External Validation of the ASTER GDEM2, GMTED2010 and CGIAR-CSI- SRTM v4.1 Free Access Digital Elevation Models (DEMs) in Tunisia and Algeria

Abstract

Digital Elevation Models (DEMs) including Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER GDEM), Shuttle Radar Topography Mission (SRTM), and Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010) are freely available for nearly the entire earth's surface. DEMs that are usually subject to errors need to be evaluated using reference elevation data of higher accuracy. This work was performed to assess the vertical accuracy of the ASTER GDEM version 2, (ASTER GDEM2), the Consultative Group on International Agriculture Research-Consortium for Spatial Information (CGIAR-CSI) SRTM version 4.1 (SRTM v4.1) and the systematic subsample GMTED2010, at their original spatial resolution, using Global Navigation Satellite Systems (GNSS) validation points. Two test sites, the Anaguid Saharan platform in southern Tunisia and the Tebessa basin in north eastern Algeria, were chosen for accuracy assessment of the above mentioned DEMs, based on geostatistical and statistical measurements. Within the geostatistical approach, empirical variograms of each DEM were compared with those of the GPS validation points. Statistical measures were computed from the elevation differences between the DEM pixel value and the corresponding GPS point. For each DEM, a Root Mean Square Error (RMSE) was determined for model validation. In addition, statistical tools such as frequency histograms and Q-Q plots were used to OPEN ACCESS Remote Sens. 2014, 6 4601 evaluate error distributions in each DEM. The results indicate that the vertical accuracy of SRTM model is much higher than ASTER GDEM2 and GMTED2010 for both sites. In Anaguid test site, the vertical accuracy of SRTM is estimated 3.6 m (in terms of RMSE) 5.3 m and 4.5 m for the ASTERGDEM2 and GMTED2010 DEMs, respectively. In Tebessa test site, the overall vertical accuracy shows a RMSE of 9.8 m, 8.3 m and 9.6 m for ASTER GDEM 2, SRTM and GMTED2010 DEM, respectively. This work is the first study to report the lower accuracy of ASTER GDEM2 compared to the GMTED2010 data.

Elevation-Based Sea-Level Rise Vulnerability Assessment of Mindanao, Philippines: Are Freely-Available 30-M Dems Good Enough?

“…For the ASTER GDEM2, the computed RMSEz of 9.80 m is comparable to that of Athmania and Achour (2014) when they conducted external validation of the DEM in northeastern Algeria and obtained a similar RMSE value; and to that of Gesch et al (2012) where they computed an RMSEz of 8.68 based on the comparison of the DEM with more than 18,000 independent reference ground control points located in the conterminous US. Table 3 summarizes the results of the vertical uncertainty assessment of the three DEMs using all the GCPs.…”

Estimation of Polder Retention Capacity Based on ASTER, SRTM and LIDAR DEMs: The Case of Majdany Polder (West Poland)

“…This indicates an inadequate usefulness of generally available, free-of-charge DEMs (ASTER and SRTM) for capacity and hydrodynamic modeling of a polder. However, in other studies [54,57,70] correlations R 2 for elevation are above 0.9 for large areas. Depending on region [55], there is no obvious relationship between the DEM-GCP (Ground Control Points) differences and actual elevation for either ASTER or the reference DEMs.…”

“…The average errors of DEMs from ASTER stereoscopic images for flood areas reach just below 20 m [51]. Therefore, while comparing both free data sources, one can note that DEMs based on the SRTM mission (although with a worse resolution than that of ASTER) is more accurate and closer to the reference models [52][53][54][55][56][57]. DEMs may also be constructed as a combination of these two models [58] and, for example, OpenStreetMap [4].…”

Investigating the Influence of Different DEMs on GIS-Based Cost Distance Modeling for Site Catchment Analysis of Prehistoric Sites in Andalusia

“…Mukherjee et al [14] and Li et al [63] assessed that the vertical accuracy of the ASTER GDEM V2 is higher than that of the SRTM-3 DEM in their study area. However, in spite of the higher horizontal resolution of the ASTER GDEM V2, other studies from Athmania and Achour [55], Suwandana et al [64], Rexer and Hirt [65], Pulighe [66] attest that the SRTM v4.1 (SRTM-3) data have a higher or similar [67] vertical accuracy as the ASTER GDEM V2 [55,[64][65][66]. The work of Tachikawa et al [53] shows for the U.S. that the absolute vertical accuracy of the one-arc second SRTM DEM is higher than that of the ASTER GDEM V2 (see also Table 1).…”