Boundaries > Create > From Spline creates a spline based on the user’s placement of control points, and converts the spline to a boundary.
Editing Mode group - specifies the action of the mouse in the Viewing Area
Define radio button - Each click of the mouse defines a point on the surface to which a spline will be fit. The preview of a boundary line appears in the Viewing Area as a white line that bisects triangles.
Edit radio button - activates the ability to Left-Drag a point to a new location in the Viewing Area.
Curve Definition group -
Remove Last Vertex button - removes the most recently defined point.
Control Points integer field (minimum 2, maximum equal to the current number of control points) - reduces the number of control points between the endpoints by redistributing remaining points evenly along the preview line.
Tension decimal field (0 to 1) - higher value yields a more stiff spline. Lower values yield a more flexible spline that adheres to the defined path more accurately.
Reset button - removes all control points.
OK button - converts the preview line to a boundary line if necessary, stores the new boundary or boundaries to the polygon object, and terminates the dialog.
Cancel button - terminates the dialog without saving boundaries to the polygon object.
Apply button - converts the preview line to a boundary line. Triangles that would have been bisected are subdivided so that the boundary does not cross any single triangle.