Defining a New Datum
Concept Procedure Quick Reference

To define a datum

  1. Click Map Setup tabCoordinate System panelDefine Global Coordinate System. At the Command prompt, enter ADEDEFCRDSYS. Select Define or Modify.
  2. On the General tab of the Define Global Coordinate System dialog box or the Modify Global Coordinate System dialog box, select Geodetic. Click Define.
  3. In the Datum Manager dialog box, click Define.
  4. On the General tab of the Define Datum dialog box, enter a code and description for the datum.

    The code must be unique within a category and across all coordinate systems and must not contain spaces. Only the following characters are valid: A-Z (upper or lower case), 0-9, dash, and underscore.

    AutoCAD Map 3D displays the description in the Datums list of the Datum Manager dialog box.

  5. Under Ellipsoid, select or define an ellipsoid to use for the new datum.

    For information about defining ellipsoids, see Defining an Ellipsoid.

  6. On the Datum Conversion tab, select a conversion technique from the Datum Conversion Technique list.
  7. Enter the appropriate conversion parameters for the conversion technique you selected.

    Under Conversion Parameters, under Vector Component Deltas To WGS-84 In Meters, enter the vector component deltas to WGS-84.

    If you use the Bursa/Wolfe or Seven Parameter Transformation conversion method, fill in all four edit boxes under Rotation Angle From WGS-84 In Arc Seconds.