Re: Render Farm

[dld@cmb.usc.edu (Drake Diedrich)]

On Mon, Feb 20, 2006 at 11:50:07AM -0300, Javier O. Augusto wrote:
> Hi List,
> 
> I have been told to search for viable options in "render farming" in my 
> University. The lab who actually does the design uses 3DStudio Max + 
> VRAY something.. I  thought maybe running a Debian Beowulf  + MPI + 
> POVray  to solve this  problem.
> Has anyone already done that? Is it possible or am I missing something?
> 
> I'd be very grateful to hear some comments. Thanks in advance.
> 
> Regards,
> Javier


   If VRAY is Povray, the older Debian povray (~3.0 IIRC) was already
patched and linked against PVM for distributed rendering.  Newer versions
aren't.  However, raytracing is embarrassingly parallel, and you don't need
to use a message-passing version of povray to get parallel speedups.  Just
use flags (H,W,SR,ER,SC,EC) to manually tile the image - eg. for a 640x480
image, send four 320x240 quadrants to 4 different machines and then paste
the output files back together.  If you have multiple images to render (for
an animation for instance), it's even more efficient to send each individual
frame to a different compute node, saving on parsing and communication time. 
You don't get the cool interactive display of mpipov/pvmpov where you watch
tiles arrive, but in bulk production it's slightly faster not to do that
anyway.

Beware of antialiasing when rendering tiles of the same frame (whether
manually or with message passing).  Adaptive antialiasing may not be
happening at the boundaries.  Antialiasing is another reason for animations
to stick to whole frames per compute node.

-Drake