|
The South American Datum (SAD) is a regional geodesic datum for South America. It was established in Brazil by SIRGAS 2000, and was made official in 2005. == SAD69 == SAD was established as the regional geodetic datum for South America in 1969. This datum includes the Brazilian Geodetic System (''Sistema Geodésico Brasileiro'', or SGB), and uses the geoid as defined by the ellipsoid of the Geodetic Reference System - SGR-67 - accepted and recommended by the International Union of Geodesy and Geophysics at Lucerne in 1967. This ellipsoid is defined from the parameters: * Topocentric orientation: * * an axis of rotation parallel to the Earth's axis of rotation; plan meridian parallel to the Greenwich Meridian; * Topocentric orientation: considered planimetric datum, the Vertex Chuá chain triangulation of parallel 20° South, in Minas Gerais: * * geodetic latitude = 19° 45' 41.6527" S * * astronomical latitude = 19° 45' 41.34" S * * geodetic longitude = 48° 06' 04.0639" W * * astronomical longitude = 48° 06' 07.80" W * * Geodetic Azimuth = 271° 30' 04.05" SWNE; Astronomical Azimuth = 271° 30' 05.42" SWNE for VT-Uberaba * * geodetic undulation N = 0.0 meters * SGB Altimetry datum coincides with the equipotential surface that contains the mean sea level, defined by the tide gauge observations taken in Imbituba, on the coast at Santa Catarina. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「South American Datum」の詳細全文を読む スポンサード リンク
|