PxrAovLight is a handy utility light that allows a lighting artist to output a shot-specific AOV mask without needing to request one from the shading artists.
Light Linking with PxrAovLight
Use light linking to include/exclude pieces of geometry in the AOV. In this example, the PxrAovLight is "off" globally and "on" the tree in the scene. This linking set up creates creates a mask of the tree.
Light Filters and PxrAovLight
Because PxrAovLight is a "light", light linking and light filters can modify the output AOV. In this example, the PxrIntMultLightFilter is attached to PxrAovLight. The Light Filter is only linked to the tree trunk, resulting in a gray value for the tree trunk mask.
Defining the Output AOV
Use the PrmanOutputChannelDefine and RenderOutputDefine nodes to create the AOV to which PxrAovLight will write. These three parameters should all be the same: