Projective translations and affine stereo calibration

This paper investigates the structure of projective translations-rigid translations expressed as homographies in projective space. A seven parameter representation is proposed, which explicitly represents the geometric entities constraining and defining the translation. A practical algebraic method for estimating these parameters is developed. It provides affine calibration of a stereo rig, determines the translation axis, and allows projective translations to be composed. The practical effectiveness of the calibration is evaluated on synthetic and real image data.