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National
Elevation Dataset (NED) a raster product created by the U.S. Geological
Survey (USGS). Drafted to provide National elevation data in a seamless form
to allow projection, elevation unit and consistent datum.
Performing edge
matching, artifact minimizing and fill silver areas of missing data were
also designed in the National Elevation Dataset product.
NED
elevation values converted to decimal meters are recognized as a consistent
unit of measure. The United States, Hawaii, Island Territories and Puerto
Rico all have a one arc-second resolution (approx. 30 meters), while Alaska
having a two arc-seconds resolution.
Designing NED consisted
of merging seamless dataset from multiple data sources, variety of
production methods and multiple resolutions from over 50,000 different DEM
data files.
National
Elevation Dataset raster data model is logically seamless but uses an
internal tile structure initially selected as a 1- by 1-degree area and
process identifies all existing DEM's available from data producers. NED
system filters production artifacts, and performs coordinate transformations
and any necessary datum conversions.
Processing
Procedures:
(courtesy of the USGS)
NED
Data Dictionary
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Entire
National Elevation Compressed on 2 DVD-ROM's
Entire
US Census Bureau Tiger 2004 Dataset on 1 DVD-ROM
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