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19
18
Coordinate Systems
Coordinate Systems
Now highlight the duplicated system and tap the
edit
icon and choose
Adjust Grid-to-Ground & Rename
:
Adjust Grid-to-Ground & Rename
Screen
Tap the
Default
button
to change the coordinate
system name to the default name:
Tap the position icon
beside East Origin to set origin
point in the grid system for the transformation. Here the
base station coordinate is chosen from the points List:
By default the ground origin point will be populated with
the same coordinate and the
Scale Difference
is populated
with the grid-to-ground scale factor calculated from that
point. The scale factor rounded to the nearest part-per-
million (ppm) is automatically appended to the coordinate
system name:
You may also wish to round the scale difference to the
nearest ppm by tapping its button and entering that value.
In this screen options exist to enter a new factor as a Ratio
or Ppm:
The
Factors
button will allow you to use the CoGo Scale
Factor function to calculate a new scale factor if desired.
These settings will create an adjusted state plane coordinate
system scaled around the base station and the base station
coordinate will not change. This is useful for projects that
have ground distances as would be measured with a total
station and state plane coordinate system bearings since
the rotation is set to 0. The coordinates will be very close
to the real state plane system so that orthographic imagery
and state plane referenced contours or elevation models
can be loaded into your CAD drawings. You should be
cautious when giving these coordinates to others as they
may confuse them for real state plane coordinates. To
solve this problem you may wish to subtract 100,000 from
the
North
and
East Ground
coordinate values to create a
(100,000 100,000) offset from the real state plane system.
This can be done by tapping the
North Ground
and
East
Ground
boxes.
Tap the
button to add the current project’s name to
