为解决基于单张图像的传统无人机对地定位方法的精度不能满足精确打击作战需求的问题,本文提出一种新的无人机对地定位方法.该方法通过线性化共线条件方程建立摄像机姿态角和焦距迭代计算模型,根据非共线位置拍摄的多帧图像及至少3个可识别同名像点坐标迭代计算摄像机姿态角和焦距的精确值,然后利用多摄站前方交会法求取地面目标的三维坐标.该方法不依赖于数字高程模型(DEM)及像片内外方位元素的测量值,消除了传统无人机对地定位方法三个定位误差源中的两个,因此具有较高的定位精度.仿真与真实图像实验计算表明:摄站本身坐标误差的大小是决定对地定位精度的主要因素,当采用DGPS定位摄站时,可以获得很高的目标定位精度.

The accuracy of traditional single image based on geo-location method using Unmanned Aerial Vehicle (UAV)is too low to meet the needs of precise strike. To solve the problem, a new UAV geo-location method is presented in this article. The mathematical models are constructed by linearizing the colinearity equations and iteratively computing the pose angles and focal length of the camera. At least three images of the target, along with at least three identifiable common points among the images, are needed for reckoning camera pose angles and focal length. The three dimensional (3D) coordinates of ground target are calculated using forward intersection. The new method can get the target coordinates without dependence on Digital Elevation Model (DEM). Measured values of camera pose angles are not used directly for geo-location. Two of the three primary error sources in the traditional UAV target location approach are eliminated. Simulation and real image experiment results show that the accuracy of the estimated target location is very high if the UAV is navigated by Differential Global Positioning Systems (DGPS).