Abstract:
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Cross contour surfaces are composed of sets of planar contours. They
are the natural output of surface extraction algorithms based on
contouring features in parallel image slices of volume models. They
are also suitable for the representation of CAD objects with tubular
elongated shapes such as pipes and tools. Rendering these surfaces
consists of tiling between successive contours, which is mainly a
problem of establishing correspondences: between successive contours
(branching) and also between vertices of consecutive contours
(triangles definition). Most of the existing algorithms solve these
problems by minimizing a distance function between vertices. However,
contours are generally composed of segments belonging to different
semantic regions that should not be mixed during tiling, as for
instance, functional regions of the brain and types of terrain in
elevation maps. A drawback of the existing distance based approaches
is that they may establish correspondences between points of different
segments. This paper proposes a representation model for surfaces
from cross contours composed of labeled segments. In addition, a
rendering algorithm of this model is described, that removes
undesirable tiles between segments of different labels. The proposed
method allows the tiling to be done on the fly, avoiding thus a double
representation of the surface (contours plus triangle mesh). It also
allows adaptive levels of resolution in the rendering. |