A New Method of 3-D Motion Analysis Using a Concept of Projective Geometry

This paper describes a method of interpreting three dimensional motion of an object by making use of rigidity assumption and orientation of its edge. We employ a vanishing point to determine the orientation. We propose a new idea of using cross ratio, i.e. one of the most fundamental concepts in projective geometry to find a vanishing point of a line. This allows to calculate the location of a vanishing point with a known sequence of points on it without another parallel line required by the conventional method.