Free–Form Strokes
In recent years, the use on free–form strokes for creating 2D
free–form objects has become popular.
In 1994 (Hsu & Lee 1994) presented an animation system
for producing 2.5D animations using skeletal strokes as
the basic primitive. In their paper, skeletal strokes can be
regarded as a realization of the brush and stroke metaphor
using arbitrary pictures and its deformations as ink. Since
any arbitrary picture can be defined to be a skeletal stroke,
a huge variation in styles is possible. However, the animator
still has to cope with a lot of additional work (providing
input images and deforming images (Hsu, Lee, & Wiseman
1993)) in comparison with traditional animation.
More recently, (Vansichem, Wauters, & Van Reeth 2001)
proposed an approach for drawing and manipulating stylized
curves without the need to explicitly manipulate (i.e. point,
click and drag) control points of underlying splines. Their
approach generates curves on–the–fly by processing (pressure
sensitive) stylus data at real–time. This simplifies the
interaction drastically because the animator can exploit direct
manipulation tools on the curves themselves.
We use a similar technique as described by (Vansichem,
Wauters, & Van Reeth 2001) because this comes very close
to the sketching method that traditional animators tend to
use.