为了方便而精确地进行摄像机标定,提出了一种基于射影不变量的求解摄像机内参数的方法,该方法利用交比在射影变换中不变的性质,通过同一平面中相交直线的无穷远点与虚圆点的交比,先求出同一模板的不同方位的3幅图像中的虚圆点的像;然后利用绝对二次曲线的像在摄像机做刚体运动时保持不变的性质,进而求出绝对二次曲线的像;最后对结果进行Cholesky分解,就可以得到摄像机的内参数。实验表明,该方法行之有效,可以达到较高的精度。

In this paper,a method of camera self-calibration based on the projective invariant is proposed.By the invariability of Cross Ratio in projective transform,we can compute the image of circular points via the cross ratio of circular points and vanish points of intersecting lines;With the image of circular points in three images of the planar pattern from different orientation,we can get IAC(Image of Absolute Conic),because of the invariability of IAC in rigid motion;Using Cholesky factorization on IAC,we get internal parameters of the camera.The result of experiments shows that this method is effective and has high precision.