Is There Anything Comparable to Spherical Harmonics But Simpler?

Speakers: Chi Sing Leung, Tien-Tsin Wong

Track: Programming

Format: Lecture

Experience Level: Intermediate

Description: This lecture introduces a computationally more efficient, mathematically simpler, and visually identical substitute to spherical harmonics (SH). It is spherical radial basis function (SRBF). It represents lighting including soft shadow, caustics, interreflection, HDR environment map, and other global illumination like effects. It naturally supports both local illumination (point and directional sources) as well as lighting under distant environment (integration of lighting contributions over a spherical environment). The lecture covers the underlying mathematics (which shows simplicity), describes its implementation (which exhibits its computational efficiency), and demonstrates the visual results (which shows its comparability). We also present the mathematics for obtaining the noise-proof SRBF coefficients, so that compression (that introduces quantization noises) can be applied on them to achieve a compact solution for sophisticated lighting effects. A set of tools and hacks is provided and explained to achieve various lighting effects and real-time performance. It can be shown that all lighting effects by SH are achievable with SRBF, including the tricky rotation.

Idea Takeaway: The presentation delivers the underlying mathematics, implementation details/experiences/tricks, and demonstrations of this novel SRBF lighting framework. A SRBF toolkit with source code is also provided and detailed.

Intended Audience: Rendering engine programmers and hackers who are looking for efficient and simpler implementation of realistic lighting effects.