 If this is not the case which, for example, typically is the case if formula_2 has been estimated from real (and noisy) image data, it has to be assumed that it approximately satisfy the internal constraints.The vector formula_103 is then chosen as right singular vector of formula_2 corresponding to the smallest singular value.The problem to be solved there is how to compute formula_121 given corresponding normalized image coordinates formula_122 and formula_123.