Dijkstra's in Disguise
> Path tracing integrals are fairly expensive because states and actions are continuous and each bounce requires ray-intersecting a geometric data structure. What if we do light transport simulations on a point cloud with a precomputed visibility matrix between all points, and use that as an approximation for irradiance caching / final-gather?A crude variation on this is often used in games, known as "light probes". You precompute the light transport simulation on a subset of points in the scene (manually placed by artists), and lighting for dynamic objects simply lerps between the nearest light probes.