I am looking for documentation, or code or an example of how to extract spherical harmonics coefficients from a light-probe HDR file.
I currently use a HDR cube-map as a skybox in my game, but would like the SH coefficient to do some relighting.
ZbuffeR:
Spherical harmonics is a way of storing/compressing data/functions that are defined on the surface of a sphere, by storing them as being made up of a sum of spherical harmonic functions. It’s simply a mathematical object and it is not directly related to any kind of lighting.
PRT is the actual à la mode lighting system using SH to store light information in all direction around an object.