What is the projection, horizontal datum, vertical datum, and resolution for a USGS digital elevation model DEM?

Projection:  3DEP DEMS have different projections/coordinate systems depending on the product:

  • 1/3-, 1-, and 2-arc-second (also the discontinued 1/9-arc-second) DEMs are not projected.  They are all in geographic coordinates (latitude/longitude).
  • 5-meter DEMs (Alaska only) are Alaska Albers Equal Area.
  • 1-meter DEMs are in Universal Transverse Mercator (UTM).
  • Original Product Resolution (OPR) DEMs – projection varies.
  • The coordinate system and projection information for ALL DEMs are in each DEM file header; GIS software should detect them automatically.

Horizontal Datum:  The North American Datum of 1983 (NAD83)  

Vertical Datum:  Typically the North American Vertical Datum of 1988 (NAVD88), although the National Geodetic Vertical Datum of 1929 (NGVD29) and local reference datums are used in some areas outside of the conterminous United States. For Hawaii, Puerto Rico, U.S. Virgin Islands, and Pacific Island territories, the vertical datum is typically referenced to local mean sea level.    

Resolution:  The conterminous United States is available at horizontal resolutions of  

  • 1-arc-second (~30 meters):  full coverage  
  • 1/3-arc-second (~10 meters): full coverage   
  • 1/9-arc-second (~3 meters): partial coverage  
  • 1-meter: partial coverage   

Learn more: 

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If you think you’ve found an error in USGS elevation data, please send an email to tnm_help@usgs.gov . We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors are of concern to us. We are working to correct or...
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PubTalk 11/2010 — Silicon, Software, and Science

Monitoring the Earth's Landscape with Low-Cost High-Tech

by Rian Bogle, Remote Sensing Specialist

 

  • The USGS is one of the world's largest providers of remote sensing data, employing the best tools and techniques to expand our knowledge of the Earth.
  • Working with low-cost field and aerial imaging technologies,