The four remaining material types are for more advanced purposes, so this section just gives you an overview of what they're used for. The Layered Shader lets you combine several materials to create a more complex material. For example, if you want chrome polka dots on a wood surface, you can simply use a polka dot mask in a Layered Shader and then bring in your already-completed chrome and wood materials.
The Shading Map material is primarily designed to let you get a "cel" look in 3D, like typical animated cartoons. You can use this shader for a 2D painted-in look rather than smoothly shaded 3D. The Ramp Shader, new in version 4.5, is a material designed to make it easier to create and control a cel or illustration-style look. The Shading Map material can be used for special effects. Its prior application for cel style shading is now taken over by the Ramp Shader.
The Surface Shader is used when you want to control a material's color, transparency, and/or glow with something else in Maya. For example, you could link color to any object's XYZ position, and the material would then change colors as that object moved around the scene.
The Use Background shader applies the background (image plane or environment) color to the surface that it has been applied to. This allows you, for example, to have shadows cast on an image of a road used as an image plane. This shader type can also be used to cut a "hole" in the image's alpha channel where objects with the material appear. This material is useful for a technique in which separate rendered images are combined in a compositing program to create the final results (for more information, see Chapter 15, "Your Next Steps: Efficiency and Artistry"). CG artists usually do this to divide a large, complex animation into more manageable parts or to combine 3D animation with photographed/filmed live action.