基于图像匹配的长焦透镜焦距测量研究

Research on measuring telephoto lens focal length by using image matching

提出一种新的测量长焦透镜焦距的方法。采用测角精度较高的光电经纬仪,由CCD相机拍摄经纬仪中十字亮线偏移的位置图像,并记录经纬仪显示的对应角度。应用改进的互相关匹配算法及三次曲面拟合算法,对CCD拍摄的两幅图像进行快速亚像素匹配,获得关于十字亮线中心的一对亚像素匹配点坐标。最后根据经纬仪角偏移量和亚像素点偏移量求出长焦透镜的焦距,实验获得了较高的测量精度。

A new method of measuring telephoto lens focal length is presented in this paper.A high precise theodolite is adopted in the measurement,and the offset images of bright cross is taken by a CCD camera,also the angle values of the corresponding position of the theodolite are recoded simultaneously.The improved correlative matching algorithm and cubic surface fitting algorithm is adopted for the match of the two images,and a pair of coordinates of matching point in sub-pixel level are extracted.Finally,the focal length of telephoto lens can be calculated accurately according to the angle offset and the coordinate offset.The experiments show that the suggested method can give a high measurement precision.