Normal Storage

Aras Pranckevičius has recently done a very complete post on different methods for compact normal storage.

'obvious' approaches like storing X&Y and reconstructing Z, or using spherical coordinates don't perform very well, on the other hand Stereographic Projection and Sphere Mapping apparently perform very well. Just goes to show you that even having the right idea (spherical coordinates) won't necessarily work well unless you find the right encoding.