About Creasing a Control Mesh
You can modify the shape of a Freestyle surface by applying a hard or a soft crease to the selected edges or vertices. Creasing adjusts the weight applied to edges and vertices so that the associated surfaces fit properly in the control mesh. You can apply the following types of creases to the selected edges or vertices:
• Hard crease—Sharpens the edges and generates a hard edge between the surfaces. For example, if you have selected a sphere as the primitive, you can convert it to a cylinder by applying 100% hard crease to its top and bottom faces.
• Soft crease—Creates smooth and tighter transitions between surfaces. For example, a 100% soft crease applied to a sphere gives it the effect of a fillet.