How do I make a light only illuminate a single object and nothing else in the scene?

winduptoy

Also the reverse:  How do I illuminate everything in the scene except specified objects?

So, for example, I have a scene that includes a gold sphere.  I want one light to only illuminate the sphere and nothing else, and I want other lights to affect the rest of the scene but not the gold sphere.

winduptoy

Oh, er, probably using iray here, and probably spotlights, if that matters.

Richard Haseltine

The appearance of a "gold" sphere is essentially going to be reflections of the other things in the scene, so i'm not sure your goal is practical. Still, in geenral the way to do this would be using Canvasses in the Advanced tab of Render Settings with Light path Expressions, one for each of the two combinations of lights and objects - when you saved the render a folder named for the render plus Canvasses would be created containing .exr files for each canvas layer, which can then be adjusted and combined in an image editor.

winduptoy

Thanks!  I'll change the sphere to blue ;)

brimstoneomega

Couldn't you make two renders and then layer them over each other in an image editor? Like take a picture of your gold sphere and the light you want for it, render it out in like a png format or another one that lets you set the alpha as transparent, then do the rest of you scene as you want it. Then take the image of your gold ball and add it as a top layer to the render of the rest of your scene and the merge it down. Then you can save it as whatever format you want, like a jpg that won't let you do the transparent alpha stuff.

 

SixDs

That is more-or-less what Richard was talking about, brimstoneomega, except he was referring to using Iray canvasses for the purpose, which is the kind of thing canvasses are designed for.

brimstoneomega

Oh! That's pretty cool! There's so much stuff you can do with Daz, I've barely even scratched the surface! Sem to learn something new everyday, kind of like this, thanks for clarifying!