Ran Ben Avraham discusses two methods of illumination in Maya using Mental Ray, comparing Global Illumination and Photometric Lighting providing a great look at the two less commonly used methods for rendering with mental ray.

In this tutorial I would like to explore two less commonly used methods of illuminating our scenes, Global Illumination and photometric lighting

Using the Mental Ray mia_Photometric light for one illumination models, and GI for the other, Ran Ben Avraham compares the two illumination methods in Maya, and shows the pros and cons of using both by using the same base scene for illumination and rendering. Check out the tutorial for comparing Global Illumination vs Photometric Lighting in Maya here.