every object in our database is represented by the x and y coordinates of its boundary points. the arc length, we re-sample the boundary and represent by 200 equally distant points. length, we re-sample varies from 400 to 1200 for these images. to normalize the arc length, we re-sample the boundary and represent it by 200 equally distant distant distant points, therefore, the perimeter of all boundaries will the same and every point on the boundary has a correspondence in the horizontal axis of the css image (figure2)