Rendering menu > Render > Render Scene dialog > Processing panel
Main toolbar > Render Scene button > Render Scene dialog > Processing panel
Note: The Processing panel appears only when the mental ray renderer is the currently active renderer.
The Processing panel is an additional Render Scene dialog panel. It appears only when the mental ray renderer is active, and its controls relate to managing how the renderer operates. It also lets you generate diagnostic renderings in pseudo color.

The Processing panel contains three rollouts:
Translator Options Rollout (mental ray Renderer)