The precision circle target sub-pixel centroid location is one of the key factors of large space 3D coordinates measurement. In this paper, the circle retro-reflective targets and optical targets used in large space 3D coordinates measurement are analyzed, and the characteristics and applied fields of target sub-pixel centroid location algorithms such as gray weighted and squared gray weighted centroid location algorithms which combine with bi-linear interpolation or improved cubic convolution interpolation method, are discussed. The influencing factors and improving methods for circle target location are also analyzed. These factors include the resolution of the CCD camera, image grab noise, the size of targets, the choice of exposure time and threshold value, the noncoincidence of centroid and center of the ellipse imaging targets, the distortion influence of deformational targets and so on. Based on these, proper compensating measures are brought out for the problems such as target choice and location, influencing factors and eliminating measures.
Discussion(0)
No comments yet. Be the first to comment.