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Investigating the
Effectiveness of
Direct
Manipulation of
3D
B-Splines
Using the
Shape-Matching
Paradigm
Stanley
Jang,
Kellogg
S.
Booth,
David
R.
Forsey, and
Peter
Graf
Appeared in Graphics Interface '93 (pp. 97-106; Toronto, Ontario)
TR-92-40
ABSTRACT
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.