1. Spiegel - A Visualization System for Stellar Systems Hans-Peter Bischof/hpb@cs.rit.edu David Merritt/drmsps@rit.edu www.grapecluster.rit.edu

2. Thanks To … Physics Department Peter Berczik Andras Szell Students 20043 Andrew Rader Tim Peterson Christopher Stelma Josiah Allen Jin Fang Zhang Jason Diamond Trevor Blanarik John Kaeuper Christopher Daniels Lewis Denizen Students 20042 Andrew Rader Tim Peterson Christopher Stelma Pat Villacin Lewis Denizen Josiah Allen William Yu Andrew Bak Jin Fang Zhang Trevor Blanarik Students 20041 Jonathan Coles Andrew Rader Raun Krisch Andrew Bak Christopher Stelma Peter Weisberg Meng Jiang Prachi Shinde Students 20034 Jonathan Coles

3. Agenda Visualization Systems in general Spiegel Data Reduction Future Data Provided by –David Merritt –Peter Berczik –Andras Szell

4. What I know about… CSMathAstro Physics

5. Stolen From Piet

6. Visualization System Visualize facts and not assumptions –Interpolations are assumptions Expert knowledge is needed Visualization systems have to be flexible

7. Spiegel A visualization system for stellar systems Controlled by a language Distributed No special hardware required

8. Demonstration % make 8 load./rknbody8b.sim camera new 1 "1" camera new 2 "2" camera new 3 "3” camera 1 lookat 0 0 0 camera 2 lookat 0 0 0 camera 3 lookat 0 0 0 camera 1 moveto 4 0.2 0.2 camera 2 moveto 0.2 0.2 5 camera 3 moveto 0.2 5 0.2

9. Visualization System 1 0 0.2 0.3 -0.4 …… 2 0 …….. …….. Post ProcessingFile []

10. Where does the Data come from: gravitySimulator 32 dual-Xeon PC nodes 32 grape cards 4 Tflops 14 Tbit disk space Gigabit Interconnection

11. Problem Description Visualize Dense Stellar Systems: –File Format # particles simulation time { id i 0 x y z a x a Y a z … }+ 1 ≤ i ≤ n, id i  IN { id i t i x y z a x a Y a z … } * id i  IN, t i  Double –File size: > 10GB –Standard hardware

12. Data Reduction Pre-Process –Extract what is needed Id time x y z color –Binary output Increases I/O speed ~ 3-5 times

13. Communication A simple language controls the system The language consist of primitives More sophisticated tools use this language to solve complicated tasks The language can be used to experiment

14. Sprache Designed to be open Sprache is German for language - credit to Jonathan Coles Example: –camera new 1 –camera 1 moveto 1 3 4 –camera rotate x y z –camera up x y z –…. Allows to recreate ‘scenes’

15. Intended Use of the Language GUI produce simple statements More sophisticated tools allow to do more sophisticated tasks –Moving through the system –Focus on specific areas –etc

16. Use of External Tools - How Produced by Tim Peterson

17. Use of External Tools - Stmts load../../../theSimulation.sim14003.color.compact.binary.Z camera new 1 "ll" updateview setDeltaT 0.003 camera 1 moveto 2 -2 2 camera 1 lookat 0 0 0 thisPointInTime 0 updateview camera 1 moveto 2.0588 -1.93882 2 updateview camera 1 moveto 2.1152 -1.87533 2 updateview camera 1 moveto 2.1692 -1.80963 2 updateview camera 1 moveto 2.2208 -1.74182 2 updateview ….

18. Use of External Tools - Movie Produced by Tim Peterson

19. Input/Output

20. Interpolation/Extrapolation Interpolation Two data points are needed Extrapolation –One data points is needed y t tltl trtr t y t tptp t

21. Interpolation in Work Data created, with  t = 0.1  t for the visualization was 0.01, no interpolation  t for the visualization was 0.01, with interpolation

22. Interpolation in Action

23. A Movie ….

24. Dehnen Model

25. Plummer Model Data provided by Piet Hut

26. Future Work - CS point of View Coloring/Highlighting based on physical characteristics –Mass –Speed –Velocity –Energy Add more sophisticated visualization technique - 10MB particle… Create a better language –follow bh 1 and look at 0/1/2 –trace bh 1|2|3 –show density in increments of 1 –I need to talk to you … Visualize more kinds of data –Means your data

27. Future Work - What do you think of This? Visualization of non visual aspects –Density - kernels –Gravity Lines - splines? –Gravity Waves - no idea? What will help to understand the system better? Can you visualize what you do not understand/know?

28. Future Work - Standards Format: –Plain Text Needed for large Simulation, because of file size Not extensible –What is if you would like to add information? –XML Great for smaller simulation Extensible Would be my favorite for small systems

29. Questions/Comments