The problem of motion and shape estimation of a moving body with the aid of a monocular camera studied. It is shown that the estimation problem reduces to a specific parameter estimation of a perspective dynamical system. This reduction is independent of whether the data observed are points, lines, or curves on the image plane produced as a result of discontinuities in the brightness pattern. In this paper, many cases of the perspective parameter estimation problem is analyzed. The estimation procedure is carried out with the aid of a new 'realization theory for perspective system.