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Physical Parameters

The BRDF depends on the wavelength of the light λ, as well as on several physical parameters of the surface including its z effective “roughness”, given by σ and τ, which specify the height and spacing of small statistical peaks on the surface, and its index of refraction n, which is a function of λ.

Examples of experimentally measured BRDF's are shown in Figure 3. Results are displayed for four different surfaces at a wavelength of λ = 0.55μm with incident light at θi = 60°. The red line denotes the incident direction. Photomicrographs of the surfaces are shown in Figure 4. The matte paint surfaces represent rough surfaces, whereas the aluminum surface is less rough but anisotropic, and the plastic surface is perfectly smooth. At a given wavelength, the BRDF depends on the size of the surface roughness, approaching specular reflection for smooth surfaces and diffuse reflection for rough surfaces.

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Figure 3: Experimentally measured BRDF's


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Figure 4: Surface photomicrographs corresponding to Figure 3

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