采用最大灰度梯度法实现经纬仪自动调焦控制  

Auto-focusing adjustment of theodolites by largest the gradient method

作　　者：梁敏华[1,2] 吴志勇[1] 陈涛[1] 

机构地区：[1]中国科学院长春光学精密机械与物理研究所,吉林长春130033 [2]中国科学院研究生院,北京100039

出　　处：《光学精密工程》2009年第12期3016-3021,共6页Optics and Precision Engineering

基　　金：国家863高技术研究发展计划资助项目(No.2006AA703104)

摘　　要：提出了一种基于最大灰度梯度的经纬仪自动对焦方法,以CMOS相机为图像传感器,用计算机进行数据处理并控制驱动电路调整相机镜头的位置来实现自动调焦。首先,选择包含主体成像目标的最小区域作为对焦选择区域,不仅有效地节省了系统处理图像的时间,而且极大地减小了复杂背景对精确调焦的干扰,提高了调焦准确率;其次,求出边缘上任意可能梯度方向的梯度,比较后得到每个边缘点的最大梯度;最后,采用最大灰度梯度作为系统的自动聚焦判距。实验结果表明,系统的调焦分辨率为0.01～0.02mm,能够满足经纬仪第一像面焦深的调焦要求。该调焦算法具有单峰性强、无偏性好、灵敏度高、稳定性好以及可实时性操作等特点。by the window selection, which not only reduces the load for data processing, but also reduces the in fluence of complex background on the accurate focusing and enhances the precision of auto-focusing, Then the edge gradients in all possible directions are calculated, and all of the possible edge gradients are campared to choose the largest gradient as the criterion of auto-focusing system. The experimental result demonstrates that the system can be characterized by its good unbiased characteristics, strong single peak features, high sensitivity and good stability, and the measuring precision of the system meets the requirements of the first focus-depth of the theodolite, for it has the focusing resolutions of 0.01-0.02 m.

关 键 词：光电经纬仪 自动聚焦 评价函数 灰度梯度 对焦窗口 

分 类 号：V556.5[航空宇航科学与技术—人机与环境工程]