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Representation and Retrieval of
Mesh Data for regular Meshes
© 2005
Next Dimension Imaging
Most
regular surface meshes can be defined by a single 2-dimensional matrix of spatial
coordinates. If n is the number of stacks and m is the number of slices or
profile points the matrix has the dimension n x m.
If a
mesh represents an object with one or more cutout-s (like the surface mesh of a
glyph 'B', which has 2 coutout-s) multiple matrices are necessary to define the
object. If c is the number of
cutout-s, c+1 matrices are required. All matrices have the same height
(dimension n) the with however (dimension m) varies, since the contours of the
outline and the contours of the cutout-s have in general a different number of
coordinates.
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The
MORE engine returns the mesh definition in the form of loop index lists which
are called stack loops. A single stack loop corresponds to a row in the
coordinate matrix. Indexes are in reference to the mesh coordinate
list.
The
displayed surface mesh of glyph '5' has one stack and 112 profile points. MORE
will report two planar stack loops, which correspond to the contour loops
of the front face and the back face. Each loop is defined by 112 points. Since the
object has no cutout-s, the object has only one coordinate matrix or loop stack.
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The
solid glyph '8' has three matrices or loop stacks, one for each front face
contour. Each loop stack contains two loops of identical length one for the
front face and one for the back face. The loop length however, is different
in each loop stack. The first loop stack represents the outline of the
longest outer loop (major contour). The other two loop stacks contain the
shorter loops of the two cutout-s. |
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This torus represents a cyclic solid object with 12 stacks and 24
slices. MORE will report 12 loops of length 24 in one loop stack. Since the
object is solid, it has no contour loops.
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This mesh of a dinosaurs eye is a fragment with 17 stacks and 16 slices.
MORE will report 17 loops of length 16, two contour loops
of length 16 in one loop stack.
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