Assessing the Quality of Freely Available Digital Elevation Models (DEMs) over Wasit Region, Iraq


Lobna Mahmood Badr, Dr. Maythm Al-Bakri, Assistant Professor
Department of Surveying College of Engineering University of Baghdad, Iraq.


The accuracy of Digital Elevation Models (DEMs) is often varying and is non-uniform within each dataset. DEMs is essential for Earth science and hydrological applications. It can be generated using photogrammetry, interferometry, ground and laser surveying, and other techniques. Some of the DEMs are freely available (open-source) products such as ASTER GDEM 30m,SRTM DEM 30m, Merge GHT 30m and ALOS PALSAR12.5m.In this research the quality of open source DEMs has been evaluated based on topographic maps and field surveying data. The DEMs have been created and compared using a set of tools within ArcGIS software. The comparison between the surfaces (interpolation surfaces)that were derived from the topographic map points (spot points) with the free surfaces DEM (ASTER30, SRTM30, Merge30 and ALOS PALSAR12.5)showed that the Merge DEM with RMSE of 2.303m is the best and SRTM is the second with RMSE of 2.452m, ASTER RMSE of 2.965m and ALOS PALSAR of 3.643m.