关键词: 凸壳, 点集, 对称轴, 信息完整, 信息不完整

Abstract: Based on the symmetry of an object, people can infer its structure and estimate its pose even if some parts of object are lost or occluded. This paper presented a new algorithm for detecting the symmetry axes of 2D point set. Firstly, convex hull of 2D point set can be obtained by convex hull algorithm. Secondly, for complete point set, its symmetry axes can be found through seeking the symmetry axes of convex hull. Thirdly, for incomplete point set, if the missing points are located inside the convex hull, point sets symmetry axes must be the symmetry axes of its convex hull; if the missing points include those points on the convex hull, perpendicular bisectors of convex hulls edges or angle bisectors of convex hull may be the symmetry axes of the point set. The method proposed in this paper can search the symmetry axes of object even though some points are lost or occluded. The experimental results demonstrate that the method has higher efficiency and better applicability.

Key words: convex hull, point set, symmetry axes, complete information, incomplete information