4 ms·

Photon mapping? As in can render diffraction?

• magicalhippo 7y ago
  Simplified, photon mapping is a technique where you shoot rays from the light sources and then record the hits on geometry. Name comes from pretending you're tracing a photon bouncing around. Then, when doing the regular ray/path tracing, at each intersection of the camera-ray, you see if the intersection location is near any of the light-ray hits. If so, add in some contribution from the light-ray hits. This avoids you having to explicitly check each light at each intersection point, saving you quite a number of visibility tests. Also, due to the smoothing kernel used when the "photon contributions" are added up, it leads to low-frequency noise rather than high-frequency noise that is normal in regular path tracing. This is especially noticeable when caustics are involved. A nice introduction to the technique can be found here: https://web.cs.wpi.edu/~emmanuel/courses/cs563/write_ups/zackw/photon_mapping/PhotonMapping.html https://web.cs.wpi.edu/~emmanuel/courses/cs563/write_ups/zac...