Directional lightmap encoding insights
Peter‐Pike Sloan, Ari Silvennoinen · 2018
Lightmaps that respond to normal mapping are commonly used in video games. This short paper describes a novel parameterization of a standard lightmap encoding, Ambient Highlight Direction (AHD) --- a model for directional irradiance consisting of ambient and directional light --- that eliminates common interpolation artifacts. It also describes a technique for fitting the AHD model to lighting represented as spherical harmonics, where the unknown model parameters are solved in the null space of the constraint that irradiance is preserved.