Recognizing algebraic surfaces from their outlines

The author shows that the projective invariants of an algebraic surface can be computed from the outline of that surface in a perspective view using an uncalibrated camera, by showing that an outline completely determines the projective geometry of an algebraic surface. A single perspective view of a generic algebraic surface of degree three or greater uniquely determines the projective geometry of the surface. The result holds for an unknown focal point, and an uncalibrated camera. The projective ambiguity is not improved by using a calibrated camera