Accurate real-time rendering under complex illumination remains a central challenge in computer graphics, particularly for interactive applications such as gaming. While image-based lighting (IBL) frameworks and the widely used SplitSum approximation enable efficient rendering of specular materials, they rely on simplifying assumptions that introduce artifacts, especially at grazing angles. In this work, we present a novel rendering scheme that improves the approximation of specular reflectance by leveraging spherical harmonics (SH) for low-frequency illumination. For the high-frequency components, we retain the efficiency of the SplitSum method. Our approach decomposes Env. Maps into frequency bands and introduces an analytic SH-based solution to the rendering equation in a unique local shading frame (ULSF), allowing BRDF representations to be efficiently stored in scene-independent lookup tables.We implement our method in Unity and OpenGL, demonstrating improved accuracy over prior approaches, including reduced light leakage and more faithful rendering of rough materials, while maintaining real-time performance with only marginal overhead compared to SplitSum
Yam Kushinsky is a PhD student at the Weizmann Institute of Science, advised by Prof. Ronen Basri. His research focuses on inverse rendering, Gaussian splatting, and real-time rendering — with a particular interest in recovering geometry, materials, and lighting from images.
Prior to his PhD, Yam worked for five years as an algorithms developer at Common Ground, where he focused on inverse rendering for human avatars. He holds a Bachelor’s degree in Physics and Electrical Engineering, and a Master’s degree in Applied Mathematics from the Weizmann Institute, where he studied convex optimization under the supervision of Prof. Yaron Lipman.