中文摘要：

提出了一种简便易行的双目立体测量系统标定的三步法。利用平面标定板的射影变换性质，闭式求解摄像机的线性内外参数；以此为初始值，以重投影误差为目标函数，采用非线性优化算法优化内外参数；考虑标定靶标存在的几何误差，将靶标的三维坐标也作为优化参数进行优化。不同于传统的两步标定算法，三步标定算法不严格依赖于标定靶标的精度，而是通过优化算法精确地得到实际的三维靶标点坐标，从而消减了靶标误差对标定精度的影响。标定实验和系统标定后的三维重建结果验证了该方法的合理性和对于提高标定精度的有效性。

英文摘要：

A practical 3--step binocular camera calibration method was proposed herein. Firstly, assuming pin--hole model,the internal and external parameters＇ initial values were estimated by using projective transformation principles. Secondly, the parameters were optimized by LM nonlinear optimization algorithm taking last step＇s results as initial values and targeting at minimizing re-- projection errors. Thirdly and lastly,another LM optimization was conducted adding plate＇s feature 3D coordinates as optimization parameters, after.wards real metrics were obtained by scaling. Compared to traditional 2 -- step calibration, instead of strictly assuming calibration object＇s 3D precision, this method takes great advantages of nonlinear optimization algorithm to get real features＇ 3D coordinates, thus eliminating the infection of errors of 3D features on calibration. The validity and efficiency of our method can be demonstrated by the results of post--calibration 3D reconstruction experiments.