Algorithms for similarities between polygons are given in Arkin et al. (1991). It improves upon earlier studies where exact similarities were evaluated under affine transformations so that polygons with unequal vertices were classified as dissimilar. Furthermore, the algorithm gives a quantitative distance that's
a metric
invariant under affine transformations
easy to compute
matches intuitive notions of shape resemblances
E. M. Arkin, L. P. Chew, D. P. Huttenlocher, K. Kedem and J. S. B. Mitchell, "An efficiently computable metric for comparing polygonal shapes," in IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 13, no. 3, pp. 209-216, March 1991, doi: 10.1109/34.75509. [PDF1], [PDF2]
Algorithms for similarities between polygons are given in Arkin et al. (1991). It improves upon earlier studies where exact similarities were evaluated under affine transformations so that polygons with unequal vertices were classified as dissimilar. Furthermore, the algorithm gives a quantitative distance that's
E. M. Arkin, L. P. Chew, D. P. Huttenlocher, K. Kedem and J. S. B. Mitchell, "An efficiently computable metric for comparing polygonal shapes," in IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 13, no. 3, pp. 209-216, March 1991, doi: 10.1109/34.75509. [PDF1], [PDF2]