16.2. Povray

The Persistence of Vision Raytracer is a high-quality, totally free tool for creating stunning three-dimensional graphics.

Ray-tracing is a rendering technique that calculates an image of a scene by simulating the way rays of light travel in the real world. However it does its job backwards. In the real world, rays of light are emitted from a light source and illuminate objects. The light reflects off of the objects or passes through transparent objects. This reflected light hits our eyes or perhaps a camera lens. Because the vast majority of rays never hit an observer, it would take forever to trace a scene.

These kind of applications can be easily made parrallel by using pvmpovray. Pvmpovray expects to working on a Beowulf style cluster and spread it's load to other nodes using pvm. The openMosix way of doing this is the same, however we just do this on 1 machine and have openMosix do the load spreading work fo you !

A GREAT Howto on PVM Povray will show you how to setup PVMPovray. Below is a small summary.

$ cd pvmpov3_1g_2 $ tar xfz ../povuni_s.tgz $ tar xfz ../povuni_d.tgz $ ./inst-pvm Trying to apply the patch. Searching for rejected files $

Now compile with aimk ( which is a wrapper script provided by the pvm rpm , buth which probably won't be in your path.(some of the readers might remember aimk from other platforms / applications )

If you are on a RH 8.0 box id moved libpng and zlib to .notused .. This in order to prevent version issues .. with other libpng and zlib versions.

export PATH=$PATH:/usr/share/pvm3/lib export PVMROOt=/usr/share/pvm3

I then run aimk newunix. Then we start pvm and quit it. The daemon stays active..

And a last thing that is not known by a novice pvm user is that pvm does use its own paths, and you have to put pvmpov either in that path or launch it with the complete pathname.

[root@dhcp71 povray31]# /usr/local/bin/pvmpov -L /usr/src/povray/pvmpov3_1g_2/povray31/include/ +Iskyvase.pov +Oskyvase.tga +NT16 +NW64 +NH64 +v +w1024 +h768 Persistence of Vision(tm) Ray Tracer Version 3.1g.Linux.gcc This is an unofficial version compiled by: Jakob Flierl - PVMPOV Version 3.1g.2 The POV-Ray Team(tm) is not responsible for supporting this version. Copyright 1999 POV-Ray Team(tm) Never found section in file /usr/src/povray/pvmpov3_1g_2/povray31/include/. Initializing PVMPOV Spawning /usr/local/bin/pvmpov with 16 PVM tasks on 1 hosts... ...16 PVM tasks successfully spawned. Waiting up to 120s for first slave to start... Slave 0 successfully started. Parsing Options Input file: skyvase.pov (compatible to version 3.1) Remove bounds........On Split unions........Off Library paths: /usr/local/lib/povray31 /usr/local/lib/povray31/include Output Options Image resolution 1024 by 768 (rows 1 to 768, columns 1 to 1024). Output file: skyvase.tga, 24 bpp PNG Graphic display.....Off Mosaic preview......Off CPU usage histogram.Off Continued trace.....Off Allow interruption...On Pause when done.....Off Verbose messages.....On Tracing Options Quality: 9 Bounding boxes.......On Bounding threshold: 25 Light Buffer.........On Vista Buffer.........On Antialiasing........Off Radiosity...........Off Animation Options Clock value.... 0.000 (Animation off) PVM Options Block Width.... 64 Block Height... 64 PVM Tasks...... 16 PVM Nice....... 5 PVM Arch....... PVM Slave...... /usr/local/bin/pvmpov PVM WorkingDir. /usr/src/povray/pvmpov3_1g_2/povray31 Redirecting Options All Streams to console..........On Debug Stream to console.........On Fatal Stream to console.........On Render Stream to console........On Statistics Stream to console....On Warning Stream to console.......On Starting frame 0... Slave 1 at dhcp71.office.be.stone-it.com successfully started. Slave 2 at dhcp71.office.be.stone-it.com successfully started. Slave 3 at dhcp71.office.be.stone-it.com successfully started. Slave 4 at dhcp71.office.be.stone-it.com successfully started. Slave 5 at dhcp71.office.be.stone-it.com successfully started. Slave 6 at dhcp71.office.be.stone-it.com successfully started. Slave 7 at dhcp71.office.be.stone-it.com successfully started. Slave 8 at dhcp71.office.be.stone-it.com successfully started. Slave 9 at dhcp71.office.be.stone-it.com successfully started. Slave 10 at dhcp71.office.be.stone-it.com successfully started. Slave 11 at dhcp71.office.be.stone-it.com successfully started. Slave 12 at dhcp71.office.be.stone-it.com successfully started. Slave 13 at dhcp71.office.be.stone-it.com successfully started. Slave 14 at dhcp71.office.be.stone-it.com successfully started. Slave 15 at dhcp71.office.be.stone-it.com successfully started. 0:00:53 86.46 of blocks complete.Not using dhcp71.office.be.stone-it.com for reassignment (77%) 0:00:53 86.98 of blocks complete.Not using dhcp71.office.be.stone-it.com for reassignment (67%) Not using dhcp71.office.be.stone-it.com for reassignment (86%) Not using dhcp71.office.be.stone-it.com for reassignment (85%) 0:00:55 89.06 of blocks complete. 640 of 768 lines finished (in frame 0).Not using dhcp71.office.be.stone-it.com for reassignment (65%) 0:00:56 91.67 of blocks complete.Not using dhcp71.office.be.stone-it.com for reassignment (72%) 0:00:56 92.71 of blocks complete.Not using dhcp71.office.be.stone-it.com for reassignment (80%) 0:00:57 93.75 of blocks complete. Slave at dhcp71.office.be.stone-it.com has exited. 0:00:57 94.79 of blocks complete. Slave at dhcp71.office.be.stone-it.com has exited. Slave at dhcp71.office.be.stone-it.com has exited. 0:00:58 95.83 of blocks complete. Slave at dhcp71.office.be.stone-it.com has exited. 0:00:58 96.35 of blocks complete. 672 of 768 lines finished (in frame 0).Not using dhcp71.office.be.stone-it.com for reassignment (77%) Slave at dhcp71.office.be.stone-it.com has exited. 0:00:58 97.14 of blocks complete. 688 of 768 lines finished (in frame 0). Slave at dhcp71.office.be.stone-it.com has exited. 0:00:59 97.92 of blocks complete. Slave at dhcp71.office.be.stone-it.com has exited. 0:00:60 98.44 of blocks complete. 704 of 768 lines finished (in frame 0). Slave at dhcp71.office.be.stone-it.com has exited. 0:01:03 100.00 of blocks complete. 768 of 768 lines finished (in frame 0). Finishing frame 0...rtw. 768 Waiting for remaining slave stats. PVM Task Distribution Statistics: host name [ done ] [ late ] host name [ done ] [ late ] dhcp71.office.be.stone-it.com [ 5.21%] [ 0.00%]dhcp71.office.be.stone-it.com [ 7.81%] [ 0.07%] dhcp71.office.be.stone-it.com [ 8.85%] [ 1.17%]dhcp71.office.be.stone-it.com [ 4.69%] [ 0.00%] dhcp71.office.be.stone-it.com [ 8.85%] [ 0.98%]dhcp71.office.be.stone-it.com [ 4.17%] [ 0.00%] dhcp71.office.be.stone-it.com [ 5.21%] [ 0.00%]dhcp71.office.be.stone-it.com [ 8.33%] [ 0.52%] dhcp71.office.be.stone-it.com [ 5.21%] [ 0.00%]dhcp71.office.be.stone-it.com [ 5.73%] [ 0.72%] dhcp71.office.be.stone-it.com [ 7.29%] [ 2.73%]dhcp71.office.be.stone-it.com [ 4.17%] [ 0.00%] dhcp71.office.be.stone-it.com [ 5.21%] [ 0.00%]dhcp71.office.be.stone-it.com [ 6.77%] [ 0.13%] dhcp71.office.be.stone-it.com [ 4.69%] [ 0.00%]dhcp71.office.be.stone-it.com [ 7.81%] [ 0.00%] POV-Ray statistics for finished frames: skyvase.pov Statistics (Partial Image Rendered), Resolution 1024 x 768 ---------------------------------------------------------------------------- Pixels: 303104 Samples: 303104 Smpls/Pxl: 1.00 Rays: 1192710 Saved: 0 Max Level: 0/5 ---------------------------------------------------------------------------- Ray->Shape Intersection Tests Succeeded Percentage ---------------------------------------------------------------------------- Cone/Cylinder 1842227 900504 48.88 CSG Intersection 2742731 323346 11.79 CSG Union 1801008 521692 28.97 Plane 20223278 11233348 55.55 Quadric 1801008 1196533 66.44 Sphere 1801008 461786 25.64 Bounding Object 1842227 900504 48.88 ---------------------------------------------------------------------------- Calls to Noise: 1201944 Calls to DNoise: 2108954 ---------------------------------------------------------------------------- Shadow Ray Tests: 2856188 Succeeded: 85620 Reflected Rays: 889606 ---------------------------------------------------------------------------- Smallest Alloc: 9 bytes Largest: 20508 Peak memory used: 5643343 bytes ---------------------------------------------------------------------------- Time For Trace: 0 hours 1 minutes 7.0 seconds (67 seconds) Total Time: 0 hours 1 minutes 7.0 seconds (67 seconds)

As you can see the application was splitted into differen parts and run separatly, openMosix then did the job of balancing the load to other machines.

I had good results with 2 to 3 times the the number of cpu's I had available