Enhancements to ElVis Scientific Graphics Software Tarun Pondicherry Ben Phillips PPPL Science Education Summer Interns Eliot Feibush – Mentor August 14, 2007

ElVis Overview Java based visualization software, graphs outputs of experiments, analysis, & simulation programs. Accepts input from Data Files Sockets - API GUI Presentation Styles Animated, Surface, Contour, + Reads data & displays graphs over Internet.

Monitor & Display Results DOE SciDac Fusion Simulations - under development CPES SWIM FACETS Web Services Reflectometer Simulation (ElFresco) – w3.pppl.gov/fwr TRANSP – RPLOT – beta test / alpha users GTC – available Shaped GTC – under development Nova-K – under development MSE TSC SCOPE

Summer ‘07 Improvements to visualizing 2-D data sets. Interactive log plotting. User requests from applications.

Tarun Pondicherry – my work Develop New Presentation Styles f(x,i) with color gradients f(x,y) Continuous color plots (color map) f(x,y,t) Indexed color plots Implement User Application Requests Aspect Ratio Resize ElVis File Convention Additions Animation Controls

Gradient Datasets Shows multiple time steps in order in a single view. Creates a linear gradient from first to last index. Useful to see how data changes over time. Animated Presentation Style New Gradient f(x,i)

Continuous Color Plot Displays a color profile of 2D data. Similar to contour, but shows all data points. Existing Contour Plot New Color Map Plot

Data Exploration Displays value as user moves the cursor.

Other Interactions Inherits ElVis interactions (zoom, pan, whiteboard, labels) for exploring and annotating data.

Log Scalable X, Y, and color axes independently scale logarithmically or linearly.

New Color Scale Chooser Allows users to specify color ranges. Add, delete or change a color point. Useful to draw attention to particular values. Color scale saved in ElVis convention. Useful for simulations & analysis programs to color-code plasma cross sections.

Indexed Color Map Plots f(x,y,t) During animation, moves through time dimension Creates images during animation Can be made from NetCDF Panel –Supports Templates –Supports NetCDF File Monitoring psiRZ for NSTX shot Data from Rob Andre. Click on image to play movie.

Animated  Images Saves steps in animated plots as a series of images. Can copy and paste all images into PowerPoint at once in order. Can easily be made into a wmv file using Windows Movie Maker. psiRZ over time.01 –.54 seconds

Aspect Ratio Resize Initial aspect ratio limited to 4:3 paper size graphs. Java AffineTransform used for resize --> Distortion Users requested gaining resolution and maintaining line width and aspect ratio. Now recalculates placement and increases resolution. Text aspect ratio also preserved. No distortion. Before:After:

ElVis Convention Additions ElVis convention allows users to save and open plots with presentation attributes (color, size, labels, etc.) Added functionality to save Contour, Surface, Color Plot, 2D Presentation Styles

Animation Controls Previously ElVis ran animations at the rate they loaded. My Additional Controls Runs at user defined frame rate. Dynamically sets frame rate based on server speed. Allows users to drop frames to maintain time base. CPES Sim. Vis. GTC Web Service

Animation Measurements Image Download Times for PC cppg-win2: –PPPL ~ 30ms –Rutgers ~ 50ms –Oak Ridge ~ 80ms Download rate for images stored as URLs on web servers.

Ben Phillips – my work Logarithmic plotting – graphical interaction. Improved surface plots of 2-D data sets. Application-driven features.

Challenges of Log Plotting Providing an interactive model ElVis Requirements Allow user to fine tune the viewing region Resize the graph window. Adjust the scales on the axes. Prevent user from “getting lost.” Enable the user to get a digital read out of specific values in a plot. Cleanly handle plots with values <= 0 Cannot take log of 0 or less.

Improvements to Log Plotting New features I implemented –Extended interactions of linear plots to logarithmic plots Tick marks Zooming Cursor –Created methods to handle the limitations of log plotting

Major and Minor Tick Marks Major tick marks specify decades (10 x, 10 x+1, 10 x+2, …) Minor tick marks specify points within a decade (2*10 x, 3*10 x, 4*10 x, …, 9*10 x ) Algorithm translated from rplot sglib Considers resolution to avoid crowding

Zooming – Allows users to examine areas of a log plot Click and drag region to zoom in.ElVis zooms in on the region and adjusts the axes appropriately.

Zooming – Graph must be at least one decade wide and tall I enforced minimum zooming region shown by red rectangle. This is the actual region that ElVis will display if the user lets go of the mouse.

Zooming – Axes limitations Users cannot zoom into a region that is less wide or less tall than a decade. Floating point precision bounds axes to the interval [10 -44, ]

Cursor – Digital Read Out Displays data values for each curve.

Challenges of Surface Plotting No 3-D graphics hardware acceleration. –No third party libraries such as Java3D. Heavyweight 3D components do not mix with Lightweight Swing components that support overlapping windows. ElVis must use 100% pure Java implementation in software. –Portable but slower than graphics hardware. –Must run in a browser. –ElVis cannot take advantage of the built-in memory and processing power present on many graphics cards.

My Surface Plot Improvements Logarithmic scales for axes Display Optimizations - Surface plots now display faster. Wireframe display during zoom, rotate, or resize. User can customize how much data is displayed dynamically. Memory Management

Log surfaces – Usefulness of log plots brought to three dimensions All three axes can be set independently to linear or logarithmic scales.

Wireframe Display Optimization Faster to rotate, resize, & zoom Makes rotating, resizing, and zooming smoother on surface plots.

Data Reduction Slider Even faster to rotate, resize, and zoom Users can control how much data to display while manipulating the surface.Demo

Surface graphs can take up a lot of memory! Problem is especially acute in Applets where memory is very limited. OutOfMemoryErrors crash ElVis –Unacceptable

Challenges of Handling Limited Memory Java’s garbage collector cannot be run on command. Java has a lot of behind-the-scenes implementation details dealing with runtime reflection that make estimating the size of classes difficult. OutOfMemoryErrors cannot be caught programmatically.

Consquences of Java’s Memory Handling Limitations ElVis must make an educated guess at the memory requirement for a Surface plot. –In practice it appears to be accurate to within 10% most of the time (20% off is the worst observed) Java memory handling features can still be broken in certain cases.

Surface plots are partially displayed when memory is low. Surface plots are only displayed with some of their polygons in low memory situations. If available memory becomes extremely low then ElVis does not allow any more Surface plots to be opened.

Java Memory Allocation Click on Run the ElVis Applet: w3.pppl.gov/elvis Browser applet limited to 64 MB. Run as application outside of brower = 200 MB click on Run ElVis Type in a command line: java -Xms Xmx elviscdf.jar = 900 MB

Adding more memory to Applets (On Windows + Java 1.5 or 1.6) Start -> Control Panel -> Java Plug-in -> Java Tab -> View Java Applet Runtime Settings Add a Java Runtime Parameter –Xmx[heapsize]m Example: -Xmx500m makes heap size 500 megabytes for Applets Java 1.5 can increase to ¼ system memory.

Points Editor Edit numerical values Fix spurious data. Created for fixing input profiles for the Nova-K web service.

Layout Manager Adjust the number of rows and columns Allows for easy manipulation of a large number of graphs. Collect & retain all graphs from an rplot session for comparisons.

Acknowledgements Thanks to –Eliot Feibush - Mentor, Slidesmith –PPPL Science Education Program: Christine Ritter, Andrew Zwicker & James Morgan –Princeton Plasma Physics Lab

Summary Improvements to ElVis foundation classes benefit display programs & web services that include ElVis. I want to thank Ben & Tarun for all the excellent work they have accomplished this summer.