We have motion blur turned on to properly black hole fume with the character geometry (man on fire), and FumeFX seems to be rendering with very low volume samples. We have been able to work around this by disconnecting the volumeSamples attribute on the ffxMRVolShape node and putting in the largest value that it reaches.
This issue affects render farms that load and render just one frame at a time, rather then a batch render that runs a whole sequence.
Hello,
With FumeFX 3.5.2 the Volume Samples are linked to the adaptive grid size and grid spacing, so it's hard to say what went wrong.
Does this happens only when motion blur is enabled?
Could you please create some simple scene that shows this issue and attach it to the thread?
Thank you.
Regards,
Kresimir Tkalcec
Attached you will find a simple scene that illustrates this problem.
If you open this scene and render it interactively, it renders correctly. The problem occurs when we send it to the farm with a render command like this:
/local/prod/autodesk/aw_maya2013/maya2013-x64/bin/Render -r mr -v 5 -art -proj /laika/house/jobs/ss_alchemist/cg/maya -cam camera1 -s 1 -e 1 -b 1 -pad 4 -fnc 3 -rd /laika/house/jobs/ss_alchemist/images/shots/alchdev/fumeMotionBlurTest -of exr -rl defaultRenderLayer /laika/house/jobs/ss_alchemist/cg/maya/scenes/shots/alchdev/fumeMotionBlurTest.ma
It seems that if you only render one frame, FumeFX isn't setting the volume samples correctly. If I was to render a range of frames on one machine, only the first frame would have the problem and then the rest would be fine. Due to the nature of our farm, where we are rendering each frame individually, the problem happens every frame.
If motion blur is turned off, Fume renders fine on our farm.
Thanks,
Karl
Hello Karl,
Thank you for the scene - we were able to reproduce it and we're looking for the solution.
I will post a message here when it gets fixed.
Thank you.
Regards,
Kresimir Tkalcec
I think this might be a limitation that comes with mental ray.
It needs to calculate motion blur based on information it calculates from the previous frame.
We are finding its very hard to get the correct result on shots that have fume at frame '1' and also getting a correct result rendered on the final fame of a shot (if fume present) without rendering a extra frame 'plus one'
and so rendering a 'scrap frame' so the last one renders correctly.
An FYI in case it helps.
