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Kate Pf avatar image
Kate Pf asked ·

How do you render a flat color AOV pass with the aiStandard hair shader

Hello, I was following a tutorial by Adam Skutt that utilized the alHair shader with Arnold 4. I'm using Arnold 5 with Maya 2018 using the aiStandard hair shader instead and trying to figure out how to render out a base color pass of my hair.

I'm using melanin to color the xgen hair, and can't figure out how to render a flat color pass (without influence from shadows or spec). Every AOV option available that seems related to color renders as black. There was an AOV option called "diffuse_color" that worked with the alHair shader in Adam Skutt's 2017 tutorial, but it doesn't exist in Maya 2018. The Beauty render pass has the color so the renderer has to be getting it from somewhere.

renderaovhair
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Bruno Rantin avatar image
Bruno Rantin answered ·

If I understand you correctly, you want the hair albedo as an AOV.
You need a custom AOV with a light path expression (LPE).
For that, create a custom AOV, name it RGBA_hair for example and add the following to the LPE: C<RS'hair'>.A
Like so:

Also, keep in mind that arnold's aiStandardHair is different, and its color comes from the specular layer, not the diffuse. Usually the diffuse component for StandardHair is black and all of its color comes from specular, unless you use some of its artistic attributes, increasing the diffuse weight that is zero by default.


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Kate Pf avatar image
Kate Pf answered ·

@Lee Griggs

I'm not sure I understand what you're referring to. I don't see mentions of rendering flat color passes on that page. Could you be more specific?

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Lee Griggs avatar image
Lee Griggs answered ·

There is an AOVs example here. You are getting black using it this way?

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