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Parameter Interpolation and Normalization

Phong shading implies that for every pixel, the vectors being involved in the shading equation are interpolated, normalized and their dot product computed. Without normalization the highlights get lost across a polygon. To be general, the interpolation of two vectors $ \vec{v}_{1}$ and $ \vec{v}_{2}$ is considered. This can be any vectors: the light vector $ \vec{L}$, viewing vector $ \vec{V}$ or normal vector $ \vec{N}$.


Gerald Schröcker 2002-03-21