A New Cubic B-Splines Design Method for Pen Input Environment

Pen-input is not a new means for CAD designers, in particular, in the concept design phase. Meanwhile, B-Splines are well known curve and surface design tool in 3D shape modeling in the final modeling stages in which neat curves and surfaces should be produced. In this paper, an intuitive B-Spline design method that can be used for the CAD systems both in conceptual modeling phase and in later design phases is proposed. Unlike the control point based interactive modification schemes for the Bspline curves and surfaces, we extend what has been called the “touchand-replace” method used for poly-line modification in the late 1980s to B-Splines; our approach uses successive pen strokes to modify the final shape of the existing B-Spline curves and surfaces. We also show related user test results in this paper as an empirical proof. key words: pen-input, B-Splines, concept design, computer aided design, pen strokes