Is random walk volume scattering possible?


#1

I was going over the various issues that stepping produces in cycles
( https://developer.blender.org/T56925 and Is there ever going to be a fix for non-homogeneous volume stepping in cycles? )
and I came across the idea of adding random-walk SSS, and I began wondering if it was possible to do something similar with volumes instead of stepping. I understand that it would most likely result in more noise/longer renders, but I think if something like that existed, it would be better for reducing noise for multiple scattering events in dense volumes. I also think houdini uses it, so there should be a way.


#2

Random walk SSS is effectively a simplified version of our volume scattering code, where the volume is assumed to be homogeneous. Volume stepping issues are about heterogeneous volumes, so quite different.


#3

ah, I was afraid of that. well, perhaps at some point we’ll have a solution that’s fast with multiple scattering events. maybe a little “research” in how houdini or other programs do it can help. I wasn’t necessarily mentioning it for the stepping issues I was talking about earlier, but I’m always working with volumes, so I’m always trying to find ways it might be made better, even if I understand someone probably already thought of it. I’m not the best at looking through code, much less blender’s, but maybe some day I’ll be able to help with these things.