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DEM Enhancements

When processed correctly, digital elevation models (DEMs) can provide valuable geospatial information that might otherwise be missed. By extracting additional information from DEMs, you save both time and money when working on your next academic study, engineering project and/or spatial analysis. An Apollo Mapping representative can work with you to determine the correct enhancements for your specific project.

Enhancement Options

Here are some of the enhancements we can add to DEMs:

  • Contour Creation – conversion of raster DEMs to digital vectors ready for use in GIS
  • Breaklining – addition of elevation information along linear features with an abrupt change in gradient (such as a gulley, ridge or stream channel) that are often missed in automated DEM creation
  • Feature Extraction – utilizing multiple look angles offered by stereo data to develop accurate GIS layers, for instance of building footprints, edges of roads and tree crowns
  • Volume Calculation – determining accurate volumes of features on the earth’s surface, for example of coal piles and other mine tailings
  • Line of Sight Determination – mapping the various locations and/or features that are visible from a central point which is important in airport construction and wind/solar farm placement
  • 3D Modeling – creating a photo-realistic view of the earth’s surface and the features on it, often times with animated fly-throughs for efficient site planning and innovative multimedia presentations
What to ExpectUseful Info
A 3D fly-through from Arapahoe Basin to Keystone, Colorado using 1-meter imagery and a 10-m DTM (created in conjunction with our partner, Computer Terrain Mapping, Inc.).

Contour Intervals

We suggest extracting contours with a contour interval equal to a 4:1 or 5:1 ratio of the vertical accuracy. For example, a DEM with a vertical accuracy of 1 m LE90 should have contours with a 4 or 5 meter interval. An interval smaller than this often represents inaccurate (or over interpolated) data. Another reliable estimate of the maximum contour interval possible is the relative vertical accuracy of the elevation model.

Breaklines

Breaklining is also referred to as hydrographic enforcement. Surfaces with dramatic changes in elevation have important impacts on the flow of water through a channel as well as on line of sight modeling. As such, it is an important enhancement to consider for most engineering and hydrology projects.

Cut & Fill

Volume calculations (also referred to as cut and fill analysis) measure the amount of material required to move for the creation of roads, railways and canals. By modeling the amount of material to be moved, labor can be saved by roughly matching the cuts and fills to be completed.

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