Invariant Properties of the Motion Parallax Field Due to the Movement of Rigid Bodies Relative to an Observer

Abstract It is shown that the time-change of the natural perspective, due to the movement of rigid bodies relative to an observer, conveys information about geometrical properties of the moving surfaces. Certain differential properties of the dynamic perspective are shown to be conserved. These properties are related to determinants of the shape of the surface elements of the moving bodies, as for instance the sign of the gaussian curvature, the asymptotic curves and the future contours. A kinematic analysis of the motion parallax field shows that the type of parallax field is related to the slant of the surface relative to the observer. The theory is of possible significance to visual kinesthesis.