A High-accuracy Camera Calibration Method Based on Special Circular Target

Targets with circular markers are commonly used in camera calibration and vision measurement. This paper proposes a special circular target with complete and incomplete concentric circles and accordingly introduces a high-accuracy camera calibration method. This method first calculates the initial camera parameters by utilizing the improved ellipse fitting method to determine the centers of the complete concentric circles. But the fitted centers do not coincide with the real projected centers due to the perspective transformation and lens distortion. The coordinates of the real projected centers can be obtained by detecting the corners of the incomplete concentric circles and using the properties of projective geometry. Then, based on the determination of the real projected centers, the iterative compensation algorithm is proposed to eliminate the influence of the eccentricity errors and refine the camera parameters. Corresponding experiments were conducted to show the high accuracy and robustness of the proposed camera calibration method.