Global DEMs’ accuracy improvement with respect to local DEM data

Today there is a great variety of DEMs: global and local. In contrast to local DEMs, the global DEMs offer extensive coverage but they are less accurate. This paper proposes the improvement of the accuracy of global DEMs locally by fitting them to more accurate local DEMs. A combination of the exhaustive search and divide-and-conquer algorithms is used to compute the planar displacement of the global DEMs which minimizes the RMSE of the elevations. The method is applied to 3 test sites all over Greece using the SRTM and the ASTER global DEMs and more accurate local DEMs, with encouraging results.