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View Full Version : mental ray - skylight shadows on a separate pass?

-Vormav-
02-24-2005, 08:03 AM
Hey. I've been wondering about this one for awhile, since I've never been too pleased with the effect of the skylight, and haven't found any easy ways to tweak it.
Anyway, from what I can tell, the shadow render elements for Mental Ray don't include any of the shadows cast by a skylight, and a matte/shadow material doesn't seem to pick it up either. Anyone know of a good way to isolate those shadows in a render? Is a lighting pass the best way?

~V
pcbyers
02-24-2005, 04:49 PM
Since a skylight just creates a global wash of GI, it won't give you true shadows, that is, shadows cast onto something. I had pretty good results with doing a "Plaster Pass" - that is, overriding everything with a 129 gray, 10 spec level, 10 gloss plaster material, and doing a full (non-render-element) pass. I actually added in cast shadows to that pass, but you could probably get better results with a separate shadow pass. Take your skylit white plaster frames into Combustion, create two identical channels out of them, and apply two different blend modes, so one lightens and one darkens your model. That way, you can tweak the highlights and shadows to what you need. And sliding that control in Combustion to deepen your GI shadows just right gives you a nice warm fuzzy feeling.
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