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

TL;DR

This paper introduces a novel reduction technique for accurately rendering fluorescent materials in non-spectral engines, capturing color shifts and luminance effects by encoding re-radiation into a low-dimensional matrix aligned with the renderer's CMFs.

Contribution

The method provides a spectral-independent reduction approach that accurately models fluorescence effects in tristimulus rendering engines, including UV band addition.

Findings

Accurately matches spectral light transport for fluorescent materials

Handles non-visible ultraviolet band during light transport

Independent of specific CMF sets

Abstract

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.