Render lights only?

er title probably don’t make sense but not really sure how to call it.

Anyway for compositing I read stuff about the rendering only casted shadows on an object, which is fine and dandy but how about rendering sort of light values on objects…?

most obvious case in point is if you want to composite an object that emits light into a picture / video clip

is it possible in blender? if not then how does one usually compensate for such things?

sorry if this has been asked before but as I said, I don’t really know how to call it so its a bit hard to search for

thanks in advance

just crossed my mind after rereading my own post several times…

hmm i guess it would be possible to render a scene normally to be lit and use that as info to tamper the levels / etc of the original scene?

I don’t kow if I understand, what you want to do.
But you can do this, by creating a Renderlayer with just the passes active you need.
For example only diffuse or specular or .
And you can make lights active in single layers only (Can help as well)


ah actually I think thats exactly what I was looking for thank you very much, even allowed some other questions I had answered to boot.

Should be fine now, will ask later if still get problems.