Volume Grid not rendering correctly with Environment Fog

[MutantPixel]

I'm rendering out a scene with a bunch of Volume Grid VDB files, and I'm using the Environment Fog option, but it appears that any area of the VDB that renders over distant geometry has the incorrect depth/fog amount and produces a wrong result. is there a fix for this in some setting I hope?? If I disable the fog it all renders correct, but loses the nice depth added by the atmosphere.

[vladimir.nedev]

I think this is an issue with GPU rendering only.

As far as I know, the only solution is to replace your fog with a volume grid with constant density.

More info here : https://forums.chaosgroup.com/forum/...environmentfog

Greetings,
Vladimir Nedev

[Muhammed_Hamed]

On another note, this is solved in Vray 5 which is great!

[MutantPixel]

Thank you for the response Vladimir, apologies I didn't detail my setup better. The sample I showed above was rendered with the CPU using Vray Next for Modo 4.30.00. Just for testing, I tried rendering it again this evening with the CPU bucket renderer and got the exact same results-

[vladimir.nedev]

Hm, we will need a scene in that case.
Can you send it to Boyan so he can investigate.
His e-mail is boyan.nalchadjiiski@chaosgroup.com
Edit: CC it to me too please.

Greetings,
Vladimir Nedev

[MutantPixel]

I'll try to simplify the scene to just the elements with the rendering error and send it off this evening. Thanks.

[MutantPixel]

So I'm trying to figure out a way I can 'fix this in post' and have it still look good. It seems that the V-Ray Render Mask doesn't support being connected to a Volume Grid item, so is there some way i can generate an alpha of just the VDB volume to use to comp it into a clear background?? I can't just turn off the geometry because the volume overlaps the geometry. Help.


(I ended up just turning all surfaces solid black and turning the volume grid items solid white. Far from perfect solution, but got me an acceptable result)

[boyan]

Hey,

I would like to add this post only to show a workflow in case someone else struggling with that one.

Cheers,