V-Ray Fog problem

[Robert]

Hi there,

I did not often used Vray Environment Fog, so I may missed a thing, but couldn't find any online help.

1. When I set a gizmo, like a box mesh, V-Ray does simple stop render the Fog, but still render the mesh like before. It seems like this is broken?
2. I tried to map a noise to the density, like in the examples. But no matter what I link I never get the density affected by the noise. I tried the RGB, Alpha and Value output. One the value output does somethings, but not what the noise is, more like a low general value. The fog color however works.
3. There is no output for the fog effect? Usually there must be a V-Ray Volume or Atmosphere output, but I can't find it?
4. Tried to affect the density of a fog, with the Scatter Volume shader, but it does nothing. (used vray Bercon and normal Noise)


Maybe someone can post an example.

[MutantPixel]

I have found that when rendering Vray Environment Fog and mapping a texture to the density channel, I have to first render a traditional render (not RT) to be able to 'see' it. And then for some reason after doing that, you can then see the texture in RT previews. I can't explain why but that has worked for me.

[Robert]

I solve the problem partly. I didn't you had to set the material to opacity = 0.0 to make it work. Anyway, still not being able to get a channel output.

[vladimir.nedev]

1. When I set a gizmo, like a box mesh, V-Ray does simple stop render the Fog, but still render the mesh like before. It seems like this is broken?

This is on purpose. In case you want to have an existing mesh act as a fog gizmo. For example, the walls of a room.
You already found the solution - use the opacity of the material to make it transparent.

2. I tried to map a noise to the density, like in the examples. But no matter what I link I never get the density affected by the noise. I tried the RGB, Alpha and Value output. One the value output does somethings, but not what the noise is, more like a low general value. The fog color however works.

I am attaching some example scenes of textured environment fog.

3. There is no output for the fog effect? Usually there must be a V-Ray Volume or Atmosphere output, but I can't find it?

It's under V-Ray Render Elements -> V-Ray Additional Outputs. I am attaching a screen-shot where it is.

4. Tried to affect the density of a fog, with the Scatter Volume shader, but it does nothing. (used vray Bercon and normal Noise)

I am not sure you can combine fog and scatter volume.

I have found that when rendering Vray Environment Fog and mapping a texture to the density channel, I have to first render a traditional render (not RT) to be able to 'see' it. And then for some reason after doing that, you can then see the texture in RT previews. I can't explain why but that has worked for me.

I don't think you have to start a normal render.
You just need to restart RT after you connect the texture to the fog.
Making the connection is not handled properly by the V-Ray for Modo RT update mechanism.

Greetings,
Vladimir Nedev

[Robert]

Thanks a lot. You should add that information to the online manual.