Digital Elevation Models 

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As part of the digital orthophoto quad production process, the U.S. Geological Survey produces topographic information consisting of an array of regularly spaced elevations over a standard 1:24,000-scale quadrangle map sheet. Digital elevation models are particularly useful for GIS applications that are influenced by topography, such as drainage and flood potential, facility site decisions, viewshed analysis and solar or wind exposure issues. They are useful for general planning purposes rather than for site-specific projects.

Over the past 15 years, USGS DEMs have been produced using several different technologies. Some of the earlier methods (called "Level 1") had the potential to produce "banded" or "mottled" data. All of the DEMs available for Minnesota have now been produced using the most recent technology (called "Level 2") which does not have this problem. (Note:  USGS is investigating whether three quads are still Level 1:  Town Line Lake, Grand Portage and Grand Portage OE N.) The Level 1 files outside the Twin Cities metropolitan area were replaced by USGS; those within the metro area were redone by the Minnesota Department of Natural Resources. For more details, see description of corrected data problems.

The images above were both derived from digital elevation model data. They show the Mississippi River flowing southeast from downtown Minneapolis to Fort Snelling, the confluence of the Mississippi and Minnesota rivers, and the continued flow of the Mississippi northeast, then southeast through downtown St. Paul. The image on the left portrays elevation using a number of colored bands. On the right is a reflective image that depicts elevation through the bright spots and shadows cast by an imaginary sun. The resolution of the original digital elevation model data set is 30 meters.

• Corrected data problems
• U.S. Geological Survey national digital elevation model program
• National digital elevation model program metadata
• Downloading or ordering digital elevation model products

Related sites:

• High resolution elevation data for selected Minnesota counties from the Minnesota Department of Natural Resources
  • DEM
  • Contours
• USGS National Elevation Dataset, developed by merging the highest-resolution elevation data available across the United States into a seamless raster format (currently does not contain DNR's Level 2 DEMs but does contain some USGS 10-meter DEMs).
• Digital Elevation Committee of the Minnesota Governor's Council on Geographic Information including a status map of LiDAR elevation data efforts in Minnesota.
• USGS CLICK: Center for LiDAR Information Coordination and Knowledge
• Developing a High Resolution DEM and Floodplain Mapping Program:  June 2002 white paper from DNR - Division of Waters (715K, PDF).