The perspective view of three points

The perspective view of three noncollinear points whose image-to-object correspondence is known is studied. Such measurements are known to be ambiguous, resulting in as many as four possible solutions to the perspective three-point problem. Although there can be four solutions, it is quite often the case that there are triangle configurations that cause one, two, three, or four solutions. The results also provide a justification for the common wisdom that there are usually two solutions.>