Appendix A. Normal Mapping in Maya
A TECHNIQUE USED in many of today's games is normal mapping. This is a method of making a low-polygon object or character appear to have more surface detail than it actually has, by collecting intricate lighting detail from a high-polygon version and applying it to the normals of the low one. Normals are the vectors (direction) a surface is facing.
Actually an application of bump mapping, normal mapping also works from a bitmap image. Normal maps are different from bump maps, however, in terms of the information they store. Bump maps work off a grayscale image that only registers changes in height; a normal map uses an RGB image, which contains enough information to store not only height but direction as well.
Red is the direction across the object, from left to right. Green goes from top to bottom, and the amount of blue dictates the height. The stronger the color, the more that normal faces in that specific direction.
Normal maps are becoming a key part of game development, so it's important to have some experience with creating them in Maya.