Simulating Diffuse Interactions

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Simulating Diffuse Interactions

Diffuse light reflecting across a surface is easily simulated using photon mapping because the photon map is constructed only by diffuse interactions. Figures 14.1 through 14.3 show some diffuse interactions that were rendered using photon mapping. Figure 14.1 shows an example of diffuse interaction and indirect illumination on a desk model with a pyramid-looking object on top of the desk. The scene includes one light source that casts a shadow for the pyramid object.

Figure 14.1. An example of diffuse interaction and indirect illumination in a desk model with a pyramid object using photon mapping.

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Figure 14.2. An example of diffuse interaction and indirect illumination in a desk model with a cup, box, and two light sources using photon mapping.

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Figure 14.3. An example of diffuse interaction and indirect illumination in a textured desk model with a sphere, cup, box, and two light sources using photon mapping.

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Figure 14.2 shows a scene with two lights that cast two shadows per object. If you look closely, you actually see the penumbra in the shadows.

Figure 14.3 shows diffuse interaction and indirect illumination on a textured desk model with a sphere, cup, and box. This scene has two lights that cast multiple shadows reflected on the desk from the three objects.

Triangles require a relatively low number of photons to look realistic, whereas spheres, due to their curved nature, require a minimum of 10,000 photons. Figure 14.4 shows a comparison of a photon and a sphere.

Figure 14.4. Sphere com parison (1,000 versus 10,000 photons).

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Focus On Photon Mapping
Focus On Photon Mapping (Premier Press Game Development)
ISBN: 1592000088
EAN: 2147483647
Year: 2005
Pages: 128
Authors: Marlon John

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