Figure 3

Symmetric Closest Point algorithm description. The symmetric closest point algorithm finds correspondence between the points in two contours by first finding the set of symmetric closest points, then using that set to find remaining point correspondence. In the left illustration above, P1 and P2 are not symmetric closest points; in the right illustration, P1 and P2 are symmetric closest points. To find the symmetric closest points for each point P1, the nearest neighbor P2 on contour c2 is found, and for each P2, the nearest neighbor P1' on C1 is found. If P1 = P1', then P1 and P2 are considered symmetric closest points.