel big_panel = new JPanel(); big_panel.setLayout(new BoxLayout(big_panel, BoxLayout.X_AXIS)); big_panel.setAlignmentY(JPanel.TOP_ALIGNMENT); big_panel.setAlignmentX(JPanel.LEFT_ALIGNMENT); frame.getContentPane().add(big_panel); // create left hand side JPanel for sliders and text JPanel left = new JPanel(); // FlowLayout and double buffer left.setLayout(new BoxLayout(left, BoxLayout.Y_AXIS)); left.setAlignmentY(JPanel.TOP_ALIGNMENT); left.setAlignmentX(JPanel.LEFT_ALIGNMENT); big_panel.add(left); // construct JLabels // (JTextArea does not align in BoxLayout well, so use JLabels) left.add(new JLabel("Interactive GOES satellite sounding " + "retrieval")); left.add(new JLabel("using VisAD - see:")); left.add(new JLabel(" ")); left.add(new JLabel(" http://www.ssec.wisc.edu/~billh/visad.html")); left.add(new JLabel(" ")); left.add(new JLabel("for more information about VisAD.")); left.add(new JLabel(" ")); left.add(new JLabel("Bill Hibbard, Paolo Antonelli and Bob Aune")); left.add(new JLabel("Space Science and Engineering Center")); left.add(new JLabel("University of Wisconsin - Madison")); left.add(new JLabel(" ")); left.add(new JLabel(" ")); left.add(new JLabel("Move index slider to retrieve a new model")); left.add(new JLabel("atmosphere.")); left.add(new JLabel(" ")); left.add(new JLabel("Touch ref. conf. slider to save a new")); left.add(new JLabel("reference for weighting function " + "difference.")); left.add(new JLabel(" ")); left.add(new JLabel("Move zenith angle and skin T sliders to")); left.add(new JLabel("to modify atmosphere conditions.")); left.add(new JLabel(" ")); left.add(new JLabel("Rotate scenes with left mouse button.")); left.add(new JLabel(" ")); left.add(new JLabel("Redraw temperature, water vapor and ozone " + "with")); left.add(new JLabel("right mouse button to modify model " + "atmosphere.")); left.add(new JLabel(" ")); left.add(new JLabel(" ")); // create sliders JPanel JPanel sliders = new JPanel(); sliders.setName("GoesCollaboration Sliders"); sliders.setFont(new Font("Dialog", Font.PLAIN, 12)); sliders.setLayout(new BoxLayout(sliders, BoxLayout.Y_AXIS)); sliders.setAlignmentY(JPanel.TOP_ALIGNMENT); sliders.setAlignmentX(JPanel.LEFT_ALIGNMENT); left.add(sliders); // construct VisADSliders linked to Real Data objects and embedded // in sliders JPanel sliders.add(new VisADSlider("index", 1, 2234, 1, 1.0, in_dx_ref, RealType.Generic)); sliders.add(new JLabel(" ")); sliders.add(new VisADSlider("save as ref. conf.?", 0, 1000, 0, 1.0, save_config_ref, RealType.Generic)); sliders.add(new JLabel(" ")); sliders.add(new VisADSlider("zenith angle (deg)", 0, 65, 35, 1.0, gzen_ref, RealType.Generic)); sliders.add(new JLabel(" ")); sliders.add(new VisADSlider("skin T (K)", 250, 340, 300, 1.0, tskin_ref, RealType.Generic)); // construct JPanel and sub-panels for Displays JPanel display_panel = new JPanel(); display_panel.setLayout(new BoxLayout(display_panel, BoxLayout.X_AXIS)); display_panel.setAlignmentY(JPanel.TOP_ALIGNMENT); display_panel.setAlignmentX(JPanel.LEFT_ALIGNMENT); big_panel.add(display_panel); JPanel display_left = new JPanel(); display_left.setLayout(new BoxLayout(display_left, BoxLayout.Y_AXIS)); display_left.setAlignmentY(JPanel.TOP_ALIGNMENT); display_left.setAlignmentX(JPanel.LEFT_ALIGNMENT); display_panel.add(display_left); JPanel display_right = new JPanel(); display_right.setLayout(new BoxLayout(display_right, BoxLayout.Y_AXIS)); display_right.setAlignmentY(JPanel.TOP_ALIGNMENT); display_right.setAlignmentX(JPanel.LEFT_ALIGNMENT); display_panel.add(display_right); // get Display panels JPanel panel1 = (JPanel) displays[0].getComponent(); JPanel panel2 = (JPanel) displays[1].getComponent(); JPanel panel3 = (JPanel) displays[2].getComponent(); JPanel panel4 = (JPanel) displays[3].getComponent(); // make borders for Displays and embed in display_panel JPanel Border etchedBorder10 = new CompoundBorder(new EtchedBorder(), new EmptyBorder(10, 10, 10, 10)); panel1.setBorder(etchedBorder10); panel2.setBorder(etchedBorder10); panel3.setBorder(etchedBorder10); panel4.setBorder(etchedBorder10); // make labels for Displays JLabel display1_label = new JLabel("weighting function"); JLabel display1a_label = new JLabel("vertical level (Y) vs channel (X)"); JLabel display2_label = new JLabel("model atmosphere profile"); JLabel display2a_label = new JLabel("temperature (red), ozone (blue),"); JLabel display2b_label = new JLabel("water vapor (green), pressure (white)"); JLabel display3_label = new JLabel("weighting function difference"); JLabel display3a_label = new JLabel("vertical level (Y) vs channel (X)"); JLabel display4_label = new JLabel("brightness temperature errors"); JLabel display4a_label = new JLabel("with zero reference line and"); JLabel display4b_label = new JLabel("root mean square error (single point)"); // embed Displays and their labels in display_panel JPanel display_left.add(panel1); display_left.add(display1_label); display_left.add(display1a_label); display_left.add(panel2); display_left.add(display2_label); display_left.add(display2a_label); display_left.add(display2b_label); display_right.add(panel3); display_right.add(display3_label); display_right.add(display3a_label); display_right.add(panel4); display_right.add(display4_label); display_right.add(display4a_label); display_right.add(display4b_label); // make the JFrame visible frame.setVisible(true); } /** get observed brightness temperatures, as well as temperature, water-vapor mixing-ratio, ozone and pressure profiles */ class real_tbcCell extends CellImpl { public void doAction() throws VisADException, RemoteException { // get index into model atmospheres int in_dx = (int) ((Real) in_dx_ref.getData()).getValue(); if (in_dx < 1 || in_dx > 2234) return; // read observed brightness temperatures from data_obs_1.dat float[][] data_b = new float[1][19]; re_read_1_c(in_dx, data_b[0]); ((FlatField) real_tbc_ref.getData()).setSamples(data_b); // obtain climatological temperature, water-vapor mixing-ratio, // and ozone mixing-ratio profiles by interpolating in month // and latitude amongst the FASCODE model atmospheres; // also get fixed pressure levels float lat = data_b[0][18]; int month = 6; float[][] t_x = new float[1][40]; float[][] m_x = new float[1][40]; float[][] o_x = new float[1][40]; float[][] p_x = new float[1][40]; get_profil_c(lat, month, t_x[0], m_x[0], o_x[0], p_x[0]); ((FlatField) tempa_ref.getData()).setSamples(t_x); ((FlatField) mixra_ref.getData()).setSamples(m_x); ((FlatField) ozonea_ref.getData()).setSamples(o_x); ((FlatField) presa_ref.getData()).setSamples(p_x); } } /** compute weighting function of channel versus vertical level */ class wfnbCell extends CellImpl { public void doAction() throws VisADException, RemoteException { // get zenith angle and skin temperature float gzen = (float) ((Real) gzen_ref.getData()).getValue(); float tskin = (float) ((Real) tskin_ref.getData()).getValue(); // compute weighting function of channel versus vertical level float[][] t_x = Set.doubleToFloat(((FlatField) tempa_ref.getData()).getValues()); float[][] m_x = Set.doubleToFloat(((FlatField) mixra_ref.getData()).getValues()); float[][] o_x = Set.doubleToFloat(((FlatField) ozonea_ref.getData()).getValues()); float[][] p_x = Set.doubleToFloat(((FlatField) presa_ref.getData()).getValues()); float[][] wfn = new float[2][40*18]; goesrte_2_c(gzen, tskin, t_x[0], m_x[0], o_x[0], p_x[0], wfn[0], wfn[1]); ((FlatField) wfnb_ref.getData()).setSamples(wfn); } } /** compute brightness temperature errors and root mean square */ class wfnaCell extends CellImpl { public void doAction() throws VisADException, RemoteException { // compute brightness temperature errors float[][] t_x = new float[1][]; float[][] wfn = Set.doubleToFloat(((FlatField) wfnb_ref.getData()).getValues()); t_x[0] = wfn[0]; ((FlatField) wfna_ref.getData()).setSamples(t_x); float[][] real_tbc_x = Set.doubleToFloat(((FlatField) real_tbc_ref.getData()).getValues()); float[][] diff_DATA_x = new float[1][18]; float squ_mod = 0.0f; for (int c=0; c<18; c++) { diff_DATA_x[0][c] = wfn[1][0 + 40 * c] - real_tbc_x[0][c]; squ_mod += diff_DATA_x[0][c] * diff_DATA_x[0][c] / 18.0f; } ((FlatField) diff_ref.getData()).setSamples(diff_DATA_x); // smr is root mean square of brightness temperature errors smr_ref.setData(new Real(tbc_d, Math.sqrt(squ_mod))); } } /** save a copy of wfna in wfna_old */ class wfna_oldCell extends CellImpl { public void doAction() throws VisADException, RemoteException { // save a copy of wfna in wfna_old (i.e., wfna_old = wfna) wfna_old_ref.setData( (FlatField) ((FlatField) wfna_ref.getData()).clone()); } } /** compute diff_col = wfna - wfna_old */ class diff_colCell extends CellImpl { public void doAction() throws VisADException, RemoteException { // compute diff_col = wfna - wfna_old diff_col_ref.setData( wfna_ref.getData().subtract(wfna_old_ref.getData())); } } /** native method declarations, to Fortran via C */ private native void re_read_1_c(int i, float[] data_b); private native void goesrte_2_c(float gzen, float tskin, float[] t, float[] w, float[] c, float[] p, float[] wfn, float[] tbcx); private native void get_profil_c(float rlat, int imon, float[] tpro, float[] wpro, float[] opro, float[] pref); }