Camera self-calibration: a new approach for solving the modulus constraint
In this paper, the modulus constraint is used to retrieve the scale factors that are responsible for the nonlinearity of Kruppa's equations. In the case of constant intrinsic parameters, each pair of images identifies a pair of 3D points at infinity whose coordinates are expressed in terms of the scale factors we are looking for. By enforcing the coplanarity constraint on these points, a set of quintic bivariate equations is obtained for each triplet of images. Once the scale factors are calculated, the problems of retrieving the plane at infinity and solving Kruppa's equations become straightforward and linear.