Beyond the Lesson

In this lesson you were introduced to the Global Illumination features provided by the mental ray® for Maya® renderer. You learned that:

The mental ray for Maya renderer provides a feature that simulates indirect illumination in the Maya scene called Global Illumination.
Global Illumination allows you to achieve realistic lighting effects for objects and areas of the scene that do not receive direct lighting.
Photons are used to measure the Global Illumination of the scene via the creation of a photon map.
The brightness of the Global Illumination in a scene is controlled by the Photon Intensity.
The quality of the Global Illumination effect is dependent on the number of photons emitted into the scene, the Accuracy, and the Radius attribute settings.
Multiple test renders are often required to achieve the desired final image.

Light sources for Global Illumination

Point, spot, and mental ray area lights can be used as light types for Global Illumination with the mental ray for Maya renderer. A Directional light does not work as a source for Global Illumination because this light type does not have a defined point of origin (that is, the rays emit in a parallel manner).

Photon maps

You can visualize the photon mapping that occurs at the beginning of the rendering process provided you turn on the Enable Map Visualizer option in the Caustics and Global Illumination > Photon Tracing section of the Render Settings window. To view a visualization of the photon mapping, select Window > Rendering Editors > mental ray > Map Visualizer.

Visualizing the photon mapping can aid in determining whether the coverage and density of photons for the scene is appropriate for the resulting final image.

By default, the mental ray for Maya renderer rebuilds the photon map each time you render a scene using Global Illumination. If you are rendering a scene containing camera animation in which the objects and lights remain static, or rendering several iterations of a single image, you may consider turning off the Rebuild Photon Map setting in order to reduce the rendering times for each frame.