The definition of the coordinate system involves two vectors, the Principal Axis vector and the Orientation About Principal Axis vector. The coordinate system respects the plane formed by these two vectors and aligns with the Principal Axis.
Principal Axis
Use the Principal Axis category to define the X, Y, or Z axes (using Axis property) in terms of a:
Geometry Selection: You use this option to specify a geometry or mesh selection to define the direction of the Principal Axis. When selected, an associated Geometry property displays. You use the Geometry property to specify either one or more faces/element faces, two edges, two vertices, or two or three nodes.
Fixed Vector: Depending upon the Geometry Selection in the Origin category, this option preserves the current Geometry Selection without associativity. When a change occurs to the feature the axis will not update automatically to reflect that change.
Global X/Global Y/Global Z axis: These options force the axis to align to a global X, Y, or Z axis.
Hit Point Normal: This property aligns the axis along a normal vector that represents the normal direction of the local surface curvature of the hit point. You then select a point on the screen to define the Hit Point Normal and orient the primary axis. For information on creating a coordinate system aligned with the hit point, see Creating a Coordinate System Based on a Surface Normal.
Orientation About Principal Axis
Use the Orientation About Principal Axis Details category to specify the:
Axis property. Options include (default), , or .
Defined By property. Options include , , , , , and .
As above, when using the property, an associated Geometry property displays that you use to specify either one or more faces/element faces, two edges, two vertices, or two or three nodes.
Important: The setting leaves the orientation of the coordinate system unspecified. Review the values of the properties in the Directional Vectors category for the axis data being defined.