Ai Write Color

This short tutorial covers how to use the Ai WriteColor node to add the output of another shader (for example the Utility shader) as a custom AOV.

The Maya scene is available here.


  • Assign a Standard Surface shader to a sphere. 
  • Connect a shader (like another Standard Surface) that outputs RGB to the beauty of the WriteColor.
  • Connect a WriteColor shader to the Color attribute of the Standard Surface shader.
  • Connect a Utility shader to the input of the WriteColor shader. Configure the Utility shader to output the value you want (e.g. Object ID):

Final shader network


  • In the 'Name' attribute of the WriteColor, select (or create) the custom AOV that you want to associate with the output of the Utility shader (for example 'ObjectID').


  • Open the Render Settings window and go to the AOVs tab. You should see the newly created AOV.


  • Render the scene. You should notice in your images folder that MtoA has written out both the beauty render and the Utility shader that is associated with the ObjectID AOV:

Example 1

Let's say you want to create some different mattes for your car model. The Ai WriteColor node can be a useful way to split up the model into different mattes. In this example, we will use Ai Write Color nodes for both the car paint and the windscreen glass.

Car beauty render

  • Create Ai Write Color nodes for both the car paint and the windscreen glass using the method used for the above sphere. Assign the car paint material and the windscreen glass respectively.
  • Select each Ai Write Color nodes and select the drop down menu next to Name. Give each Ai WriteColor node a new name such as Car Paint and Glass:


  • Render the scene. You should see that the car beauty has been rendered, including the car paint and windscreen images that can be used as separate mattes.
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