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Elevation
The National Elevation Dataset (NED) is a seamless raster product primarily derived from USGS 10- and 30-meter Digital Elevation Models (DEMs), and, increasingly, from higher resolution data sources such as light detection and ranging (lidar), interferometric synthetic aperture radar (ifsar), and high-resolution imagery. NED data are available from The National Map Viewer as 1 arc-second (approximately 30 meters) for the CONUS, and at 1/3 and 1/9 arc-seconds (approximately 10 and 3 meters, respectively) for parts of the United States. NED resolution for Alaska is primarily 2 arc-seconds (approximately 60 meters) but is rapidly being replaced with 5-meter resolution ifsar data State-wide and lidar over select areas. Lidar point cloud data is available for download from Earth Explorer.
In response to growing needs for high-quality topographic data and for a wide range of other three-dimensional representations of the Nation's natural and constructed features, the National Geospatial Program has introduced the 3D Elevation Program (3DEP) initiative, the goal of which is to systematically collect enhanced elevation data in the form of high-quality lidar data over the conterminous United States (CONUS), Hawaii, and the U.S. territories. Ifsar data will be collected over Alaska, where cloud cover and remote locations preclude the use of lidar over much of the State. The 3DEP initiative will result in higher resolution and more accurate data as well as new products in the future.
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Image of an 'all-return lidar point cloud' featuring the USGS Earth Resources Observation and Science (EROS) Center in Sioux Falls, SD.
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Status & highlights
Latest National Elevation Dataset Update
The April, 2013 update of the National Elevation Dataset (NED) 1-, 1/3- and 1/9-arc-second collections was released on April 9, 2013. This marks the 71st update of the 1-arc-second layer since bi-monthly revisions began in June, 2000. This release incorporates 27,895 square miles of new light detection and ranging (lidar) data into the NED 1/9-arc-second layer. The NED 1- and 1/3-arc-second layers were updated with 54,761 square miles of migrated high-resolution source data and 13,700 square miles of interferometric synthetic aperture radar (ifsar) source data over Alaska. The April NED update includes topobathymetric (topobathy) data covering the North Carolina Outer Banks. All NED data are available via The National Map Viewer: htp://viewer.nationalmap.gov/viewer/.
The status graphic on the left (click for larger version) is one of several contained in the NED Release Notes for April, 2013 (PDF), which is published on a bi-monthly basis.
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Rogue River, Oregon Project
The Oregon Lidar Consortium's Rouge River project (donated to the USGS) is a fantastic example
of integration of multiple forms of remotely sensed data. Natural color orthoimagery (NAIP 2009)
was applied (conflated) to the lidar points which added RGB (red, green, blue) values to the point cloud data. This
combination makes for very impressive visualization and feature recognition. The dataset also has a
point density of 8 points per square meter, making it very dense and detailed: especially evident in the
tree canopy. This technique is even more powerful when acquisitions of orthoimagery and lidar are
done simultaneously, creating a temporally-matched, integrated dataset.
More information on DOGAMI's Rogue River project may be found at:
http://www.oregongeology.org/pubs/nr/press-release-2012-11-02.pdf
http://www.oregongeology.org/pubs/ldq/Lidar_Series_Index_Map_Rogue_Valley_2012.pdf
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Topobathy
The second set of topobathy data were released into the NED during the April, 2013 release. Topobathy data
are created by merging topography (land elevation) and bathymetry (water depth) into a seamless elevation
product useful for applications such as modeling sea level rise and storm surge. This dataset covers the
Outer Banks of North Carolina (shown to the left) and was constructed primarily from National Oceanic and
Atmospheric Administration (NOAA) bathymetry and USGS lidar-based topography. Additional datasets
were collected using a variety of technologies, including singlebeam and multi-beam bathymetry, Submetrix
Interferometric Sonar Bathymetry, and Shoaling Waves Experiment (SHOWEX) data. The lidar data were
collected during 2003 whereas the bathymetric data ranges from 1945 to 1996. This dataset was developed
in 2008 as a collaboration between the USGS Coastal and Marine Geology Program (CMGP) and the USGS
National Geospatial Program (NGP). In the next five years, the CMGP has plans to expand its research and
modeling along the northern Gulf of Mexico coastline, and San Francisco and Chesapeake Bays.
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Graphic representation of topo-bathymetric data for Mobile Bay, Alabama
Frame from lidar imagery video identifying the Mt. Tallac Fault, California.
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U.S. Department of the Interior |
U.S. Geological Survey
