Non-Orthogonal Reduction for Rendering Fluorescent Materials in Non-Spectral Engines

We propose a method to accurately handle fluorescence in a non-spectral (\eg, tristimulus) rendering engine, showcasing color-shifting and increased luminance effects. Core to our method is a principled reduction technique that encodes the re-radiation into a low-dimensional matrix working in the space of the renderer's Color Matching Functions (CMFs). Our process is independent of a specific CMF set and allows for the addition of a non-visible ultraviolet band during light transport. Our representation visually matches full spectral light transport for measured fluorescent materials even for challenging illuminants.