In computer graphics, sphere mapping (or spherical environment mapping) is a type of reflection mapping that approximates reflective surfaces by considering the environment to be an infinitely far-away spherical wall.
This environment is stored as a texture depicting what a mirrored sphere[further explanation needed] would look like if it were placed into the environment, using an orthographic projection (as opposed to one with perspective).
This texture contains reflective data for the entire environment, except for the spot directly behind the sphere.
(For one example of such an object, see Escher's drawing Hand with Reflecting Sphere.)
The result appears like the environment is reflected in the surface of the object that is being rendered.
However, we are given the reverse task (a normal for which we need to produce a texture map coordinate).