Assessment of FABDEM on the Different Types of Topographic Regions in India Using Differential GPS Data

The Forest and Buildings removed Copernicus DEM (FABDEM) represents a global DEM generated through the elimination of height biases arising due to buildings and trees in the Copernicus global 30 m (GLO-30) digital elevation model (DEM). Copernicus GLO-30 DEM is a digital surface model (DSM) generated from edited DEM called WorldDEM, which in itself is a product generated from SAR Interferometry (InSAR)-based TanDEM-X DEM. It has the potential to be used as a digital terrain model (DTM) for many applications, such as in engineering, environmental, and hydrological studies. The current experiment evaluates the accuracy of FABDEM using ground control points (GCPs) collected through a Differential GPS (DGPS) survey at the three experimental sites in India, namely, the Dehradun site in Uttarakhand, Jaipur site in Rajasthan, and Kendrapara site in Odisha. The selected three experimental sites represent varied topographic conditions in the Indian region. The FABDEM heights are converted into WGS84 heights using geoidal undulations (N) as per the Earth Gravitational Model-EGM2008, which is the vertical datum for FABDEM. Statistical measures such as MAE, RMSE, and LE90 are used to assess the accuracies of FABDEM. The RMSE computed for FABDEM in the sites at Dehradun, Jaipur, and Kendrapara are 5.96 m, 2.77 m, and 4.29 m, respectively. The study thus reveals that the FABDEM has relatively high accuracy in the experimental sites at Jaipur and Dehradun, considering their topography. However, the accuracy was found to be relatively low in the alluvial plains of the Kendrapara site.