The problem of reconstruction can be stated as follows:

Given two photos (or planes) P and Q each containing N points (P={p1,p2, ...,pN} and Q={q1,q2, ...,qN}), is it possible to construct a set R of N points in space in such a way that P and Q are orthogonal projections of R?

We first present a method for recovering sets of points then we extend it to solve the more general case of polygon reconstruction. We illustrate the latter case with an interactive Java applet.

Finally, we derive a method for verifying photos of sets of points.