2011

Global Coordinate System Manager Dialog BoxDialog Box
Modifying or Deleting a Datum
You can modify or delete any
datum (page 2059) that you define. You cannot
modify or delete predefined datums supplied with AutoCAD Map 3D.
If you modify or delete a datum that you have defined, you must also modify
or delete any coordinate systems that reference that datum.
See also:
■ Overview of Coordinate Systems (page 143)
■ Overview of Creating New Coordinate Systems (page 90)
■ Overview of Grid Data Files and Datum Shift Issues (page 103)
■ To define an ellipsoid (page 95)
To modify or delete a datum
1 On the General tab of the Define Global Coordinate System dialog box
or the Modify Global Coordinate System dialog box, select Geodetic.
Click Define.
Click Map Setup tab ➤ Coordinate System panel ➤ Define Global
Coordinate System.
Select Define or Modify.
2 In the Datum Manager dialog box, select a
datum (page 2059).
3 To modify the datum, click Modify.
To remove the datum, click Remove.
4 If you are modifying the datum, on the General tab of the Define Datum
dialog box, change the code and description for the datum.
To modify a predefined datum, you must change the code on the General
tab before you can change the other datum properties.
5 Under Ellipsoid, select or define an
ellipsoid (page 2062) to use for the datum.
For information about defining ellipsoids, see
Defining an Ellipsoid (page
95).
6 On the Datum Conversion tab, select a conversion technique from the
Datum Conversion Technique list.
Creating New Coordinate Systems | 99