Out of curiosity: Is there an option to render polymeshes as volumes with vray such as presented here: Help ?
Would come in handy for our next gig and we are trying to anticipate as much as possible to be quick on our feet when it hits…
Any input is greatly appreciated.
cheers,
j
…more precisely: Is there an option to displace a volume with vray?
Hey,
Yes it is possible. Just load your volume cache using VRay Volume Grid. Then in the Rendering rollout, there is a Displacement option. You can use a texture loaded through a projection in order to get similar results to the one you have linked.
thanks for the heads up, georgi, will try that immediately. One more question: I will need to first export volume caches in any case, right? I.e. there is no option to convert closed polygons to be rendered as volumes as in Arnold?
again, thanks for your great support, guys, much appreciated!
You can render any mesh as a volume, by settings it’s surface shader opacity to 0/black and adding a ‘VRayEnvironmentFog’ as the volume shader (in the shading group). It also works with subdivision/displacement. You control the density of the volume with the Fog Distance/Fog Density parameters on the VRayEnvironmentFog node.
Mapping of the environment fog parameters (color, emission, density) can be done with 3d procedurals and vrayDistance textures.
Hi Dan, I am aware of that, but that way I will not be able to displace the volume
Why not? If you displace the mesh, the environmentFog will render the displaced mesh as a volume. Or am I missing something?
/edit:
.. Is it that you actually need to displace the ‘interior’ of the volume and not just the surface itself? In that case, you can ignore my suggestion 
You can totally do that. Here is a sample scene how this works with Env fog.
For the displacement texture make sure you have Alpha is Luminance turned on.
Displace_EnvFog.zip (11.8 KB)
Hey hey - first off thanks to the both of you for your suggestions, much appreciated!
With regards to the latter approach that was what I tried out first, but it yields totally different results as the ‘interior of the volume’ is not affected. Reading in volumes using VRay Volume Grid seems to work as far as I can tell right now, but I cannot find an easy way to make volumes inside of maya accessible through that as I first need to export a VDB or similar. Is that correct georgi, or am I missing something?
Indeed, that’s how it works for now. Using Phoenix FD will be quite easy to fill a mesh volume with smoke and displace that afterwards.
I think in the Arnold example, only part of the geo is being turned into a volume. I tried this a while back but couldn’t get anything like it..but thats probably down to my lack of understanding.