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Requirements for
control points
Coordinate system
determination methods
Determine Coordinate System - General
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-
duced.
•
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
Normal
One point localisation
Characteristic
Number of control points
needed
Transformation to use
Number of control points
needed
GPS1200+
Description
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
datum.
942
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