Leica TPS1200 series Technical Reference Manual page 830

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Table of Contents

Determine Coordinate System - General

Requirements to deter-

mine a transformation

Requirements for

control points

Coordinate system

determination methods

To determine a transformation it is necessary to have common control points whose posi-

tions are known in both WGS 1984 coordinates and local coordinates. The more points that

are common between datums the more accurately the transformation parameters can be

calculated. Depending on the type of transformation used, details about the map projection,

the local ellipsoid and a local geoidal model may also be needed.

The control points used for the transformation should surround the area for which the

transformation is to be applied. It is not good practice to survey or convert coordinates

outside of the area covered by the control points as extrapolation errors may be intro-

When a geoid field file and/or a CSCS field file is used in the determination of a coordinate

system, the control points for the calculation must fall within the areas of the field files.

Two different methods for determining a coordinate system are available:

Coordinate system deter-

mination method

One point localisation

Characteristic

Number of control points

Transformation to use

Number of control points

One or more control points for

both the WGS 1984 and the

local datum.

Onestep, Twostep or Classic

3D, depending on number of

control points and available

information.

One control point for both the

WGS 1984 and the local