Digital Elevation Model
Definition
A Digital Elevation Model (DEM) is a raster-based representation of the Earth's surface, where each cell contains an elevation value. DEMs are foundational in GIS for terrain analysis, 3D modeling, hydrological studies, and landscape visualization. They may be generated through satellite imagery, LiDAR, photogrammetry, or radar data.
Application
DEMs are used in flood modeling, slope analysis, infrastructure design, and visibility studies. In hydrology, they help derive flow direction, watersheds, and stream networks. Urban planners assess site suitability, while military analysts use them for line-of-sight calculations. GIS platforms like ArcGIS and QGIS offer terrain tools to extract contour lines, hillshades, and viewsheds from DEMs.
FAQ
What are common sources of DEMs?
LiDAR, SRTM, ASTER, drone surveys, and aerial photogrammetry.
How are DEMs used in hydrology?
They support watershed delineation, runoff modeling, and floodplain mapping.
What is the resolution of a DEM?
It varies from sub-meter (LiDAR) to 30m (SRTM) or more, depending on the data source.
Why are DEMs essential in GIS?
They enable elevation-based analysis critical for planning, safety, and environmental modeling.
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