[HOU-1367] probabilistic volume rendering

[LeoYfver]

Need some help understanding probabilistic volume rendering. There is "Probabilistic Rendering" on the volume grid shader and "probabilistic volumes" on the render node. We get the most correct results(closest to mantra) when probabilistic rendering is off on the shader and probabilistic volumes are on. We get a bit weird and wrong results when both are off(cuts off to much density) and when probabilistic rendering is on and probabilistic volume is off we get the opposite(too much low denisty is rendered).

1. is the look supposed to change this much? it feels like it shouldn, just change the way it samples

2. has "Probabilistic Rendering" on the volume grid shader and "probabilistic volumes" on the render node anything in common except the name? they have the same name but the results in look and rendertime change alot based on being on or off.

https://drive.google.com/open?id=1id...YnYp1NSuW7DPG2

[Gosho.Genchev]

I'll check and come back with more info later today. Off the top of my head - the missing density in the final image could be caused by the Smoke tab -> Cut-Off parameter. It's greater than 0 so V-Ray doesn't slow down trying to sample density values of 0.000001 and such.

All the best!

[LeoYfver]

thanks for answering!

min visible opacity on the volume grid shader is 0. either way there is no other differences between the renders so the opacity look shouldnt change i think.

[Gosho.Genchev]

If that is the case then yes, definitely need to check this. Would it be possible to give us a single frame of the simulation - sending it to mail if you can't share publicly is fine too.

Thanks!

[LeoYfver]

of course! forgot to add the volume file

https://drive.google.com/open?id=1gv...Trvep3ekEQfuAM