4.3.4.
Polar-/GPS-Transformation
With the menu Calculate
> Polar-/GPS-Transformation
a local transformation can be calculated using identical points.
To perform a local transformation choose the Input
> Coordinates menu and enter the coordinates and point numbers of the
control points.
When measuring the control points in the Input
> Measurements submenu, make sure to use the same point numbers as
entered before. Once you have measured your identical points, it is possible to
calculate a transformation. Therefore choose the Calculate
> Polar/GPS-Transformation menu.
First choose the kind of transformation with the Transf
> Change button. To perform a standard local adjustment use a
3-Parameter-Transformation without residual estimation.
The <Ctrl Pnt> button shows the
residuals for the control points. To add a control
point choose the button <Edit>
and activate on the checkbox CtrlPnt.
Use the button <Calculate>
to start the transformation for all points orientated on the chosen station. The
differences to the known coordinates are shown.
The
calculated transformation affects the user coordinates. It is saved with respect
to the station and is applied for all future measurements made on this station. GART-2000®
CE uses the
global 7-parameter transformation together with the projection chosen in Initial
> Constants > GPS and with the local transformation chosen here.
For the calculation of the transformation GART-2000®
CE uses the
measurements, not the user coordinates. For wrong saved points you should delete
the coordinate and the measurement before restarting the transformation.
For a new station the old transformation cannot be applied. Optionally, a new
transformation can be defined.
If you are working with a total station, you can display and monitor the
instrument error saved for a station via the button <Total Station>.
If the instrument errors have been incorrectly entered, these may be corrected.
Since the instrument errors play a part in the calculation of the station
coordinates, the calculation must be performed again following any correction by
clicking the button <Calculate>. In that case, all the measured and
previously calculated coordinates of the points on that station are computed in
the light of the new instrument data.