Radiance Caching for Real-Time Global Illumination

Daniel Wright explains the radiance caching and final gather techniques used for real-time global illumination in Unreal Engine 5.

This talk will present an efficient and high-quality Final Gather for fully dynamic Global Illumination with ray tracing, targeted at next generation consoles and shipping in Unreal Engine 5. Part of the SIGGRAPH 2021 Advances in Real-Time Rendering in Games course ( advances.realtimerendering.com/). Hardware Ray Tracing provides a new and powerful tool for real-time graphics, but current hardware can barely afford 1 ray per pixel for diffuse indirect, while Global Illumination needs hundreds of effective samples for high quality indoor lighting. Existing approaches that rely on Irradiance Fields cannot scale up in quality, while approaches relying on a Screen Space denoiser have exorbitant costs at high resolutions. This talk will present practical applications of Radiance Caching along with effective techniques to reduce noise and leaking. Bio: Daniel Wright is an Engineering Fellow in graphics at Epic Games, and Technical Director of the 'Lumen' dynamic Global Illumination and Reflections system in Unreal Engine 5. Prior to that, he developed lighting and shadowing techniques for Unreal Engine 3 and 4 which shipped in Gears of War, Fortnite and a multitude of games licensing Unreal Engine technology. Daniel's main passion is real-time Global Illumination.