Leica GPS1200 Series Technical Reference Manual page 921

Determine Coordinate System - General
Transformation Characteristic
Onestep Principle
Positions and
heights
Use
Description
Transforms coordinates directly from WGS 1984 to
local grid and vice versa without knowledge about
the local ellipsoid or the map projection. Procedure:
1. The WGS 1984 coordinates are projected onto a
temporary Transverse Mercator projection. The
central meridian of this projection passes
through the centre of gravity of the common
control points.
2. The results of 1. are preliminary grid coordinates
for the WGS 1984 points.
3. These preliminary grid coordinates are matched
with the local grid control points in order to
compute the Easting and Northing shifts, the
rotation and the scale factor between these two
sets of points. This is known as a classic 2D
transformation.
4. The height transformation is a single dimension
height approximation.
The position and height transformations are sepa-
rated.
When measurements are to be forced to tie in with
local existing control. For example:
GPS1200 921