Real-time all-frequency global illumination with radiance caching

Abstract

Global illumination (GI) plays a crucial role in rendering realistic results for virtual exhibitions, such as virtual car exhibitions. These scenarios usually include all-frequency bidirectional reflectance distribution functions (BRDFs), although their geometries and light configurations may be static. Rendering all-frequency BRDFs in real time remains challenging due to the complex light transport. Existing approaches, including precomputed radiance transfer, light probes, and the most recent path-tracing-based approaches (ReSTIR PT), cannot satisfy both quality and performance requirements simultaneously. Herein, we propose a practical hybrid global illumination approach that combines ray tracing and cached GI by caching the incoming radiance with wavelets. Our approach can produce results close to those of offline renderers at the cost of only approximately 17 ms at runtime and is robust over all-frequency BRDFs. Our approach is designed for applications involving static lighting and geometries, such as virtual exhibitions.