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Transformation
1058
Characteristic
Description
1.
2.
3.
Positions and
The position and height transforma-
heights
tions are separated.
Use
When measurements are to be
forced to tie in with local existing
control in areas larger than
10 x 10 km.
Requirements
•
•
•
•
Area
Virtually any area as long as the local
coordinates are accurate.
Points and trans-
Identical with the Onestep transfor-
formation param-
mation.
eters
Points and height
Identical with the Onestep transfor-
transformation
mation.
Advantage
•
•
•
The WGS 1984 coordinates of
the common control points are
shifted closely to the local datum
using a given Classic 3D pre-
transformation. This Classic 3D
pre-transformation is typically a
rough transformation valid for
the country of the local datum.
The coordinates are projected
onto a preliminary grid, but this
time using the true map projec-
tion of the local points.
A 2D transformation is applied,
exactly as with the Onestep
transformation.
The position is known in
WGS 1984 and in the local sys-
tem for at least one point. Four
points or more are recommen-
ded to obtain higher redun-
dancy.
Parameters of the local ellipsoid.
Parameters of the local map pro-
jection.
Parameters of a pre-transforma-
tion.
Errors in height do not propagate
into errors in position since the
height and position transforma-
tions are separated.
If local heights have low accu-
racy or do not exist, a transfor-
mation of position can still be
calculated and vice versa.
The height points and position
points do not have to be the
same points.
Glossary
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