An improved method for location of concentric circles in vision measurement

Target with concentric circles has been widely used in camera calibration and vision measurement systems. An improved method to accurately locate the real projection of the concentric circles center has been proposed in this paper. Compared with similar methods, this method is computational efficiency and has no requirement of the concentric circles' radii. Several simulations have been carried out to explore the influence of image noises, rotation angle, inner radius, outer radius and circle number to the center location accuracy, and several quantitative or semi-quantitative conclusions have been obtained, which can guide the optimum design of concentric circle target. Verification experiment was designed and result shows it is about 0.0891 pixel in accuracy and has promoted the computational efficiency scores of times. Moreover, a planar calibration target was designed and used to calibrate a binocular stereovision system, and test result shows the RMS error of the system has been improved to 0.0284 mm.