Polygon Recognition and Symmetry Detection
  We introduce an approach based on moving frames for polygon recognition and symmetry detection. We present detailed algorithms for recognition of polygons modulo the special Euclidean, Euclidean, equi-affine, skewed-affine and similarity Lie groups, and explain the procedure for a generic Lie group. The time complexity of our algorithms is linear in the number of vertices and they are noise resistant. The signatures used allow the detection of partial as well as approximate equivalences. Our method is a particular case of a general method for curve recognition modulo Lie group action. 
Mireille Boutin