3Ds Max Rendering with Mental Ray & Final Gather

Mental Ray is a renderer that calculate diffuse reflections unlike another renderers. In the reality, diffuse relfrections are effects of the reflected light that bounces of diffuse surfaces. Mental Ray is near the real because it simulate these diffuse reflections with a method called 'Final Gather'. After theory we can start with pratice.

This render need Mental Ray selected (by default) in the Assign Render subsection (under Render Window -> Common).

For the first step you need to remove all lights from the scene and add only a Omni for example. Set multiplier of the light to a custom value (1.0 , 1.2 , ...).

Nextly in the 'Render Window' go to 'Indirect Illumination' tab and check 'Final Gather' under 'Basic' subsection.

Now you are ready to render. If you want Shadows you can activate Ray 'Traced Shadows' from Omni; instead if you want to change rendering speed you can set, under 'Indirect Illumination' tab, 'Rays per FG Points' to a small value.

You can change quality of sampling in 'Renderer' tab under 'Sampling Quality' subsection.

Below an example with Final Gather, Omni Light and Geospheare as sky: