To Define an Ellipsoid

You can create an ellipsoid from scratch or modify an existing ellipsoid and save it as a new one.

To define an ellipsoid

1. Click Map Setup tabCoordinate System panelCreateCreate Ellipsoid Definition. Find
2. In the Create Ellipsoid Wizard, enter a code and description for the ellipsoid .

   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 Coordinate System Library.

3. Under Ellipsoid Dimensions, do the following:
   • Specify whether to create a sphere or an ellipsoid.

     If you select Create An Ellipsoid, you must complete all four values. However once you enter Equatorial Radius and one other value, the remaining values are filled in automatically. If you select Create A Sphere, you must enter a value for Equatorial Radius only.

   • Enter a value for Equatorial Radius.

     This parameter specifies the equatorial radius in meters. The equatorial radius is also called the semi-major axis.

   • If you are defining an ellipsoid, rather than a sphere, specify one other parameter. AutoCAD Map 3D computes the other values based on the ones you enter.

     Inverse Flattening: Speciy the denominator of the flattening ratio. That is, if the flattening ratio is 1/x, specifies x.

     Polar Radius: Specify the polar radius in meters. The polar radius is also called the semi-minor axis.

     Eccentricity Squared: Specify the eccentricity as a real number.

4. Click Finish.