50m Digital Terrain Model height data

A Digital Terrain Model (DTM) is a digital file consisting of a grid of regularly spaced points of known height which when used with other digital data, such as maps or orthophotographs can provide a 3D image of the land surface.

Key features

  • 50m regular grid
  • can be used in the digital creation of 3D mapping such as slope and aspect maps
  • using Geographical Information software, orthophotograph maps can be draped over a Triangular Irregular Network (TIN) derived from a DTM to create a 3D view of the land surface
  • DTM data can also be used in GIS to create thematic maps, grids and contours

Applications

  • planning
  • engineering
  • visualisation
  • height analysis
  • environmental impact analysis
  • sight lines
  • wind flow and pollution dispersion
  • soil erosion modelling
  • flow direction and accumulation
  • watershed delineation

Technical information

  • the DTM is created from stereo imagery in the orthophotography production process
  • all height measurements refer to elevation in metres above mean sea level at Belfast Lough
  • DTMs can be used to generate 3D TINs
  • the accuracy of the data is 1.0m RMSE (root mean square error)
  • area covered by each tile 20km x 20km
  • 50m DTM sample data
  • this data is now available under OSNI Open Data

 

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