高分辨率遥感影像DSM的改进半全局匹配生成方法

Digital Surface Model Generation for High Resolution Satellite Stereo Image Based on Modified Semi-global Matching

提出一种基于改进半全局匹配算法的高分辨率遥感影像数字表面模型(digital surface model,DSM)生成方法。首先利用影像间连接点几何约束关系对有理函数模型进行系统误差补偿,在补偿模型的基础上对影像进行分块,利用投影轨迹法逐块得到核线影像对;在密集匹配阶段,对影像建立金字塔后逐层进行半全局匹配,匹配过程中引入顾及影像纹理信息的视差图膨胀腐蚀算法约束每一层视差搜索范围,增加了视差图边缘处的有效像素数,同时减少了算法所需的内存开销和计算时间;在视差图后处理阶段,利用加权中值滤波算法保护了视差图的边缘信息;最后基于前方交会获取DSM。选取WorldView 3和资源三号立体影像进行试验,结果表明,本文方法获取的DSM精度在高程方向上接近于1.5倍GSD,并且较好地保持了地物的边缘特性,在计算效率和内存开销方面也具有较好的平衡。

A method is proposed for generating digital surface model(DSM)of high resolution satellite imagery(HRSI)based on modified semi-global matching(SGM)algorithm.Firstly,the system error of the rational function model is compensated by using the geometric constraint relation between the image connection points.Based on the compensation model,the image is divided into blocks.The projection trajectory method is used to obtain the image pairs of the images.In the dense matching stage,the disparity map is computed using semi-global matching by layer after building the pyramids images,and an expansion corrosion algorithm for disparity graphs,which takes into account the image texture information,is introduced to constrain the range of parallax search,increase the number of effective pixels at the edge of the parallax map and reduce the memory overhead and computation time required for the algorithm.In the post processing stage of disparity image,the edge information of disparity image is protected by weighted median filtering algorithm.Finally,the DSM is acquired based on the forward intersection.The stereo images of World View 3 and ZY-3 to experiment are selected.The experimental results show that the DSM accuracy obtained by this method is nearly 1.5 times higher than that of GSD in elevation direction,and the edge characteristics of the object are maintained well.The algorithm is computationally efficient and has relatively low memory overhead.