VolumeGrid questions and issues

[Seraph135]

We are using the VolumeGrid to bring vdb's created in Houdini into Max for rendering. We are creating enormous landscapes and using Houdini to create cloudscapes for them.

We're noticing that vray's own EnvironmentFog does not affect the VolumeGrid clouds. Is there something we maybe aren't doing right? or is it not possible to have one affect the other currently?

Also, we're trying to create a comparable shader in max for the clouds to what we can do in Houdini. One of the things we are having issues/questions about is displacing the volume. We would like to do the following....

Generate some noise and add it to the sampled position, and then apply that value as displacement. Then do that in a loop, so that for a certain number of iterations we keep sampling the same voxels and pushing them through a noise field over and over again. This will help get noise that curls around instead of just going in straight lines, for a better wispy look.

Any information on these issues would be greatly appreciated.

Thanks,

Tim J

[vlado]

The volume grid and the environment fog don't talk to each other right now. What are you using the fog for? Just haze? Rendering the two separately into a deep file and merging in Nuke is the only thing that comes to my mind right away.

For the displacement question, I hope one of the Phoenix guys can answer.

Best regards,
Vlado

[vlado]

Or actually you could replace the env. fog with a large volume grid gizmo...

Best regards,
Vlado

[Svetlin.Nikolov]

Hello,

You can use the displacement in 'Advection' mode of the displacement (you can try with 'Vector' mode too, but in general it gives worse results for smoke). You have to pass it a 3d texture containing the offset in R/G/B (from -1 to 1), and you have to calculate the displacement offset with the effect you want in the max editor - we don't support multiple displacements over already displaced content currently. It sounds like an interesting idea to look at in the future...