Digital elevation models

Learn about DSMs and DTMs.


A digital elevation model (DEM) is a representation of elevation data. DEMs are usually generated from remotely sensed data collected by satellites, drones, and planes.

Types of DEMs

A DEM can be a digital surface model (DSM) or a digital terrain model (DTM). Other derivative products of elevation models include slope, aspect, curvature, shaded relief, and normalized DSMs.

A DSM illustrates the Earth’s surface and all objects on it, while a DTM is a bare-earth model devoid of human-made and natural structures. A DTM can be derived from a DSM.

An image showing that DSMs include man-made objects and vegetation, while DTMs don't


A representation of the surface of the Earth with man-made objects and vegetation. DSMs are used for the following use cases:

  • Urban planning
  • Vegetation management
  • Runway approach zone encroachment
  • Orthorectification


A representation of the bare Earth elevation without man-made objects and vegetation. DTMs are used for the following use cases:

  • Reducing gravity measurements
  • Analyzing terrain
  • Gravimetry
  • Physical geodesy



What is a vertical datum in a DEM?

DEMs are referenced to a vertical datum. Depending on the model being used, a geodetic vertical datum takes a specific zero point, to which heights of various points will be referenced. The datum is needed for accurate measures of height above a surface.

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