volumetrics lights

[celmar]

hi!!!   is it possible to get a SINGLE light in volumetrics, visible as a light cone, the other lights being normals, without volumetrics effect... i know it's no-realist, but on my actual picture, it would be handy! I want to have my character  normally lighted, and behind him a volumetric light, creating "ray's gods" with his legs, like a projector in theater with smoke, the other being unaffected... is it possible?

[Ealexander]

Not if you use Volumetrics globally via the render settings. But you can create a cone, apply a volume material to it and light it. Not ideal, but experiment with that.

[TomG]

If you set up an object with the volumetric material (rather than use the global volume material), you can Exclude that object from any lights that you don't want to show up with volumetric results (or reverse that and set up an Include list, if that's easier, sounds like it would be here). Note that the camera has to be outside this volumetric object, which is the only thing to keep in mind for this.

You could also composite in post, with a second render set up specifically for volumetrics (could use a Volumetrics pass in the multipass, to exclude any diffuse, etc from the result), or even using the C4D native volumetrics there and compositing.

[TomG]

Here's a quick example, with the blue light excluding the volumetric cube, and so no volumetric results show from the blue light (but it would continue to light the rest of the scene normally).