Interactive Light Map and Irradiance Volume Preview in Frostbite

This chapter presents the real-time global illumination (GI) preview system available in the Frostbite engine. Our approach is based on Monte Carlo path tracing running on the GPU, built using the DirectX Raytracing (DXR) API. We present an approach to updating light maps and irradiance volumes in real time according to elements constituting a scene. Methods to accelerate these updates, such as view prioritization and irradiance caching, are also described. A light map denoiser is used to always present a pleasing image on screen. This solution allows artists to visualize the result of their edits, progressively refined on screen, rather than waiting minutes to hours for the final result using the previous CPUbased GI solver. Even if the GI solution being refined in real time on screen has not converged after a few seconds, it is enough for artists to get an idea of the final look and assess the scene quality. It enables them to iterate faster and so achieve a higher-quality scene lighting setup.