Real-Time Image-Based Lighting of Dynamic Scenes with Moment Soft Shadow Mapping

Casting shadows in dynamic scenes under complex illumination is a challenging problem, since no precomputation can be applied. The illumination is provided in form of a light probe, which potentially changes every frame. We propose a method for generating area lights from the light probe, built upon a median cut algorithm for light probe sampling. The shadows from the area lights are efficiently computed by moment soft shadow mapping, which has a lower memory footprint than other techniques. In this process very large area lights are utilized, pushing the limits of moment soft shadow mapping. We demonstrate the use of 6 instead of 4 moments in moment soft shadow mapping, which drastically increases the quality of the shadows for large area lights. We also present some other modifications, in order to improve the resulting shadows. We implemented the algorithm for generating area lights in compute shaders and demonstrate the sampling of animated light probes on the GPU and lighting of a dynamic scene in real time.