UBC Theses and Dissertations
3D interaction studies using the shape-matching paradigm Jang, Stanley
At one time, 3D computer applications were only available on very specialized and very expensive workstations. However, technology on typical desktop computers has improved dramatically over the last decade, and is now capable of 3D graphics. If shrewd choices are made concerning the graphics hardware and software, a reasonably priced desktop computer will allow adequate real-time interaction for many applications. This thesis investigates some of these choices using a generalized program written to serve as an expandable testbed for evaluating some of the factors affecting user interaction in three dimensions. An important set of 3D tasks that occurs in applications such as computer aided design and computer animation is curve or surface design. Not only is the 3D environment an essential issue in efficiently completing these tasks, but so are the properties of the spline formulation and spline interaction technique chosen to represent the curves or surfaces. Previous work has shown that the B-spline formulation is quite effective for the interactive construction of 2D spline curves. A possible drawback in using the B-spline for the more difficult task of 3D curve construction is the fact that its control vertices may lie far away from the curve, making its manipulation unintuitive. 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 using the testbed to compare the interactive design of 3D curves using control vertex manipulation of B-spline curves and a particular type of direct manipulation of Bspline 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.
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