Volume Lights in Mental Ray?

#1

Hi,

I’ve been trying to find out how to render volume lights in mental ray, and haven’t had much luck. Would anyone know how to do that - for specific lights and not the whole scene, as a fog or mist? It’s easy enough with Scanline, but with MR it’s something different…

Thanks for any help.

HL

It’s in 3DS Max, by the way :slight_smile:

#2

Is this what you are trying to achive?
http://cgnotebook.com/wiki/Mental_ray_for_Maya_parti_volume

#3

Something like that. The trouble is that when the PartiVolume shader is activated, the scene goes dark during render, and when done, adds the ‘misty’ effect - but to everything, while still going rather dark. I’m thinking the settings need a lot of adjusting. I was using a mr directional light, shaped like a cylinder, going from the sky to the ground, with a bluish scatter, however, it kind of went everywhere, instead of being confined to the light shape. Any ideas?

Thanks,

HL

#4

I think I understand what your problem is, although pictures are always helpful. From what I understand, you only want the volumetric effect applied to a small section of the scene? Just make the shape that you want it confined to (a cylinder in this case?) and apply your volumetric shader to that.

I assume you took a sphere or cube and enclosed your entire scene in that. If not, then disregard the next part.

It also sounds like you’re not applying the transmat shader to the material and shadow shaders. If the rest of your scene is going dark it’s probably because your geometry with the volumetric shader is blocking the light sources.

I use Maya, by the way, so it might be a little different. And, again, pictures would be more helpful because I’m having trouble visualizing exactly what your problem is.

Edit: I use this method to do volumetrics fyi: http://cgnotebook.com/wiki/Mental_ray_volumetric_shadows_with_parti_volume_in_Maya

#5

you can apply the surface shader on all the geometry then enclose the area with a transmat shaded cube and take a seperate render. in that way only the ray will get rendered you can simply add it on the comp.

#6

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