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. In this example, we'll break down a common request...getting a refraction AOV for a character's eye (sclera or iris inside a cornea).

To simplify it further, we'll demonstrate it with a red sphere inside a glass sphere.

Maya and RIB file

Download a Maya file or inspect a RIB file for this example:

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" for the eye in the scene.  This linking setup creates a mask of the red sphere inside the refractive glass. 

Defining the Output AOV

Once you set an AOV Name in the PxrAOVLight attributes, use the Render Settings AOVs tab to define a new display to which PxrAovLight will write.

Make sure the names match, like so:

Light Filters and PxrAovLight

Because PxrAovLight is a "light", light linking and light filters can modify the output AOV.