by James Arvo and Kevin Novins. ACM Symposium on User Interface
Software and Technology (UIST) '00, pp. 73-80, ACM Press,
November 2000.
Abstract
We describe a new sketching interface in which shape recognition and
morphing are tightly coupled. Raw input strokes are continuously
morphed into ideal geometric shapes, even before the pen is lifted.
By means of smooth and continual shape transformations the user is apprised
of recognition progress and the appearance of the final shape, yet always
retains a sense of control over the process. At each time t the
system uses the trajectory traced out thus far by the pen coupled with
the current appearance of the time-varying shape to classify the
sketch as one of several pre-defined basic shapes. The recognition operation
is performed using shape-specific fits based on least-squares or
relaxation, which are continuously updated as the user draws. We
describe the time-dependent transformation of the sketch, beginning with
the raw pen trajectory, using a family of first-order ordinary
differential equations that depend on time and the current shape
of the sketch. Using this formalism, we describe several possible
behaviors that result by varying the relative significance of new
and old portions of a stroke, changing the "viscosity"
of the morph, and enforcing different end conditions. A preliminary
user study suggests that the new interface is particularly
effective for rapidly constructing diagrams consisting of simple
shapes.
Availability
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Last modified: December 2000.