Below is an example of a basic scene used to demonstrate the usage of user Cryptomatte AOVs.

• User Data (named userid) is applied to each object that is required a user AOV. You can define any custom name for the objects in the userid parameter, they are used as the IDs in the custom user AOV.

• Add an attribute to the robot's shape geometry node (Attributes > Add Attribute). Type 'mtoa_constant_userid' in the field next to 'Long name'. Note that you must use lower case letters. Capital letters will not work. Change the Data Type to String.

• Create a Custom AOV called crypto_userid.

_{crypto_userid custom AOV}

• Create a cryptomatte shader and under AOV name, enter crypto_userid.
• Set userid as the Source User Data in the shader.

_{Cryptomatte shader with crypto_userid AOV name and userid as Source User Data}

• Connect the Cryptomatte shader to the Custom AOV -> Shader of the AOV.

• Render the scene. You should be able to view the crypto_userid AOV.