Visual detection of regular hexagon

A vision detection method based on geometric characteristics to detect regular hexagon is proposed. Hough transform and the regular hexagon characteristics are briefly introduced, and the detection of regular hexagon is decomposed into the line detection，the circle detection, the calculation of the lengths of line segments and the angles between adjacent lines. Based on the detected line segments, the line equations are constructed in the image plane. The intersection points of adjacent lines and the angles between two adjacent lines are calculated by the constructed line equations. The length of every side of regular hexagon is obtained by computing the distance between the two adjacent intersection points. The circle detection method based on Hough transform is employed to inspect whether all intersection points locate at the same circumference. The detection experiment of hexagon bolt is carried out to illustrate the performance of the presented method. The measurement errors of angles and side lengths of regular hexagon are 0.38% and 0.85% respectively. The result shows that the method is valid and can detect regular hexagon in the image precisely.