Services>DTM’s and DEM’s

Our Services DTM’s and DEM’s

Digital Terrain Models & Digital Elevation Models

Digital terrain models (DTMs), commonly referred to as digital elevation models (DEMs) are essentially the same; a digital representation of ground surface topography or terrain. Digital terrain models may be prepared in a number of ways, but they are frequently obtained by remote sensing rather than direct survey. One powerful technique for mapping digital terrain models is by using aerial photography (photogrammetry).

The quality of a digital terrain models, derived by photogrammetry, is a measure of how accurate elevation is at each point (absolute accuracy) and how accurately is the morphology presented (relative accuracy). Several factors play an important role for quality in DTM-derived products:

  • Experienced operators
  • Terrain roughness
  • Sampling density (elevation data collection method)
  • Scanning
  • Grid resolution or pixel size
  • Vertical resolution

Methods for Obtaining Elevation Data

Used to Create Digital Terrain Models

Survey Graphics utilise several methods for obtaining elevation data, used in creating digital terrain models:

  • Real Time Kinematic GPS
  • Stereo photogrammetry
  • Theodolite or total station
  • Doppler radar
  • Focus variation
  • Inertial surveys

Digital Terrain Model Applications

Common uses of digital terrain models include:

  • Extracting terrain parameters
  • Modelling water flow or mass movement (for example avalanches and landslides)
  • Creation of relief maps
  • Rendering of 3D visualizations
  • Creation of physical models (including raised-relief maps)
  • Rectification of aerial photography or satellite imagery
  • Reduction (terrain correction) of gravity measurements (gravimetry, physical geodesy)
  • Terrain analyses in geomorphology and physical geography
  • Geographic Information Systems (GIS)
  • Engineering and infrastructure design
  • Global positioning systems (GPS)
  • Line-of-sight analysis
  • Base mapping, flight simulation or surface analysis
  • Precision farming and forestry
  • Intelligent transportation systems (ITS)
  • Auto safety / Advanced Driver Assistance Systems (ADAS)