Evaluating the Performance of SRTM, NASADEM, and Copernicus DEM: A Case Study of the Perlis State Region

Digital Elevation Models (DEMs) are fundamental tools for various applications including flood risk mapping, geoid modelling, and terrain analysis. The increasing availability of global DEMs (GDEMs) such as the Shuttle Radar Topography Mission (SRTM), NASADEM, and Copernicus DEM (CopDEM) has enhanced the accessibility of elevation data worldwide. However, their accuracy varies depending on topographic characteristics and data acquisition methods. This study aims to evaluate the performance of SRTM, NASADEM, and CopDEM over the Perlis State region in Malaysia. Ground truth data were obtained from 38 GNSS benchmarks and 1,177 ICESat ATLAS08 altimetry points. Prior to analysis, ellipsoidal heights were converted to orthometric heights using the EGM96 geoid model. DEM elevation values were interpolated at each validation point, and accuracy was assessed using Mean Error (ME), Standard Deviation (STD), and Root Mean Square Error (RMSE). The results reveal that NASADEM exhibits the highest accuracy, with RMSE values of 1.855 m (GNSS) and 5.814 m (ICESat), followed by CopDEM and SRTM DEM. All three GDEMs show strong positive correlations with ground truth data, with correlation coefficients exceeding 0.98. These findings indicate that NASADEM provides more reliable elevation data in the Perlis region, especially in relatively flat areas. The study contributes to informed decision-making in selecting appropriate DEMs for environmental and geospatial applications in similar terrains.