Search results
Results From The WOW.Com Content Network
Datum Shift Between NAD 27 and NAD 83. A point having a given latitude and longitude in NAD 27 may be displaced on the order of many tens of meters from another point having the identical latitude and longitude in NAD 83, so it is important to specify the datum along with the coordinates.
Magnitude of shift in position between NAD27 and NAD83 datum as a function of location. Grid-based transformations directly convert map coordinates from one (map-projection, geodetic datum) pair to map coordinates of another (map-projection, geodetic datum) pair.
For example, converting from NAD 27 to NAD 83 is performed using NADCON (later improved as HARN), a raster grid covering North America, with the value of each cell being the average adjustment distance for that area in latitude and longitude. Datum conversion may frequently be accompanied by a change of map projection.
Thus the state plane coordinate system is still useful. Originally, the state plane coordinate systems were based on the North American Datum of 1927 (NAD27). Later, the more accurate North American Datum of 1983 (NAD83) became the standard (a geodetic datum is the way a coordinate system is linked to the physical Earth). More recently there ...
The National Transformation format has been developed by Natural Resources Canada's Geodetic Survey Division for conversions between NAD27 and NAD83 but it has been adapted to several other countries, such as Australia, Austria, [3] Belgium, [4] Brazil, Canada, France, Germany, New Zealand, Portugal, Romania, [5] South Africa, Spain, Switzerland, Venezuela [2] and the United Kingdom.
The NAD27 was later supplanted by the North American Datum of 1983 (NAD83), which was formally adopted by the United States in 1989 and Canada in 1990; the new system moved the reference point to a point in the Earth's core, and the Meades Ranch marker lost its special significance to the geodetic datum system.
BeiDou Coordinate System, China Terrestrial Reference Frame (CTRF) 2000 = ITRF97 at epoch 2000.0; own implementation. GLONASS PZ-90.11 is nominally its own system, but is quite close to ITRF and uses many of the same techniques. [2] National systems: United States: WGS 84 (see above); domestic use is mainly based on NAD 83 instead.
ISO 6709, Standard representation of geographic point location by coordinates, is the international standard for representation of latitude, longitude and altitude for geographic point locations. The first edition ( ISO 6709:1983 ) was developed by ISO/IEC JTC 1 /SC 32.