A pointer location algorithm for computer visionbased automatic reading recognition of pointer gauges

In order to implement a computer vision based reading recognition system for pointer gauges, we propose an algorithm to locate the pointer by searching for the minimal bounding rectangle (MBR) of the pointer region. Having determined the center of dial region and the centroids of scale marks, we build up a reference system for reading recognition with the dial region center and the scale mark centroids. To identify the indicating value of a gauge image, we first detect the pointer region based on frame difference, and determine the MBR of the pointer using the longest edge of its convex hull. We then take the centroid of the MBR enclosing the pointer region as the centroid of the pointer. We next take the connection between the pointer centroid to the dial center as the pointer, and calculate the indicating value corresponding to the pointer based on the angle method. Experimental results reveal the effectiveness of the pointer location algorithm in computer vision based reading recognition for pointer gauges.