North American Vertical Datum of 1988
Geodesy | |
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68px | |
Fundamentals | |
Geodesy · Geodynamics Geomatics · Cartography | |
Concepts | |
Datum · Distance · Geoid Figure of the Earth Geodetic system Geog. coord. system Hor. pos. representation Map projection Reference ellipsoid Satellite geodesy Spatial reference system | |
Technologies | |
GNSS · GPS · GLONASS | |
Standards | |
ED50 · ETRS89 · GRS 80 NAD83 · NAVD88 · SAD69 SRID · UTM · WGS84 | |
History | |
History of geodesy NAVD29 | |
The North American Vertical Datum of 1988 (NAVD 88) is the vertical control datum of orthometric height established for vertical control surveying in the United States of America based upon the General Adjustment of the North American Datum of 1988.
The NAVD 88 was established in 1991 by the minimum-constraint adjustment of geodetic leveling observations in Canada, the United States, and Mexico. It held fixed the height of the primary tidal bench mark, referenced to the International Great Lakes Datum of 1985 local mean sea level height value, at Rimouski, Quebec, Canada. Additional tidal bench mark elevations were not used due to the demonstrated variations in sea surface topography, i.e., the fact that mean sea level is not the same equipotential surface at all tidal bench marks.
The NAVD 88 replaced the National Geodetic Vertical Datum of 1929 (NGVD 29), previously known as the Sea Level Datum of 1929. It is important to note that, while the computed elevation of some fixed point might differ depending on which datum is used, the elevation of that point relative to some other nearby point did not change with that datum change.
See also
- Altitude
- Geodesy
- National Geodetic Vertical Datum of 1929
- Sea Level Datum of 1929
- Topographic elevation
- Topography
- Reference ellipsoid
- Geoid
External links
- "United States Geological Survey home page". http://www.usgs.gov/.
- "U.S. National Geodetic Survey home page". http://www.ngs.noaa.gov/.
- "Geodetic Glossary". United States National Geodetic Survey. http://www.ngs.noaa.gov/CORS-Proxy/Glossary/xml/NGS_Glossary.xml.
- "Orthometric Height Conversion tool". United States National Geodetic Survey. http://www.ngs.noaa.gov/cgi-bin/VERTCON/vert_con.prl.ms:Datum Tegak Amerika Utara 1988