PT Journal
AU Josep Llados
   Horst Bunke
   Enric Marti
TI Finding rotational symmetries by cyclic string matching
SO Pattern recognition letters
JI PRL
PY 1997
BP 1435
EP 1442
VL 18
IS 14
DI 10.1016/S0167-8655(97)00144-X
DE Rotational symmetry; Reflectional symmetry; String matching
AB Symmetry is an important shape feature. In this paper, a simple and fast method to detect perfect and distorted rotational symmetries of 2D objects is described. The boundary of a shape is polygonally approximated and represented as a string. Rotational symmetries are found by cyclic string matching between two identical copies of the shape string. The set of minimum cost edit sequences that transform the shape string to a cyclically shifted version of itself define the rotational symmetry and its order. Finally, a modification of the algorithm is proposed to detect reflectional symmetries. Some experimental results are presented to show the reliability of the proposed algorithm
ER