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Creating diffuse light that's reflecting to other surfaces in the scene is easily accomplished by using photon mapping. Remember, in the photon-tracing process, you traced the diffused energy being reflected to other surfaces in the scene. See Figure 14.5 for an example.
This process is the same as in radiosity because the same color bleeding effects are simulated. For example, if a white photon reflects a red wall, the reflected photon is red. See Figure 14.6 for an example.
The problem with using too few photons in diffuse reflection for color-bleeding effects is that it causes blotchy and discolored results. To remedy this problem, a large number of photons are to be used to blend the discoloration. A value of at least 10,000+ photons per object should be used to render diffuse reflected energy. Figure 14.7 shows the difference between 1,000 photons and 10,000 photons per object.
NOTE
NOTE
It isn't a good idea to simulate specular (mirror) reflections in pho- ton mapping.The photon map can grow tremendously in size due to the large number of photons required to reflect light on a mir- ror's surface.
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