Inconsistent Output During Network Rendering

Inconsistent Output During Network Rendering

Post by caj00 » Fri, 08 Oct 2004 08:27:05


I'm getting kind of frustrated!

Rather than use Skytracer, I came up with a pretty cool procedural
texture for skys. It renders very quickly; faster than skytracer, but
renders inconsistently when rendering using ScreamerNet.

Any ideas as to why this is happening or what to check for? Is this
an undocumented "feature"?
 
 
 

Inconsistent Output During Network Rendering

Post by James Will » Fri, 08 Oct 2004 08:57:14


What exactly is 'inconsistent' about it?

jw.

 
 
 

Inconsistent Output During Network Rendering

Post by Tuvok Shak » Fri, 08 Oct 2004 12:06:08

Switching email accounts here.... the clouds are not in the same
location between frames.

On Wed, 06 Oct 2004 23:57:14 GMT, James Willmott
 
 
 

Inconsistent Output During Network Rendering

Post by Ian Brow » Fri, 08 Oct 2004 18:15:49


Not sure why a procedural texture would render inconsistently. However, if
it renders 'very quickly', is it possible to render it on one machine, then
comp it into your scene afterwards?
 
 
 

Inconsistent Output During Network Rendering

Post by James Will » Fri, 08 Oct 2004 20:28:00


I seem to recall a thread regarding the difference in random number
generating (for procedurals amoung others) across different
hardware/software. ie. AMD, Intel, Linux etc. Am I remembering correctly
and could this be the problem?

Or is the procedural looking the same across all renders with just the
location being different?

Or have you got World Coordinates turned on for a skybox that is
parented to a moving camera?

jw.
 
 
 

Inconsistent Output During Network Rendering

Post by Tuvok Shak » Fri, 08 Oct 2004 23:19:08

That's probably what we're going to have to do... render it out on one
machine, then composite it back in.
 
 
 

Inconsistent Output During Network Rendering

Post by DarkScienc » Fri, 08 Oct 2004 23:46:39

There used to be render differences with Alpha CPUs as their random number
generation was different than Intel and Mac systems. NewTek did fix this
issue though. Anyway, there are no render differences between platforms
with LW now as it uses the same RNG code on all platforms.

Sounds to me like the RNG seed value is getting lost when the scene is
loaded up on his render nodes. I guess if Tuvok could post his scene (or a
portion of it) maybe some of us could take a look to see what's going on.
There could be a glitch with his scene or surface files -- did he recently
change LW versions in the middle of this project? Or it could be a network
path error within his render farm setup... It could also be an issue of how
the texture orients itself to the rest of the scene (World Coordinates
possibility you mentioned).

Another possible workaround besides rendering on one system and comping
would be to bake the procedural sky texture - but if he needs to animate the
texture over time, then that won't work. If he hasn't done so, he may need
to save the sky texture out as a surface file so that way it's on disk with
the proper starting seed value right there in the file.