DIGITAL ELEVATION MODELS FROM ORBITAL SENSORS FOR TERRAIN ANALYSIS

Abstract

Digital Elevation Models (DEMs) generated from orbital sensors play a fundamental role in terrain analysis, allowing precise information to be collected on the topography of the earth's surface. The main satellites that contribute to the creation of these models include SRTM (Shuttle Radar Topography Mission), ALOS (Advanced Land Observing Satellite), the Copernicus mission satellites and NASADEM (NASA Digital Elevation Model). Therefore, the objective was to study digital elevation models from orbital sensors for terrain analysis with images obtained from the SRTM, Alos Palsar, Copernicus and Nasadem projects in order to obtain topographic information for the state of Mato Grosso do Sul. The study area was the state of Mato Grosso do Sul, which is in the Center-West region of Brazil. The radar images were obtained from the “OpenTopography DEM Downloader” plugin in the QGIS software with data from the projects: SRTM; Alos World; Copernicus Global DSM; Nasadem Global DEM. The images were downloaded from the four mesoregions of the state of Mato Grosso do Sul, which are: Pantanal, Center North, East and Southwest. Thus, four images were downloaded from each project. After processing the images, the altimetry, slope and terrain roughness index maps were obtained. The data was subjected to descriptive statistics. With the maps reclassified, the Kappa index was calculated to compare the data from each radar. The altimetry data from the SRTM, Alos, Copernicus and Nasadem projects show close kappa and global accuracy values, indicating that they can be used without distinguishing between the maps. The digital elevation models from the SRTM and Nasadem projects are very similar and show greater overall accuracy when calculating slope and terrain roughness index.