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View Full Version : Compositing Dielectric with Absorption in the Alpha Transparency.



evolross
10-09-2012, 10:09 AM
I have an object using dielectric with absorption and I'm getting a nice dark center with a great falloff to the edges of the glass object. The problem is when I go to composite this on a plate, the absorption isn't reflected in the alpha of the object. It's fully black or "completely transparent" because technically the object is completely transparent. But the absorption makes it somewhat opaque in the center in the RGB render.

Is there a way to have the absorption color show up in the alpha of the object? Otherwise there's no way to composite this. In this situation I can't "bake" the background into the object as it's for a motion graphics project and the background will be moving independently. There's no refraction in the object so I don't have to worry about that.

I need to have the object's alpha actually be "somewhat transparent" so it comps nicely over whatever it's put over but retains the dark center... any ideas?

So far, I can't recreate the look I want using standard LW surfacing. I really like that center absorption.

BTW: There has to be something broke with the new forum's search... no matter what I search for, I get like 10 results from 2012 and then four pages of results starting in 2007 and earlier. Such a bummer NT.