Baking illumination and color

In a typical scene, you shade, texture, and light objects to create the look you want, then you render. You can instead pre-render materials, textures and illumination in a process called baking (by render experts) or prelighting (by modeling experts).

Baking effectively freezes the illumination (and shadow and surface color, if wanted) of baked objects into an image file (if you bake to textures) or data (if you bake to vertices) that you can later apply to objects.

After you bake objects and apply the prerendered illumination to objects, you can simplify the scene by removing lights, materials, and textures (shading networks). Instead of computing illumination at render time, the renderer instead obtains it quickly from the applied file image or data that is produced (depending on what you bake to -- textures or vertices).

When to bake objects

• To accelerate time and processor-intensive renders, particularly for complex shading networks or if global illumination features are involved.
• To optimize renders for use on simpler display devices (such as a console game rendering engine).
• To achieve lighting effects that would otherwise be difficult to achieve in other ways.
• 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 bake the effects of the lights and textures onto the geometry, the lights and textures can then be removed from the scene.
  Note: In Maya, baking is called Convert to File texture. See Convert a texture or shading network to a File Texture.