DEM generation from Worldview-2 stereo imagery and vertical accuracy assessment for its application in active tectonics

摘要

The DEM-generation technology from high-resolution satellite imagery enables us to generate a wide range of high resolution topographic data rapidly, improving the efficiency of data acquisition greatly. This method is more efficient than airborne Light Detection And Ranging (LiDAR) in terrain reconstruction, since satellite imagery covers a larger area without difficulties in field deployment. Previous researches evaluated the accuracy of DEMs generated from stereo imagery of different satellite sensors, however there is not enough quantitative analysis concerning the capability of satellite-based DEM in active tectonic studies. Therefore, in this paper, we presented a study to investigate the accuracy to measure heights of fault scarps using the DEM obtained from Worldview-2 stereo imagery and chose the Kumysh fault in the southern margin of Kumysh Basin (Eastern Tian Shan, China) as our test site. Point cloud data were obtained from stereo satellite imagery, both with and without GCPs respectively. Prior to the generation of the DEM, we compared the overall elevation differences of the point clouds and the fault scarp swaths. The overall elevation difference ranges from -1.2 to 0.4 m, with the mean value of -0.57 m, while the elevation difference of fault scarp swaths range from -1.1 to 0 m, with the mean value of -0.4 m. Afterwards, we generated a 0.5 m resolution DEM of 5-km swath along the Kumysh fault, measured the heights of fault scarps on different levels of alluvial fans, and compared the topographic profiles obtained from DEM and post processed differential GPS (ppGPS) survey. Our results show that: (1) the elevation difference between the topographic profiles ranges from -2.82-4.47 m, the shape of the fault scarp can be accurately reconstructed by satellite-based DEM with the deviation of 029 m after elevation correction; (2) the accuracy of the height measurement of fault scarps can reach 0.25 m. These findings indicate that the DEM generated from Worldview-2 stereo imagery is capable of measuring relative deformed topographic features, which could be of great interest to professionals exploring the use and accuracy of satellite stereo imagery for active tectonic applications. (C) 2019 The Authors. Published by Elsevier B.V.