PARAPERSPECTIVE AFFINE

It is shown that the set of all paraperspective images with arbitrary reference point and the set of all affine images of a 3-D object are i dentical. Consequently, all uncalibrated paraperspective images of an object can be constructed from a 3-D model of the object by applying a n affine transformation to the model, and every affine image of the ob ject represents some uncalibrated paraperspective image of the object. It follows that the paraperspective images of an object can be expres sed as linear combinations of any two non-degenerate images of the obj ect. When the image position of the reference point is given the param eters of the affine transformation (and, likewise, the coefficients of the linear combinations) satisfy two quadratic constraints. Conversel y, when the values of parameters are given the image position of the r eference point is determined by solving a bi-quadratic equation.