View Full Version : Shadow Alpha Maps?

Mike Pauza
01 January 2009, 10:00 PM
Any easy way to generate shadow alpha maps (GI & light based) without rendering everything set to white, then using select by color in Photoshop? Fairly sure the render buffer can't do that.

Have to make hundreds of pngs with alpha based shadows, and doing it manually isn't something I'm looking forward too.

Any help is much appreciated. -Mike

01 January 2009, 11:28 PM
That may be done through surface NE + DP ExtraBuffers or more easily, I think, with DP Filters NE. This thread ( could give you some ideas.


BTW, those solutions are more useful for GI shading since we can set up (Surface Editor) alpha channels to shadow density.

Mike Pauza
01 January 2009, 03:47 PM
I'll give it a look. Thanks gerardo.

For anyone interested I learned that the "shadow density alpha channel" setting in the advanced tab in the surface editor allows the alpha map for that surface to be computed using only shadows, which is exactly what I wanted.


01 January 2009, 08:03 PM
in image processing select render buffer export. set it up for a shadow pass, and it will give you black and white images with your shadow being white everything else being black. Bring the sequence into a composting application and tell it to make one of the rgb channels the alpha and you will have a shadow alpha map.

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01 January 2009, 08:03 PM
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