A Comparative Study of The Slope and Elevation of The GDEMs and Local DEMs

In this comparative study, three global DEMs, namely, SRTM90, SRTM30 and ASTER have been compared to a national DEM, derived from 1:25000 maps by NCC of Iran. The goal of this study is to assess the accuracy of different DEMs, and lastly show which of them matches both NCC and reality more closely. To achieve these goals, a reference DEM has been derived from 1:2000 maps of the areas in question. Experimental results on two different areas showed that NCC DEM outperforms than the other DEMs. As is obvious, SRTM30 matches both NCC DEM and reality more closely. This relationship is true for slope products except for SRTM90, which is sensitive to the topography. This product has minimal correlation with reference DEM, derived from 1:2000 maps. Generally speaking, RMSE values of slope data are similar for all four DEMs in the two case studies, implying that slope data are more robust than the elevation data.