View Full Version : Color id pass from maya selection issue in ps

08 August 2011, 10:38 AM
I have an issue with color id passes I render in maya.

Whenever I try to recuperate the color selection, whether it is using the select color range or the magic wand, I am unable to get a clean selection and always end up with a fringe or too hard of an edge.

When I render an alpha pass all I do is control click on the layer or use it directly as a mask which gets me a perfect selection. But when using a color id pass with multiple colors I cannot recuperate the different parts without a bad edge.

see issue here:

I tried playing with the edge contrast option in the maya render tab and with selection tools in ps but with no luck.

How do you achieve a proper id pass in maya and a proper selection in ps?

08 August 2011, 06:08 PM

Are you rendering a Coverage pass with your Label pass? The Label pass is aliased (not anti-aliased) so you need the Coverage pass which provides your edge. Check out this blog post on these two passes, it might help. This particular post uses these 2 passes in Nuke but you may find a way to translate the methods into PS.

Hope this helps!


08 August 2011, 12:53 PM
Actually I was just rendering a beauty pass with different surface shaders assigned to the objects so I guess that was the issue.
Thanks for the link I did not know you could separately stores anti-aliasing data in a render.
I tried the tutorial and got the separate file to render but with no information on it.
Not a straight forward workflow to me so I have a hard time doing it but I will redo it until I get it right.
thanks for the help!

08 August 2011, 05:40 AM
While I understand the benefits of using color-based object passes, I've always found it best to just output a matte-pass based on either the object's shape node or the material shader for a set of objects. You get a much higher-quality grayscale, no bit-depth limits (32bit is plenty), and you don't have to struggle with screen-space RGB stuff. They work just like the alpha channels you're used to, really.

Just an idea.

08 August 2011, 12:08 PM
Sounds great InfernalDarkness (, so let's say your camera view is completely occluded with objects, you still get an alpha pass per object based on their respective shape node?
How do you do that?

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