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I don't know you setup but this sounds like a case for booleans. But a pure material solution would be nicer for sure.

it's quite simple, the bubble must have the same material of the fog volume, in fact the inverted normals are for defining where the fog is ended
ciao beppe

I was just going to try something similar. Nice to know, thanks!

linvanchene wrote:Case 4:

In the scene are

- Cube with fog volume applied
- Camera inside fog volume moving through it
- "Protective" Bubble Sphere around camera to separate fog volume from camera - Material settings = ?

Hi linvanchene,

So in this case you wish to limit the extent of the fog in your scene but still have the camera move through it?
The previous answers about booleans and applying the same fog material to the bubble are correct. Don't think of it as 2 fog volumes, think of it as one volume with a bubble in it where you place the camera or if it's easier to visualize picture it with the bubble only half intersected with the cube, that still gives you one fog volume with a concave dent in the side. There is no difference as far as the renderer is concerned between this and if the bubble is in the center of the cube. It may seem counter intuitive but it makes sense when you think about it and it definitely works. In less time than it took me to type this I did a quick test to make sure, it never hurts to just try something. What's the worst that can happen?

T.

Hi,

TBFX is right.
Octane sees materials, rather than objects. The scene is a bunch of surfaces with various materials applied. (With the advent of object properties the notion of objects has entered octane but for the fog volume this does not matter).
In this case, the sphere (or cube) around the camera, so long as it has the same material applied, for all practical purposes in octane, is the same "object".

Think of it in ray tracing terms. When a ray goes through a surface with the normal facing it, it is entering the volume, and when it goes through another surface with the same material, with the normal away from it, it is exiting the volume. So the sphere around the camera with normals pointing inwards, is defining the 'exit' surfaces, therefore the camera is no longer inside the fog volume.

This is, at least, how i understand it...
Hope that helps.

Thanks
Chris.

I hate to confuse the issue, but. You might want to try NO fog volume geometry. Just have the bubble around the camera with the fog material, and the normals reversed. This also seems to work, although I don't know if there are any issues with doing it this way - other than how simple it makes everythign.