BIB-VERSION:: CS-TR-v2.1
ID:: ncstrl.utah_cs//CSTD-97-004
PAGES:: 154
ENTRY:: January 12, 1998
TITLE:: Representation of and Modeling with Arbitrary Discontinuity Curves in
Sculptured Surfaces
AUTHOR:: Ellens, Marc S.
ABSTRACT:: Representing data after it has undergone a fundamental topological
change, such as cracking, ripping or folding, or after the introduction of
arbitrary feature curves as happens during the creation of darts, corners, or
fractures, continues to be a significant challenge.  Ideally, the
representation is modified without having to reformulate the representation
entirely.  If the original model is composed of faceted polyhedra, it is
possible to do this.  However, many models today are being represented by
smooth parametric tensor product surfaces such as B-splines, which do not
easily support arbitrary discontinuities.  During the design process, when
discontinuities are introduced, such models are often tessellated into
triangles, which would henceforth be the model's representation. In this case,
the resulting model is often not useful for further design. This thesis
introduces an extension of the B-spline surface representation, called the torn
B-spline surface.  The torn B-spline representation provides flexibility not
previously found in similar parametric surfaces by incorporating tear curves,
crease curves and other arbitrary C-1 feature curves into the representation
itself.  Simulation events or other design processes which result in
discontinuities in the representation do not necessitate a change in
representation, and it is possible to use B-spline design methods on the
resulting torn surface model.  This makes design with discontinuities more
viable.  The representation and associated algorithms used to support it are
introduced, as well as some higher order design operators which take advantage
of this representation and some example applications.
DATE:: January 12, 1998
END:: ncstrl.utah_cs//CSTD-97-004