[Parameters: Topic='LAND SURFACE', Term='TOPOGRAPHY', Variable_Level_1='CONTOURS']
Digital Elevation Model Data from 7.5-Minute Quadrangle MapsEntry ID: 7_MIN_DEM
Abstract: Produced by the U.S. Geological Survey (USGS), the 7.5-Minute Digital
Elevation Model (DEM) data are digital representations of cartographic
information in a raster form. DEMs consist of an array of elevations for
ground positions at regularly spaced intervals. The data are produced in
7.5- by 7.5-minute blocks either from digitized cartographic map contour
overlays or from scanned ... National Aerial Photography Program (NAPP)
DEM data are stored as profiles in which the spacing of the elevations along
and between each profile is 30 meters. The number of elevations between
each profile will differ because of the variable angle between the
quadrangle's true north and the grid north of the Universal Transverse
Mercator (UTM) projection coordinate system.
DEM files may be used in the generation of graphics such as isometric
projections displaying slope, direction of slope (aspect), shaded relief
visualizations and terrain profiles between designated points. They may
also be combined with other data types such as stream location data and
weather data to assist in forest fire control or they may be combined
with remote sensing data to aid in the classification of vegetation.
Applications include: (1) modeling terrain gravity data for use in locating
energy resources, (2) determining the volume of proposed reservoirs, (3)
calculating the amount of material removed during strip mining, (4)
determining landslide probability, and (5) developing parameters for
As of November 14, 2006, the USGS no longer offers Digital Elevation Models. For the most recent elevation coverage, please see the National Elevation Dataset.
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ISO Topic Category
Access Constraints None
Use Constraints There is no guarantee of warranty concerning the accuracy of these data. Users should be aware that temporal changes may have occurred since the data was collected and that some parts of these data may no longer represent actual surface conditions. Users should not use these data for critical applications without a full awareness of their limitations. Acknowledgement of the originating agencies would be appreciated in products derived from these data. Any user who modifies the data set is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data set, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Please refer to http://www.usgs.gov/privacy.html for the USGS disclaimer.
Distribution Media: Digital Download from http://ned.usgs.gov
Role: DIF AUTHOR
Email: lta at usgs.gov
Information Systems Management U.S. Geological Survey EROS Center 47914 252nd Street
City: Sioux Falls
Province or State: SD
Postal Code: 57198-0001
U.S. Geological Survey (1993), Digital elevation models--data users guide 5: [Reston, Virginia], U.S. Geological Survey, 48
U.S. Geological Survey (1993), Standards for digital elevation models, National Mapping Division technical instructions: [Reston, Virginia], U.S. Geological Survey, [variously paged]
Extended Metadata Properties
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Creation and Review Dates
Last DIF Revision Date: 2013-06-03