Under central catadioptric camera, the projection of a line in space is a conic curve. Due to the partial occlusion, only a small arc of the conic curve is visible on the image plane, thus it is very difficult to correctly estimate the line image from its visible part, which affects the calibration accuracy of the camera. What's more, the existing method in the literatures cannot still solve this problem effectively. In addition, according to the image formation of central catadioptric camera, we find that if the antipodal points of image points on the visible arc are known, the fitting accuracy can be improved greatly. In this paper, we propose a new catadioptric line fitting method, which is suitable to all kinds of central catadioptric cameras. Firstly, a new relationship between a pair of antipodal image points and the camera principal point are derived. Next, based on the relationship, a new objection function is established to estimate the line images. Finally, these estimated line images are used to calibrate camera intrinsic parameters to evaluate the performance of the fitting method. Experimental results on both simulated and real image data have demonstrated the effectiveness of the fitting method. That is, our method not only has good robustness but also can improve the fitting accuracy of central catadioptric line images and the calibration accuracy of the camera intrinsic parameters.%直线在中心反射折射摄像机下的像是一条二次曲线.由于存在遮挡,准确地拟合直线像是非常困难的,从而影响了摄像机的标定精度.目前,这一问题仍然没有得到有效的解决.此外,根据中心反射折射摄像机成像模型发现,如果可见弧上图像点的对极点已知,可以大大提高直线像的拟合精度.为此,提出了一种新的拟合直线像的方法,该方法适用于包括抛物反射折射摄像机在内的所有中心反射折射摄像机.首先,推导出一种新的关于对极图像点与摄像机主点之间的关系；然后,通过这种关系建立目标函数,用来优化得到直线像的方程；最后,利用拟合的直线像估计摄像机的内参数,以此评价拟合算法的性能.大量模拟实验和真实实验均验证了拟合算法的有效性,即提出的拟合算法不仅鲁棒,且提高了直线像的拟合精度,进而提高了摄像机的标定精度.
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