Beyond the Lesson

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

Caustics provide additional realism in a rendered image by simulating the focusing of light on diffuse surfaces as a result of the light reflecting off specular surfaces or via the refraction of light through translucent surfaces.
Photons are used to determine the caustic effect in a scene via the creation of a photon map.
The brightness of the caustic is controlled by the Photon Intensity attribute.
The quality of the caustic effect is controlled by the number of photons emitted into the scene, the Accuracy, and the Radius attributes.
Multiple test renders are often required to achieve the desired final image.

Light sources for caustics

Point, spot, and mental ray area lights can be used as light types for caustics with the mental ray for Maya renderer. A Directional light does not work as a source for Caustics 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 Photon Map option in the Caustics and Global Illumination 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 Caustics. 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.