Investigating the Effectiveness of Direct Manipulation of 3D B-Spline Curves Using the Shape-Matching Paradigm

B-splines are one of many spline formulations for representing smooth curves. These formulations are found in a variety of applications, including interactive curve design. Previous research has shown that the B-spline is an effective formulation for this setting. However, a possible drawback for the novice user in using the B-spline is the fact that control vertices may lie far away from the curve, making its manipulation unintuitive. This problem is compounded in three dimensions. A direct manipulation technique, allowing a curve to be manipulated with points that lie on the curve itself, offers an alternative to control vertex manipulation. An experiment was conducted to compare the interactive design of 3D curves using control vertex manipulation of B-spline curves and a particular type of direct manipulation of B-spline curves. The results of the experiment revealed that direct manipulation was significantly faster than control vertex manipulation, without sacrificing accuracy in the shape of the final 3D curve. A general testbed designed for this investigation and related studies of 3D interaction techniques was used to conduct the experiment.