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Digital Elevation Models: Orthorectification, Obstruction Modeling And 3-D Point Clouds

Terrain modeling is a critical foundation to many geospatial applications such as orthoimagery generation and site modeling. CompassData generates high quality terrain models in a variety of formats and from a variety of sources. Our Digital Elevation Models may be used for orthorectification of satellite imagery, volumetric calculations and relief map generation. CompassData is also capable of creating Digital Elevation Models for use in the growing 3D mapping industry.  CompassData provides Digital Elevation Models as a stand alone product or as a portion of a ground control and imagery deliverable.

  • As a DigitalGlobe satellite imagery reseller, CompassData has ready access to a wealth of stereo imagery that can be used to construct elevation data.
  • As certified Trimble UX5 UAS operators and imagery processors, CompassData can generate very dense, detailed, terrain models from overlapping mono imagery.
Digital Elevation Models

Example Digital Surface Model created using a satellite stereo image pair (GeoEye 1 sensor).

A valuable aspect of LiDAR and UAS imagery is the creation of “point clouds”. The elevation points can have feature attributes and even color assigned to them. For instance the colorized point cloud (below) was generated from the overlapping mono images collected by a UAS. Not only do the points have x, y, z values, they typically can be assigned attributes such as “pine trees”, “scrub oak”, “cottonwood”, “grass”, “house”, which can be used to aid in analysis and for editing the elevation points to make a DEM.

 

Digital Elevation Models

Applications:

  • Floodplain Mapping; In September 2013 the Front Range of northern Colorado was severely impacted by what meteorologists termed the “thousand year rain”. CompassData was in the field weeks later collecting hundreds of control points for FEMA LiDAR mapping. The resulting DEMs will be used to re-establish flood plain models.
  • Volumetric calculations (how much material was removed from a pit mine over the past month?)
  • Elevation change detection (are there new buildings surrounding an airport?; or how much has the new highway overpass changed the drainage patterns?);
  • Aviation obstruction data (does the new cell phone tower potentially pose an obstruction at the regional airport?).
Digital Elevation Models
A digital elevation model or DEM is a digital model or 3D representation of the surface of an object, commonly the Earth or another planet, the moon, or an asteroid. DEMs are created from terrain elevation data. A Digital Surface Model (DSM) is a specific type of DEM in which the earth's surfaces including all inanimate objects are represented. A Digital Elevation Model (DEM) represents the bare ground surface without any objects like buildings and vegetation. Both types are useful for different applications. CompassData is well versed in the techniques used in DEM production such as land survey, photogrammetry, remote sensing and LiDAR data analyses. Contact us for more information on Digital Elevation Models.