What Are Spherical Environment Maps?

Spherical environment maps, or "sphere maps," are special textures that contain an image of the scene surrounding an object, or the lighting effects around the object. Unlike cubic environment maps, sphere maps don't directly represent an object's surroundings. The teapot image in the What Is Environment Mapping? topic shows the reflection effects you can achieve with sphere mapping.

A sphere map is a 2-D representation of the full 360 degree view of the scene surrounding of an object, as if taken through a fish-eye lens. The following is the sphere map in use by the Spheremap sample (C++).