A landmark-based approach of shape dissimilarity

A general contour-oriented shape dissimilarity measure is shown to give unreliable answers due to the arc-length parametrization. Local differences in curve-length due to biological variation cause mismatches in the contour-representations. In many applications all objects to be compared have a basic model in common, which can often be found by the use of landmarks. In the application shown here, which was a comparison of flowers of potato-species (Solanum spp), the basic model was characterized by the five petal tips, which should be at equal intervals. By restoring the basic model for each contour before calculating the dissimilarity measures, the errors of the arc-length parametrization were considerably reduced. This resulted in more reliable and faster dissimilarity measures for the application of potato flowers