Leica GPS1200+, Technical Reference Manual

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Determine Coordinate System - General 932
39 Determine Coordinate System - General
39.1 Overview
Description GPS measured points are always stored based on the global geocentric datum known as
WGS 1984. Most surveys require coordinates in a local grid system, for example, based on
a country’s official mapping datum or an arbitrary grid system used in a particular area such
as a construction site. To convert the WGS 1984 coordinates into local coordinates a coor-
dinate system needs to be created. Part of the coordinate system is the transformation used
to convert coordinates from the WGS 1984 datum to the local datum.
The Determine Coordinate System application program allows:
• the parameters of a new transformation to be determined.
• the parameters of an existing transformation to be recomputed.
Transformations A transformation is the process of converting coordinates from one geodetic datum to
another.
Requirements
• Transformation parameters.
• In some cases a local ellipsoid.
• In some cases a map projection.
• In some cases a geoid model.