Detection and localisation of reflectional and rotational symmetry under weak perspective projection

摘要

In this paper, a novel method is proposed for detecting and recovering the pose of a reflectional and rotational symmetry from a single weak perspective image. In our paradigm, an effective and novel Hough-based approach is proposed for extracting skew symmetry axes from edge contours. A refinement algorithm is developed for verifying and pruning away the implausible and spurious hypothesised symmetry axes. For each of the detected skew symmetry axes and its corresponding skew angle, a mathematical formulation is devised for evaluating the geometric relationships between an orthogonal junction formed by a symmetry axis and its perpendicular axis in an original plane and its corresponding skew angle in an image plane. The derived geometric formulation is integrated into an effective voting scheme for estimating the projective parameters of a reflectionally and rotationally symmetric planar shape using the information of the plausible skew symmetry axes. Experimental results are presented to verify the computational performance of the proposed paradigm. The practical significance and generality of the proposed method are manifold.