Camera clipping plane and Atmospheric volume light problem

[Morne]

Hi all

I have another one of those "impossible" things I'm trying to solve. I'm using a VRayPhyscam with clipping enabled and 4 spotlights with atmospheric volume light effect. (I tried with normal cam and same issue)

As you can see in this top pic I have 4 spots (110 hotspot angle) positioned at 45 angles around a box (hidden here) pointing outwards. You can see the 2 lines representing my clipping planes of the "side camera"



As you can see in this side pic, the clipping planes doesn't do ANYTHING to the volume light, as it should be in the "photoshopped version" The clipping planes are correct as my central box (hidden here) does get affected, but not the volume light.


Please help (The camera is animated so I can't cheat it any other way besides clipping plane) Any thoughts?

Regards,
Morne

[DanielBrew]

Geometry with 'visible to camera' unchecked will still cast shadows and obscure volume light. Could you use a pair of animated boxes with their position linked to the camera's cut planes?

[Morne]

Geometry with 'visible to camera' unchecked will still cast shadows and obscure volume light. Could you use a pair of animated boxes with their position linked to the camera's cut planes?

Thanks for the idea, but it doesn't seem to be working

[vlado]

From what I can see this does not work in the scanline renderer or mental ray either. However in V-Ray, at least the far clipping plane works. So if you render an image without clipping planes, and subtract from it an image with near clip set to 0.0 and the far clip set to the near clip that you want, it may work.

Best regards,
Vlado

[Morne]

From what I can see this does not work in the scanline renderer or mental ray either. However in V-Ray, at least the far clipping plane works. So if you render an image without clipping planes, and subtract from it an image with near clip set to 0.0 and the far clip set to the near clip that you want, it may work.

Best regards,
Vlado

How would I go about "subtracting" one image from another? Is it something I can do with Photoshop or Combustion?

[vlado]

Combustion should be able to do it, but if worse comes to worse, use the VRayCompTex texture inside 3ds Max with the already rendered bitmap images as sub-textures, and the mode set to "Subtract". You can then render the texture from the material editor (right-click on the material preview > Render texture... option).

Best regards,
Vlado

[Morne]

Combustion should be able to do it, but if worse comes to worse, use the VRayCompTex texture inside 3ds Max with the already rendered bitmap images as sub-textures, and the mode set to "Subtract". You can then render the texture from the material editor (right-click on the material preview > Render texture... option).

Best regards,
Vlado

Thanks Vlado I'll give that a try, just now I thought of trying with geometry cones with opacity mapped textures instead of lights with volume fog.....

[Morne]

how can I view the VrayCam clipping planes in viewport? I can't see from the side how far it goes, only in the cam viewport?