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The Fixed Viewpoint Constraint

  The fixed viewpoint constraint is a requirement that a catadioptric sensor only measure the intensity of light passing through a single point in 3-D space. The direction of the light passing through this point may vary, but that is all. In other words, the catadioptric sensor can only sample the 5-D plenoptic function [Adelson and Bergen, 1991] [Gortler et al., 1996] at a single point in 3-D space. The fixed 3-D point at which a catadioptric sensor samples the plenoptic function is known as the effective viewpoint.

Suppose we use a single conventional camera as the only sensing element and a single mirror as the only reflecting surface. If the camera is an ideal perspective camera and we ignore defocus blur, it can be modeled by the point through which the perspective projection is performed; i.e. the effective pinhole. Then, the fixed viewpoint constraint requires that each ray of light passing through the effective pinhole of the camera (which was reflected by the mirror) would have passed through the effective viewpoint if it had not been reflected by the mirror.


Simon Baker