ASTER and SRTM are two possible world sources for DEM covering the whole country.On the other hand, topographic maps of different scales are considered as local and reliable sources of DEM data. In this paper fusion among these DEMs is applied to produce a more accurate and detailed DEM for the studying area. First, ASTER DEM was co-registered to the horizontal coordinate system of the local DEM based on road intersection as distinct features. Second, the ASTER DEM was shifted vertically to the mean elevation of the SRTM. Several strategies integration among the three DEMs had been made. Low pass filtering technique through surfer software is applied to the fused DEMs to remove the erroneous frequency components from them. Fusion and filtration processes made an enormous improvement especially in the case of integrating the data of the three DEMs. Since the fusion was applied to 30m, 90m and 200m resolution input DEMs, the fused DEM had the least grid size of resolution. The approach showed improved DEMs accuracy and completeness while maintaining the highest resolution of the input DEMs.The resulted RMSE of the fused DEM was 4.55m, which make it useful for many applications as producing topographic maps of scale 1:50,000. |
