Shape Features of 2D Figures
The symmetry-diagram was originally defined for symmetry recognition. As a consequence it has been proven that the symmetry-diagram shows the unique shape property of the two-dimensional (2D) figures. The symmetry-diagram is different in the case of 2D figures having a different shape. It is very sensitive to the smallest change in the shape. The only exception for its applicability is the 2D figure having two or more concentric boundary loops.
P. J. Szabó and T. Berecz
Z. Szakál and I. Zsoldos, "Shape Features of 2D Figures", Materials Science Forum, Vol. 659, pp. 459-466, 2010