Freeform extrusion by sketched input

This paper presents a sketch based mesh extrusion method, which is useful for intuitive, efficient geometric modeling of freeform polygonal objects. With our method, the user can extrude either a closed or open surface from the surface or the boundary of a given mesh by sketched input. Thus, compared to earlier methods, our method provides more flexibility for solving surface modeling problems. Our mesh extrusion algorithm consists of four steps: 1) create a base curve; 2) project extruding strokes; 3) sweep a base curve; and 4) sew adjacent curves. At the end of this paper, examples of our mesh extrusion implementation are shown to demonstrate its functionality. Our freeform extrusion has been implemented as a part of our sketch based modeling system, and the mesh extrusion can be completed in real-time on a standard PC.