Rendering in Parallel -- PVMPOV

The basics of raytracing

Basic raytracing

POV-Ray (=Persistence of Vision)

• official versions for various platforms
• free source available
• maintained by the POV-Ray Team (http://www.povray.org/)
• serial program
• previous scene, 640x480: 4 hours 40 minutes on SGI O2

PVMPOV = PVM + POV-Ray

Authors

• Brad Kline, Cray Research, Inc.
• Andreas Dilger (http://www-mddsp.enel.ucalgary.ca/People/adilger/povray/pvmpov.html)
• Harald Deischinger
• Jakob Flierl

• Embarrassingly Parallel Problem
• Similar to the mandelbrot set. We have
  • x by y independent pixel
  • an unknown amount of calculation per pixel.

Parameters

• blocksize, x by y pixel (Default: 32x32)
• #Tasks, n (Default: #Hosts)

Only n/2 spawns must be sucessful.

Block is reassigned if slave is slow.

Speedup = (exec time using 1 proc)/(exec time using n procs)

Image size: 640x480 pixel
Time for serial program on 1 SGI O2: 16800 seconds
16 SGI O2s for parallel test
Theoretical Speedup: 14 (12 full SGI O2s + 4 half SGI O2s, because already busy with 1 process)

The example picture, "First Strike at Pearl," was created by N.B. (beliaev@utu.fi) and Glenn McCarter (gmccarter@hotmail.com) and can be found at http://www.geocities.com/SoHo/Workshop/9193/index.html.

Raytracing Introduction pictures are taken from JK's POV-Ray pages at http://members.tripod.com/~klatte/pov/raytrace.html.

POVBench

irtc(Internet Raytracing Competition) and authors for the Animation After Their Last Supper