结合透视投影模型、非参数化的光学畸变模型以及光束平差算法,提出并实现了一种标定显微立体视觉系统光路的方法.首先,通过光刻方法制作了用于显微立体视觉系统标定的标定参考物,并利用待标定系统采集标定参考物不同方位的图像.然后,基于非参数化的光学畸变模型,采用样条曲面计算得到显微立体视觉系统的畸变校正场,并结合透视投影模型建立显微立体视觉系统的完整成像模型.最后,利用光束平差算法对所建立的成像模型进行标定计算和优化调整.搭建了显微立体视觉小尺度测量装置,验证了提出的标定方法的可行性.通过标定获得了测量装置两个光路的焦距和相对方位等参数,并借助于高精度四轴位移台对标定结果进行了精度验证.结果表明,采用本文方法标定后位移测量的精度优于1%,能够满足微胀形实验中三维变形测量的要求.该标定方法也可用于其他显微视觉检测领域.
An accurate calibration method for stereo microscope measurement systems was proposed based on a projection model,a non-parametric distortion model and the bundle adjustment algorithm.The key technologies involved were investigated.Firstly,a calibration target was designed by using the lithography method,and the images of the target were recorded from different orientations by using two cameras.Then,the distortion correction fields were calculated by using the spline surface and the non-parametric distortion model,and a complete micro-vision imaging model was established based on a perspective projective model.Finally,the calibration calculation and optimization for the imaging model were performed by using the bundle adjustment algorithm.To validate the performance of the proposed method,a stereo microscope setup was developed for small-scale deformation measurement.By using an electronically controlled displacement setup,experiments for microscopic calibration and displacement measurement were conducted.Experimental results demonstrate that the focal length and the relative orientation parameters of the internal optics of the setup is obtained,and the displacement measurement accuracy is better than 1%.It concludes that the proposed method satisfies the accuracy requirement of the 3D deformation measurement during bulging processes and is also suitable for other microscopic vision measuring fields.