Check out the intro video here https://simplymaya.com/autodesk-maya-...ay/?tut_id=307

If you find yourself rendering over and over again for hours at a time, this is the tutorial for you. In this tutorial we'll attempt to demystify mental rays render pass system paying special attention to the mia_material_x and it's outputs.

We'll also look at common uses for render layers such as ambient occlusion and depth. We'll show you how to split your image apart to achieve an almost material level control in post. We'll delve into complex masking with pass contribution maps as well as simple masks using custom color passes.

We'll achieve control of the individual lights in the scene in post saving you tons of time.

By the end of this course you should have total control of what comes out of mental ray, giving you back control and more importantly saving you time.

We will be using nuke in this course for the post production work all scene files will be included.

https://simplymaya.com/autodesk-maya-...ay/?tut_id=307