Photon Mapping

The idea behind Photon mapping is to shoot out photons from the light source and store the location, power, and direction when they hit something. Then you do the conventional raytracing but when you hit an object you collect the photons within a certain distance of that point to determine the intensity at that point. Often there are multiple maps used in photon mapping such as 1 for the global illumination and 1 for caustics. For my Photon mapping I used a caustic map and a global map. I also only used the global map for indirect lighting and but I used the caustic map and direct lighting method to determine the direct light.

Images

Pretty simple glass ball in a room

Here is a glass Buddha notice the caustics and the sharp edges I didn’t really like this

one but it shows off photon mapping pretty well so I thought I would post it anyway

Another glass Buddha I tweaked with the area of the search for photons and

the number to find, I think this one looks better then the first one.

This is the caustic photon map and the global map combined. Notice how the Buddha has no photons on it since its specular