Chapter 32. Creating Baked Textures and Normal Maps
3D games pose an interesting dilemma—creating interactive scenes that are displayed in real time with the highest quality graphics. To achieve this, game developers use a number of tricks designed to speed up the rendering time. One of these tricks is pre-rendering textures that include all the lighting information and applying these pre-rendered textures as texture maps. This allows advanced lighting solutions such as global illumination to be included within a game without requiring extra time to render such a complex solution. The process of applying pre-rendered textures as maps is called baking a texture.
Rendering textures is a significant part of the rendering process, and baking a texture doesn't remove this step; it simply completes the step beforehand, so that the game engine doesn't need to do the texture calculations.
Another common efficiency trick is to use normal maps. Normal maps calculate the lighting results used to light small details that stick out from the surface of an object. These details are then re-created using a normal map that is applied back onto a simplified version of the object. The normal map allows these details to be simulated without the extra polygons used to create them. By allowing simple base objects to have details such as bolts and rivets without the extra polygons, the objects can be redrawn quickly without ...