Path Verification for Dynamic Indirect Illumination

In this paper we present a technique that improves rendering performance for real-time ith ray in the presence of dynamic lights and objects. In particular we verify photon paths from the previous frame against dynamic objects in the current frame, and show how most photon paths are still valid. When using area lights, we use a data structure to store light distribution that tracks light paths allowing to be reused when the light source is moving in the scene. We also show that by reusing paths when the error in the reflected energy is below a threshold valuing a screen space photon splatting rendering engine. By reusing photon paths and applying our error threshold, our method can reduce the number of rays traced by up to 5×, and improve performance by up to 2×.