Laser stripe center extraction is a key step for the profile measurement of line structured\nlight sensors (LSLS). To accurately obtain the center coordinates at sub-pixel level, an improved\ngray-gravity method (IGGM) was proposed. Firstly, the center points of the stripe were computed\nusing the gray-gravity method (GGM) for all columns of the image. By fitting these points using the\nmoving least squares algorithm, the tangential vector, the normal vector and the radius of curvature\ncan be robustly obtained. One rectangular region could be defined around each of the center points.\nIts two sides that are parallel to the tangential vector could alter their lengths according to the\nradius of the curvature. After that, the coordinate for each center point was recalculated within the\nrectangular region and in the direction of the normal vector. The center uncertainty was also analyzed\nbased on the Monte Carlo method. The obtained experimental results indicate that the IGGM is\nsuitable for both the smooth stripes and the ones with sharp corners. The high accuracy center points\ncan be obtained at a relatively low computation cost. The measured results of the stairs and the screw\nsurface further demonstrate the effectiveness of the method.
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