Digital Elevation Model (DEM)
Overview
Digital Elevation Model (DEM) is a raster representation of the Earth’s surface that provides elevation data for terrain analysis and modeling in GIS. DEMs can represent either the bare ground surface (DTM) or the surface including features like buildings and vegetation (DSM).
Key Concepts
Elevation is the height above a reference datum (usually mean sea level). Cell/Pixel value stores the elevation for that ground area. Resolution is the horizontal ground distance represented by each cell. Vertical accuracy is the precision of elevation values. Void/NoData represents areas with missing elevation data.
DEM Types
| Type | Description |
|---|---|
| DTM | Bare ground (Digital Terrain Model) |
| DSM | Surface with features (Digital Surface Model) |
| DEM | Generic term for elevation models |
Common DEM Sources
| Source | Resolution | Coverage |
|---|---|---|
| SRTM | 30m/90m | Global |
| NED/3DEP | 10m/1m | United States |
| ASTER | 30m | Global |
| LiDAR | 1-3m | Regional |
Derived Products
- Slope
- Aspect
- Hillshade
- Contour lines
- Watersheds
- Viewsheds
Appendix
Created: 2025-12-13 | Modified: 2025-12-13