This talk details the approximation of dynamic global illumination used in FarCry 3. The talk is divided in two parts - first, an overview of the theory and offline pre-computation, followed by real-time rendering implementation and shading details.

We use a sparse volume of radiance transfer probes, with each probe storing spherical harmonics coefficient matrices. We can relight the probes on the fly, thus supporting illumination under time of day changes, as well as local lighting such as muzzle flashes and explosions. Shading using the relit probes is done on the GPU in screen space.

We use a hybrid CPU / GPU implementation to ensure the system runs well on the current generation of consoles. Our implementation is efficient both memory- and performance-wise. We will provide detailed performance statistics, as well as code snippets to illustrate the internals of the system.