Geographic Coordinate System Setup
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Geographic Coordinate System Setup
This dialog is used to set up a Geographic Coordinate System. You can create one from scratch or modify an existing Geographic Coordinate System. To modify an existing Geographic Coordinate System use the "Edit" button.
Name
The name of the coordinate reference system. This can be edited if custom, or by clicking the Edit button.
Datum
The name of the datum. This can be edited if custom, or by clicking the Edit button.
Ellipsoid
Use the combo box to select a different ellipsoid or modify the parameter values to create a custom ellipsoid.
You can also change the units using the combo box which affects both the storage and display of the parameter data.
The custom rules above apply for any type of editing.
The parameter table contains the following parameters:
- Semi-major axis (a) - Length in linear units of the semi-major axis (called a) parameter of the ellipsoid
- Semi-minor axis (b) - Length in linear units of the semi-minor axis (called b) parameter of the ellipsoid
- Inverse flattening (1/f) - Dimensionless inverse flattening (called 1/f) parameter of the ellipsoid
- Linear unit - This is the length unit of the ellipsoid's parameters a and b
If the Semi-major axis or Semi-minor axis values are changed, the Inverse flattening will automatically update.
If the Inverse Flattening is changed, the Semi-minor axis value will automatically update.
If any of these value are manually changed, you are creating a custom ellipsoid, which will result in the Ellipsoid, Datum and Name fields having Custom appended as a suffix (if the name is not already a custom name).
Prime Meridian
Use the combo box to select a different prime meridian or modify the parameter values to create a custom prime meridian.
You can also change the units using the combo box which affects both the storage and display of the parameter data.
The custom rules above apply for any type of editing.
The parameter table contains the following parameters:
- Longitude - Longitude of Prime Meridian relative to Greenwich, a town in the United Kingdom.
- Angular unit - This is the angle related unit for the longitude.
Edit
The Edit button can be used to customize a built-in Geographic Coordinate System.
It will allow editing of all fields and removes the EPSG codes.