双目立体视觉系统摄像机标定

Stereovision system calibration based on dual-camera

对摄像机参数标定是三维定位的关键.制作了平面式标定板,将标定板中圆的当量中心作为标定用参考点,这样可以有效避免测量误差.采用线性和非线性结合的方法标定摄像机参数,首先利用直接线性转换模型(DLT)得到投影矩阵,通过约束条件分解参数矩阵,分别求出摄像机内部参数;然后将得到的标定参数作为初值,代入非线性方程进行优化,得到精确的标定参数.非线性优化采用Levenberg-Marquardt迭代法.试验表明,标定参数与出厂参数有一定差异,但和实际情况完全吻合.

Camera calibration is the key process in three-dimensional location of stero-vision. A planar calibration rig was made as sample, and the equivalent center of circles in the rig was taken as reference point to avoid unnecessary measuring error. To get the precise camera parameters, the linear and nonlinear methods were combined. First, Direct Linear Transform（DLT） model was used to get the projection matrix. Then the matrix was decomposed based on the restraint condition, and the intrinsic parameters of camera was estimated. These estimates were fed to the non-linear optimizer as initial guess for the calibration parameters; the Levenberg-Marquardt method was used as non-linear optimizer. The experiment indicates that the calibrated parameters have certain differences from instructions, but completely agree with the actual condition.