Radiance Caching with On-Surface Caches for Real-Time Global Illumination

Achieving global illumination is crucial for delivering realistic lighting in real-time rendering applications. Despite recent advancements in hardware ray tracing, the computational demands of full path tracing remain largely impractical for real-world production scenarios. We introduce a novel two-level radiance caching system that exclusively utilizes on-surface caches, diverging from conventional approaches that combine screen-space and world-space caches. Unlike previous texture space techniques, which mostly prioritize closely matching the resolution to screen space to minimize artifacts, our focus is on achieving optimal visual quality with minimal texture space resolutions. By caching directional radiance information on both primary and secondary hits, our approach delivers high-quality renderings of global illumination while being computationally efficient. Overall, this leads to an up to 5% to 10% improvement in both speed and quality compared to other state-of-the-art approaches. Our proposed method is versatile, handling not only diffuse global illumination but also addressing (glossy) reflections. Furthermore, our approach is well-suited for multi-viewer rendering, as the utilization of on-surface caches enables information sharing among different viewers, making it applicable to cloud-native rendering environments.