DEM
Definition
A Digital Elevation Model (DEM) is a 3D representation of a terrain's surface that does not include any objects like buildings or vegetation. It presents the bare ground surface without any objects, similar to what it would look like if all the vegetation and man-made structures were removed. The DEM is created from terrain elevation data and is commonly used in Geographic Information Systems (GIS) for analyses and visualizations.
What is DEM?
Digital Elevation Model refers to a digital model or 3D representation of a terrain's surface. The data for DEMs is collected through remote sensing methods, such as Light Detection and Ranging (LiDAR) or via photogrammetry using stereo pairs from aerial photographs. The data is gathered and then processed to create a digital grid of the terrain.
DEM can be used in a variety of arenas including geographical and environmental studies, for instance, watershed delineation, landslide hazard analysis, habitat mapping, and in civil engineering to plan and design infrastructure.
FAQs
What is the difference between a DEM and a Digital Surface Model (DSM)?
A DEM represents the bare ground surface without any objects like buildings, vegetation etc., while a DSM includes all objects on it. A DSM, therefore, represents the earth’s surface with objects.
How is a DEM created?
A DEM is created using ground survey data, aerial data collected by unmanned aerial vehicles, satellites, or airborne LiDAR systems. This data is then processed, compiled, and digitized to form a 3D representation of the ground surface.
What is the significance of DEM in GIS?
DEM is a valuable tool in GIS because it enables a 3D representation of the ground surface for use in a wide variety of applications. These include terrain and surface analysis, 3D visualization, and other analyses that require an understanding of landscape features and elevation.
What are the types of DEM files?
DEM files can typically be found in two formats. They can be either raster, where the DEM consists of a grid of cells, each with its own elevation value, or TIN (Triangular Irregular Network) where elevation data is presented as triangles.
