Evaluation of the Efficiency of SfM-Photogrammetry in Obtaining DEM from Google Earth Images

Abstract

In this study, we seek to evaluate the efficiency of SfM Photogrammetry in obtaining Digital Elevation Model (DEM) from the free Google Earth browser, by simulating the aerial photography of the terrain displayed by this browser, calculating the resulting block of images, and obtaining DEM, and evaluate its accuracy to know the type of works in which this model can be used. Control data for image orientation are provided using Google Earth and free online services.The results showed that the huge number of dense point cloud generated by applying SfM to Google Earth images has contributed to obtaining a DEM with a vertical accuracy better than the vertical accuracy of the free digital elevation model SRTM1. The achieved vertical accuracy of the DEM produced by SfM was 3.58 m, whereas the vertical accuracy of the free SRTM1 was 4.65 m compared to a DEM derived 1/25000 scale topographic map. This type of DEM can be used in works that do not require high vertical accuracy such as hydrological works (watersheds) dealing with SRTM models.

Keywords

• digital elevation model (dem)
• srtm
• structure from motion (sfm)
• google earth