We will cover a way to write custom color information (set as the beauty render) triggered by an Ai Utility shader to a particular AOV. If you want to have, for example, 'Object ID' as one of your AOVs.

The Maya scene is available here.

The Ai WriteColor shader can also be used to achieve a similar effect.

• In the AOVs tab in the Arnold render settings, Add a custom AOV called ObjectID.

• Assign a standard_surface shader to an object.
• Create a utility shader and set the color_mode to objectID:

• Go to the Shading Group where the standard shader is connected. In the Arnold section, you will see an objectID attribute under Other AOVs:
• Drag and drop the Utility shader from the Hypershade to the objectID attribute in the Shading Group.

_{Drag Utility shader onto ObjectID of standard_surface SG}

The Ai Utility that is connected to the custom AOV will only be executed in objects with that particular shader.

Now the custom 'ObjectID' AOV will get its value from the Ai Utility shader, but you can also use the rest of the standard AOV's:

Beauty render	Ai Utility node rendered via 'ObjectID' AOV