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Jose Miguel avatar image
Jose Miguel asked ·

control objects alpha

Hi there;

Coming from Mental Ray, I was used to do things in a different way.

I used to render my scene with regular opaque alpha for hero objects, and zero alpha for background (surface background, like a photography studio background).

But I can't find a way to do this with Arnold.

I know there is a "matte" option in the object's shape, but that forces the alpha channel to be zero, but makes the object completely black too, and that's not what I want.

I want the object to render as normal, but write black alpha channel.

Is that possible?.

Thanks in advance.

alpha for geometrymattes
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Sumit Kumar avatar image
Sumit Kumar answered ·

Hey,

I am not sure if you can do this thing in alpha But i can give you a way around,

if you are working with "standardSurface"

  • scroll down a bit in shader tab you will find "AOVs" sub-tab
  • Keep ID-1 (or whichever id you want to use) color to white
  • add id_1 aov to your AOV tab in render settings, you can also rename this Aov name
  • If or if not you renaming that AOV name, copy that name and go to you shader and put that name in "ID 1 AOV (or whichever id you using) "

now you will get you main beauty and as AOV you will get your alpha as you wanted.

Hope this will be helpful for you!!

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