关键词: 缓解阀盖, 匹配, 有向线段, 成对几何直方图

Abstract: For the missing faults of release valve bonnets in freight cars, an image matching algorithm was proposed herein based on contour reconstructed by oriented line segment and pairwise geometrical histogram. Firstly, the location of initial sampling point was defined by maximum chord length and polar radius, then the contour was dynamically and hierarchically sampled according to an evaluation mechanism of local curvatures. Then adjacent sample points were lined in counter-clockwise order, oriented relative angles and normalized equivalent distances between pairwise oriented line segment were calculated as the dual descriptors, which were counted into the two dimensional histogram. Finally the similarity between histograms was measured by Bhattacharyya distance. The experimental results show that the algorithm may keep robust under the circumstances of rotations, scales and translations, meanwhile the detection efficiency is also well ensured, which may satisfy the instantaneity of the detection on freight cars.

Key words: release valve bonnet, matching, oriented line segment, pairwise geometrical histogram