Introduction to Spherical Harmonics for Graphics Programmers
Summary
Introduction to Spherical Harmonics for Graphics Programmers explains how SH form an orthonormal basis on the sphere and how to project lighting, radiance, and irradiance into SH coefficients. It provides practical JS code samples for evaluating SH basis up to degree 3, case studies on cubemap projection and irradiance, plus discussion of deringing and windowing to suppress ringing artifacts. The article also covers real-valued SH, coordinate conventions, and links to foundational papers.