Novel camera calibration method based on invariance of collinear points and pole–polar constraint

To address the eccentric error of circular marks in camera calibration, a circle location method based on the invariance of collinear points and pole–polar constraint is proposed in this paper. Firstly, the centers of the ellipses are extracted, and the real concentric circle center projection equation is established by exploiting the cross ratio invariance of the collinear points. Subsequently, since the infinite lines passing through the centers of the marks are parallel, the other center projection coordinates are expressed as the solution problem of linear equations. The problem of projection deviation caused by using the center of the ellipse as the real circle center projection is addressed, and the results are utilized as the true image points to achieve the high precision camera calibration. As demonstrated by the simulations and practical experiments, the proposed method performs a better location and calibration performance by achieving the actual center projection of circular marks. The relevant results confirm the precision and robustness of the proposed approach.