Digital Elevation Model
Definition
A Digital Elevation Model (DEM) is a 3D representation of a terrain's surface created from elevation data. It is a digital model or three-dimensional representation of a geographic area's terrain's surface, generally excluding vegetation and buildings. The data is collected in the form of geographical coordinates and altitude information.
What is Digital Elevation Model?
A Digital Elevation Model can be simply understood as a digital model or a three-dimensional (3D) representation of a terrain's surface. The data is often gathered through remote sensing techniques from air, space-borne platforms, or on-the-ground measurements and is then used in various fields including geography, hydrology, ecology, spatial analysis, city planning, and surveying to mention a few.
The DEM consists of a grid of cells or set of points in which each cell or point has an associated altitude value. This elevation data can be derived from various sources such as satellite sensors, aerial photos, Light Detection and Ranging (LiDAR) technology, and Interferometric Synthetic Aperture Radar.
There are typically three types of Digital Elevation Models: Digital Surface Models (DSM), Digital Terrain Models (DTM), and Digital Height Models (DHM). DSM represents the earth’s surface and includes all objects on it, DTM represents the bare ground surface without any objects, and DHM is a model of elevations of the terrain’s surface.
FAQs
Where are Digital Elevation Models used?
A Digital Elevation Model is widely used in a variety of fields such as cartography, topography, civil engineering, and environmental studies. These models are fundamental for flood risk mapping, land use planning, geological studies, and structural engineering, among others.
How is a Digital Elevation Model created?
Digital Elevation Models are created using different remote sensing techniques. These techniques may include satellite imagery, aerial photography, LiDAR, or radar interferometry. Each method has its pros and cons, but all provide valuable data for creating DEMs.
What is the difference between a DSM, DTM, and DHM?
A Digital Surface Model (DSM) represents the earth's surface and includes all objects on it. In contrast, a Digital Terrain Model (DTM) represents the bare ground surface without any objects like vegetation and buildings. A Digital Height Model (DHM) is another term used to refer to either a DSM or a DTM.
What is the accuracy of a Digital Elevation Model?
The accuracy of a Digital Elevation Model depends on the method used to gather the terrain data and the resolution of that data. In general, models generated from LiDAR data are considered to be highly accurate. However, the accuracy can vary depending on factors such as the quality of the original data, the density of sampling points, and the complexity of the terrain.
