Prelighting stores the shading and lighting data from the rendered look of a mesh into the color per vertex data for the mesh. Prelighting is also referred to as light baking because it binds the information onto the object.
You can prelight the objects in your scene using Prelight features that use either the Maya software or mental ray for Maya renderers.
Prelighting objects in the scene lets a simpler display device (such as a video game console) show the objects as though they were shaded and illuminated without actually having the shading, lights, or textures, and without doing the rendering calculations in real time.
After prelighting a scene you can simplify it by removing the lights and shading, or simplify the shading networks, since the final shaded results are “baked on” the polygons.
Prelighting is also useful to export to a platform that does not support certain shading effects. For example, some graphic APIs only support a limited number of lights, and many platforms have a limited amount of texture memory available. If you prelight some lights and textures and bake their effects onto the geometry, they can then be removed from the scene.
Similarly, some platforms may be unable to fully achieve the effects available from Maya’s software rendering network. Prelighting removes the need to transfer the shading network functionality.
A sample can either be stored as color-per-vertex-per-face, or used to displace the position of a vertex.
If stored as a color-per-vertex-per-face color, RGB color and alpha (transparency) is stored. For displacement, the X,Y, Z coordinates of the vertex position changes. Since a sample contains four channels (RGBA), the displacement uses the luminance value of the color.