Boundaries > Create > By Crease Angle creates a boundary line between every pair of adjoining polygons whose normals differ by a specified angle or more. This function works in all selected areas, or on the entire object if no areas are selected.
Angle decimal field (5 to 180) - the lowest difference between normals of adjoining triangles that will generate a red boundary line. 5 creates a red boundary line between triangles whose normals differ by 5 degrees or more. 90 creates a boundary line between any two polygons that meet at a right angle. 179 creates boundary lines on razor-sharp edges. 180 generates no boundary lines because the normals of two adjoining triangles cannot differ by 180 degrees.
Include Natural Boundaries checkbox - specifies whether to show a red boundary line on every natural boundary (regardless of Angle). Natural boundaries exist even if not shown.
Min. Length field - After Angle is applied, the algorithm then removes contiguous sets of boundary lines whose collective length does not equal or exceed this value.
OK button - saves the new boundaries to the polygon object and terminates the dialog.
Cancel button - terminates the dialog without saving new boundaries to the object.