Enhancing DEMs for geomorphometric research through digital filtering.

Currently, Digital Elevation Models (DEMs) are the main source for representing Earth’s surface and have been an integral part of any geospatial analysis, in particular, geomorphometric research. Among existing techniques, photogrammetry is considered as a common method for obtaining high-resolution elevation data, especially over large or/and inaccessible areas. However, this DEMs are disposed to a severe amount of uncertainty. The aim of this research is to provide an optimal filtering strategy that can remove possible errors and improve the quality of raw photogrammetric DEMs for geomorphometric research over regions with relatively low relief. Results reveal that a combination of three digital filters, namely Gaussian filter, Median filter, and Slope Based filter, is able to reduce different sources of errors and improve the elevation accuracy of DEM by more than 5%, resulting in improved quality of the derived geomorphometric parameters.