Equation 5.3 is not completely determined by the epipolar geometry (i.e. and ), but has 4 more degrees of freedom (i.e. ). determines the position of the reference plane (i.e. the plane at infinity in an affine or metric frame) and determines the global scale of the reconstruction. The parameter can simply be put to one or alternatively the baseline between the two initial views can be scaled to one. In [7] it was proposed to set the coefficient of to ensure a quasi-Euclidean frame, to avoid too large projective distortions. This was needed because not all parts of the algorithms where strictly projective. For the structure and motion approach proposed in this paper can be arbitrarily set, e.g. .