基于迭代融合的InSAR技术获取数字高程模型研究

Study on generation of DEM through iterative fusion InSAR technique

数字高程模型是重要的地理空间数据,可以提供丰富的地形信息.为了获得时效性好、分辨率高的数字高程模型,本文以南京市为实验区域,利用德国宇航局TerraSAR-X卫星同一轨道上的两幅StripMap模式SAR影像对,主从影像时间间隔只有66天,空间分辨率为3 m.采用InSAR技术,通过迭代的方法来提高获取DEM的分辨率,并结合JAXA/EORC提供的AW3D30数字表面模型与迭代后的DEM进行融合来解决阴影等问题,最终获取了南京地区的高精度数字高程模型.将实验结果分别与90 m分辨率的SRTM、30 m分辨率的ASTER GDEM、30 m分辨率的AW3D30进行相互对比分析.结果表明,相比三种常用的DEM而言,本文获取的DEM能够更精确的获取地面的细节信息,特别是对于分布稀疏的大型单体建筑物,能够很好的恢复其三维信息,但是对于建筑物分布较为密集的区域,由于传感器视线受阻,不能观测建筑物的全貌,阴影分布较多,导致此类区域的DEM结果不理想,还需进一步深入研究,提高精度及可靠性.

Digital Elevation Model(DEM)is an important Geospatial data,which can provide rich topographic information.Currently,most commonly used DEM is based on image date acquired before 2011,which has poor timeliness and fails to reflect the latest topographic features in many areas,especially in urban areas where the topographic features are rapidly updated.Therefore,it is necessary to study DEM generation methods in urban areas to provide DEM support for further studies on municipal planning and surface deformation in urban areas.In this paper,we use two SAR images with stripmap mode,single-polarization(HH),same orbit(ascending),and single look complex as experimental data from TerraSAR-X satellites.The imaging time of master and slave images was December 2,2014 and February 6,2015.The time baseline was 66 days and the space baseline was 233 m.We detected the DEM with good timeliness and high resolution of Nanjing area by the iteration and fusion technology based on two SAR images with stripmap mode from TerraSAR-X satellite and AW3D30 DEM from JAXA/EORC.Compared with SRTM,ASTER GDEM and AW3D30 respectively with the resolution of 90 m,30 m and 30 m,we find that the DEM detected by the iteration and fusion technology can show more ground details,especially for the large single buildings at the sparse area.However,the detected DEM at the area with dense buildings has the low reliability,due to the obstruct of sensor line of sight and the distribution of shadow.In summary,it is feasible to obtain high-resolution DEM by the iteration and fusion technology.It can improve the resolution of DEM by iteratively,resolve overlay and shadow by fusion with AW3D30.Thereby,the digital elevation model with high precision and high time efficiency is obtained,and the update of the topographic on the original DEM is realized.