ASSESSING THE VERTICAL ACCURACY OF FREE GLOBAL DIGITAL ELEVATION MODELS OVER EGYPTIAN TERRITORY

Document Type : Original Article

Authors

1 Faculty of Engineering, October 6 University, Construction, and Building Department

2 Lecturer, Civil Eng. Department, Giza High Institute of Engineering &Technology (GEI), Giza, Egypt.

Abstract

The Advanced Land Observing Satellite (ALOS World-30m), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER-30 m), and Shuttle Radar Topography Mission (SRTM-30m) are freely available global digital elevation models (GDEMs) with a 30-meter horizontal resolution. These DEMs have applications in areas like topography, geomorphology, and hydrology. The study evaluated the vertical accuracy of these three DEM products over 4 selected regions in Egypt using ground control points (GCPs) from differential global positioning system (DGPS) as a reference. The results showed that the ALOS DEM had the lowest root mean square error (RMSE) compared to the SRTM-30m and ASTER GDEM2 products across the 4 study areas. Specifically, the ALOS DEM RMSE ranged from 0.95m to 2.59m, while the SRTM-30m RMSE was 2.21m to 4.47m, and the ASTER GDEM2 RMSE was 6.74m to 17.42m. The ALOS DEM tended to overestimate the true ground elevations, also its vertical accuracy was superior to the other two DEM products tested. Based on the results, ALOS can be used for producing 1:50,000 topographic maps, its elevation RMSE is less than half of the contour interval used in these maps. analysis concluded that the ALOS DEM is more accurate than SRTM-30m and ASTER GDEM2 for the regions studied and that users of these global DEM datasets in Egypt should be aware of their relative vertical accuracy when applying them to various applications.

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Journal of Al-Azhar University Engineering Sector
Volume 20, Issue 74
January 2025
Pages 17-31

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