基于空间共线点的单光心反射折射摄像机标定

Central Catadioptric Camera Calibration Based on Collinear Space Points

一条空间直线的单光心反射折射图像是一个二次曲线段,大多数利用直线进行单光心反射折射摄像机标定的方法都需要对直线的像进行二次曲线拟合,曲线拟合的精度严重影响着标定的精度.然而,一条空间直线的像仅占整个二次曲线的一小段,这使得曲线拟合的效果非常差.本文利用空间三个共线点的反射折射投影给出了摄像机内参数的一个非线性约束.当反射镜面为抛物面时,在主点已知的情况下,该约束变为线性约束.如其他参数已知,该约束变为关于有效焦距的多项式约束.由此,本文提出了三种不同条件下的标定算法,算法中无需对直线的像进行二次曲线拟合,无需场景的任何信息,标定精度较高.实验验证了算法的有效性.

For central catadioptric cameras, the projection of a space line is a conic segment, and most of the calibration methods using lines need conic fitting of line images, which highly affects the calibration accuracy. However, generally only a small segment of the conic is visible, which makes the conic fitting error-prone. In this paper, we derive a nonlinear constraint on all camera intrinsic parameters from the projections of any three collinear space points. With the principal point known, the constraint becomes linear for para-catadioptric cameras. With all other parameters known, the constraint becomes a polynomial constraint on the effective focal length. Based on this constraint, we propose three calibration algorithms under different conditions. The proposed algorithms need no conic fitting of line images, need no scene information, and the calibration accuracy is high. Experiments demonstrate the efficiency of the proposed algorithms.