A variety of real time constructive systems have been
developed to allow modeling through sketches. Igarashi et al
[3] developed a system where the user draws a 2D contour,
and through analysis of this contour the system inflates the
drawing into a 3D model; thereby constructing a 3D model
from a 2D drawing. Since a 2D sketch is naturally ambiguous
in 3D, such systems have complex heuristics for transforming
the 2D into the additional dimension. Other authors ([4], [5],
[6]) have also used sketches as the input for contour-driven
reconstruction and deformation.