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The BRDF can be divided into three components:
ρ_{bd} = ρ_{bd,sp} + ρ_{bd,dd} + ρ_{bd,ud} | (3) |
where ρ_{bd,sp} gives the specular component, ρ_{bd,dd} gives the directional diffuse component, and ρ_{bd,ud} gives the uniform diffuse component. The components are shown schematically in Figure 5.
Figure 5: Components of the BRDF
We would like to examine the reflected radiance dI_{r}, which can be expressed as a product of the BRDF and the incident energy flux:
dI_{r} | = | ρ_{bd} • dE_{i} | |
= | (ρ_{bd,sp} + ρ_{bd,dd} + ρ_{bd,ud}) • dE_{i} | ||
= | dI_{r,sp} + dI_{r,dd} + dI_{r,ud} | (4) |
The general light reflection model that we will use [HE91] assumes a Gaussian, isotropic rough surface. The model is based on wave optics and accounts for diffraction and scattering effects. The model provides closed-form analytic expressions for the specular, directional diffuse, and uniform diffuse components of the BRDF. Any equations not given here are available in [HE91].
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