This paper assesses the question, given a arbitrary point in P3, can it be reconstructed by a given camera orbit? We show that a solution to this problem can be found by intersecting the frustrums of the cameras in the sequence creating a polyhedron that bounds the area in P3 observed by all cameras. For a projective set of cameras this can be considered as an expansion of the chetral inequalities. We also show an exception to this basic principle is encounted when the point in P3 is occluded. Thus giving a weak condition for occlusion of an arbitrary point in P3.
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