Sphere Mapping in Environment map

When we implement the method of environment, we can select two kinds of textures, they are sphere and cube mapping.

Sphere mapping has the advantage of decreasing the memory of texture, but it only stores one direction patterns, so there will have some lost information while we look to another direction.

Cube mapping stores six direction patterns from the scene, so it has fully information to avoid the artifact, its disadvantage is it needs more memory and waste pixels because of some regions doesn't have any patterns, it is records with blank.

http://www.bluevoid.com/opengl/sig00/advanced00/notes/node184.html