为了用普通低成本的广角镜头摄像机实现较大视场的精确定量的图像测量，必须对畸变图像进行校正。提出了一种简单而精确的径向畸变标定方法，该方法使用栅格阵列标定模板。首先根据畸变图像中特征点之间的相互位置关系构造出理想图像中的特征点位置；然后以不同的畸变中心假设，计算畸变和理想特征点的矢径坐标，并通过解线性方程组或多项式拟合求出它们之间的函数关系；最后取矢径均方误差最小的参数组作为标定结果。该法可同时获得畸变变换和矫正变换的参数。文中还推导了畸变变换多项式系数与校正图像分辨率之间的反幂比例关系，讨论了畸变函数的阶对校正结果的影响，实验结果表明，取4阶或5阶多项式拟合的结果较好。

To implement accurate metric measurement within a large field of view with common off the shelf cameras, the image distortion caused by wide angle lenses should be corrected. A simple and precise method for calibrating the radial distortion is proposed. Any planar pattern in which the feature points form a grid can be used to obtain the calibration image. The proposed method first constructs an ideal image based on the positions of feature points extracted from the distorted image. Then the radial coordinates of the distorted and ideal feature points are calculated under the hypothesis of given center of distortion, and the relation function between the ideal and distorted radial coordinates is obtained by solving linear equations or by polynomial fitting. The set of parameters with the minimum mean square error is regarded as the calibration result. One merit of the proposed method is that both the undistorted to distorted and distorted to undistorted expression can be obtained at the same time by the same way. Moreover, the inverse power proportion relation between calibration result and resolution of rectified image is derived, and the influence of the order of distortion function on rectified image is discussed. Experiment results show that 4th or 5th order function would result better outcome.