2.3.3.3.47. NXcg_alpha_complex¶
Status:
base class (contribution), extends NXcg_primitive
Description:
Computational geometry of alpha complexes (alpha shapes or alpha wrappings) abou ...
Computational geometry of alpha complexes (alpha shapes or alpha wrappings) about primitives.
For details see:
https://dl.acm.org/doi/10.5555/871114 for weighted, and
https://doc.cgal.org/latest/Alpha_shapes_3 for 3D implementation of alpha shapes, and
https://doc.cgal.org/latest/Manual/packages.html#PkgAlphaWrap3 for 3D alpha wrappings
in CGAL, the Computational Geometry Algorithms Library respectively. As a starting point, we follow the conventions of the CGAL library.
In general, an alpha complex is a not necessarily connected or not necessarily pure complex, i.e. singular faces may exist. The number of cells, faces, and edges depends on how a specific alpha complex is filtered for lower-dimensional simplices. The fields is_regularized and regularization can be used to provide details about regularization procedures.
Symbols:
No symbol table
- Groups cited:
Structure:
type: (optional) NX_CHAR
Type of alpha complex following the terminology used by CGAL for now. ...
Type of alpha complex following the terminology used by CGAL for now.
Alpha_shape means meshes created using one of the alpha_shape algorithm. Alpha_wrapping means meshes created using the alpha_wrapping algorithm.
Any of these values:
convex_hull
|alpha_shape
|alpha_wrapping
regularization: (optional) NX_CHAR
Human-readable description about regularization procedures.
is_regularized: (optional) NX_BOOLEAN
Was the alpha complex regularized, i.e. have singular faces been removed, or not.
alpha: (optional) NX_NUMBER {units=NX_ANY}
The alpha parameter, i.e. the squared radius of the alpha-sphere ...
The alpha parameter, i.e. the squared radius of the alpha-sphere that is used when computing the alpha complex.
offset: (optional) NX_NUMBER {units=NX_LENGTH}
The offset distance parameter used when computing alpha_wrappings.
CG_POINT: (optional) NXcg_point
Point cloud serving as input for the computation of the alpha complex.
TRIANGLE_SOUP: (optional) NXcg_triangle
Triangle soup serving as input for the computation of the alpha complex.
ALPHA_COMPLEX: (optional) NXcg_triangle
Triangle mesh representing the output of the computation, i.e. the alpha complex.
TETRAHEDRALIZATION: (optional) NXcg_tetrahedron
Tetrahedra representing an interior volume of the alpha complex (if such exists).
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