Reference Topics > Specifying user coordinates
  
Specifying user coordinates
When calculating inertia, centroid, or principal axis, use the values for Centroid and Principal Axes (the defaults), or specify your own reference coordinates.
To specify your own coordinates:
1. Click Ref Coord. Creo Elements/Direct Modeling displays the reference coordinate dialog.
2. Specify an existing coordinate system. The origin and direction are derived from the selected coordinate system.
3. Specify an Origin. Select either a Point for the origin or the Centroid, which uses the centroid of the part as the origin.
4. Specify the Direction by selecting Principal Axes or by specifying your own Z Axis and X Axis.
◦ The principal axis of the part (in global coordinate system) is used as the axis of the reference coordinates.
◦ The Z and X axis use the measure direction decoder.