Environment fog and VDB smoke issue

[woytha]

Hello,
I start using VrayEnvironment fog instead of VrayAerialPerspective as it has some strange interaction with background.
However, I am getting again some weird behavior - the evnrionment "takes over" the smoke in some areas.
I tried to fiddle with "stepsize" on shader and with cutoff on Environment fog but so far no luck.
Is there a way how to overcome this?
Thanks,
Vojtech

[Gosho.Genchev]

Hey woytha ,

That's a known issue (and it's hard even calling it an issue because it's just how things work) - they way to resolve it is to set the Mode of the volume shader for the VDBs to Volumetric Geometry. Could you please give that a shot?

The reason this happens is that with envrionment effects (i.e. volumetrics), there is no way for the render engine to determine which effect should be in front of the other along the ray.

Hope that helps!

[woytha]

Hey woytha ,

That's a known issue (and it's hard even calling it an issue because it's just how things work) - they way to resolve it is to set the Mode of the volume shader for the VDBs to Volumetric Geometry. Could you please give that a shot?

The reason this happens is that with envrionment effects (i.e. volumetrics), there is no way for the render engine to determine which effect should be in front of the other along the ray.

Hope that helps!

Thanks, it works as intended if I change to Volumetric geometry. But also shuts down Houdini before finishing rendering :-/

[woytha]

Those crashes with Volumetric geometry rendering actually happened to me before.
But it is difficult to "cut it" from the scene. If I just use the same vdb sequence with environmental fog its OK.
When I add some instancing trees, crowds and grass it crashes. But it is not so heavy, the scene takes like half of 64gb RAM when rendering. I am trying to isolate where exactly this is happening.

[woytha]

Ok, so it is instanced trees which are sending Houdini down (together with volumetric geometry mode of rendering of smoke).
I will try tomorrow to isolate somehow the issue more precisely.

[Gosho.Genchev]

Hi woytha ,

Are the trees by any chance generated with the SideFX Labs tool? One of my colleagues reported an unusually high RAM usage with this asset which I managed to reproduce but fixing it was left for a later time. If so, we'll look into it asap.

Best regards!