单目图像中姿态角估计的坦克目标测距方法  

The Attitude Angle Estimation-based Distance Measurement of Tank Target in Monocular Image

作　　者：徐超[1] 高敏[1] 曹欢 

机构地区：[1]军械工程学院导弹工程系,河北石家庄050003 [2]北京航天嘉诚精密科技发展有限公司,北京102600

出　　处：《光子学报》2015年第5期134-141,共8页Acta Photonica Sinica

基　　金：军内科技创新项目(No.2013562);军械工程学院科研基金项目(No.YJJM11018)资助

摘　　要：为了克服经典成像测距对相机姿态和视差信息依赖的问题,以观瞄发控装置的电荷耦合器件获取的单目图像为研究对象,提出了基于姿态角估计的坦克目标测距方法.该方法首先利用多级尺度不变特征变换匹配算法实现目标姿态角的快速估计,获取与当前目标姿态偏差最小的模板;然后利用该模板和目标图像模拟立体视觉,建立不依赖于相机姿态和视差的单目测距模型.该模型在远距离测距和小角度偏差的前提下,将模板中的匹配特征点投影到等效平面世界坐标系中,建立被测坦克图像点及其空间点的映射关系,将测距问题转化为对相机外参量的标定,从而求解出相机中心到坦克中心的距离.采用200m到2 500m范围内的坦克验证测距方法的性能,对测量误差随距离的变化规律进行分析,并将其与不同射程时导弹末制导交班的最大容许误差进行对比.结果表明,该方法适用于观瞄发控装置获取的任意姿态图像,实现了野战条件下单兵反坦克武器系统的远距离、快速测距;测量结果中相对误差小于4.9%,绝对误差小于87.7m,满足导弹各个射程的最大容许误差的要求.To overcome the traditional image ranging algorithm dependent on camera attitude and parallax, an attitude angle estimation-based ranging method of tank target, in monocular image cathched by observe control and launch system charge coupled device, is proposed. Firstly, multistage scale invariant feature transform matching method is applied to obtain the template with minor error comparing with current target by fast attitude angle estimation. Secondly, the template and current target are used to form a novel monocular range model, without camera attitude and parallax between two images. In such a model, the features points matching the tank target image of the template are projected to the approximated 2D world coordinate with the assumption of far distance and tiny error of the attitude. Thus we set up the mapping relationship between the image points and target points, and then external parameters of camera are achieved by monocular camera calibration to calculate the distance of the camera center from target center. Series of targets range from 200 m to 2 500 m are adopted to verify the effectiveness of the proposed algorithm. Sequentially, the alteration of error along with distance increasing is analyzed, and the comparison between measurement error and the maximal tolerance ofmiddle-to-terminal guidance under various ranges is executed. The results indicates that the proposed algorithm do not need to capture the accurate position and angle of camera, resulting in fast and far distance measurement of individual anti-tank missile system in field. Meanwhile, the maximal relative error is 4. 9% and the maximal absolute error is 87. 7 m, which satisfy the demand of the biggest tolerance errors in the whole range of missile.

关 键 词：几何光学 被动测距 姿态角估计 单目图像 反坦克导弹观瞄发控装置 小孔成像 相机标定 尺度不变特征变换 

分 类 号：TP391.4[自动化与计算机技术—计算机应用技术]