Comparative evaluation of verticalaccuracy of ground control pointsfrom ASTER-DEM SRTM-DEM with respectto ALOS-DEM

The concept of Digital Elevation Model (DEM) has put on by Miller in the 1950s. Digital Elevation Model is a continuous surface of the elevation from which terrain attributes (slope, aspect, curvature, topographic index, drainage area and network) are extracted. DEM represents the topographic surface with a set of three-dimensional coordinates, and it also represents the numerical representation of the ground surface, mainly for computer operations. Shuttle Radar Topography Mission is a project conducted in collaboration between NASA, the U.S. National Geographic-Intelligence Agency (NGA), the U.S. Department of Defense, DLR and Agenzia Spaziale Italiana. The Advanced Space borne Thermal Emission and Reflectance Radiometer Global Digital Elevation Model (ASTER GDEM) is a product generated from optical data collected by the ASTER instrument onboard NASA's Terra satellite. ALOS DEM, The Japan Aerospace Exploration Agency (JAXA) released "ALOS World 3D – 30m (AW3D30)" open global DEM, the global digital surface model (DSM) dataset with a horizontal resolution of approximately 30-meter mesh (1×1 arc second). The purpose of this study, the distribution of GCPs AW3D30, SRTM and ASTER city of Gaziantep to say, is to analyze the impact of vertical accuracy on Turkey. The study area Gaziantep is located between 36o 28' and 38o 01' eastern longitudes and 36o 38'and 37o 32'northern latitudes. The vertical accuracy of each points selected from ASTER, SRTM regard to ALOS DEMs were estimated by using methods explained in methodology over GCP's vertical component (Z component) of ASTER, SRTM and ALOS, seriatimly. The results observed from the RMSE, R-RMSE, MAE, NRMSE and RMSE% of selected GCPs were plotted. The vertical accuracy are derived by finding the difference between the points Z component (from ALOS DEM) and the points Z component computed from different SRTM DEM and ASTER DEM for finding the vertical accuracy. The results indicate that the vertical accuracies can be improved for all the plotted points. We also compared the vertical accuracy of ALOS AW3D30 with respect to ASTER and SRTM datasets on different land cover types such as plain area, open forests, city area, hilly part areas. The land cover types and terrain slopes jointly contribute to the accuracy variations of the samples, and the latter is likely to have a greater impact than the former. The analysis indicates that ALOS AW3D30 provides the best accuracy of analysis vertical accuracy of ground control points, followed by SRTM, and then by ASTER GDEM2 DEMs.