This paper describes an algorithm to extract adaptive
and quality quadrilateral/hexahedral meshes directly from
volumetric data. First, a bottomup surface topology
preserving octreebased algorithm is applied to select a starting
octree level. Then the dual contouring method is used to extract a
preliminary uniform quad/hex mesh, which is decomposed into finer
quads/hexes adaptively without introducing any hanging nodes. The
positions of all boundary vertices are recalculated to approximate
the boundary surface more accurately. Mesh adaptivity can be
controlled by a feature sensitive error function, the regions that
users are interested in, or finite element calculation results.
Finally, a relaxation based technique is deployed to improve
mesh quality. Several demonstration examples are provided from a
wide variety of application domains. Some extracted meshes have
been extensively used in finite element simulations.
Paper Download
Adaptive and Quality Quadrilateral/Hexahedral Meshing from Volumetric Data (pdf) (ps), Proceedings of 13th International Meshing Roundtable, pp. 365376. Willamsburg, VA. September 1922, 2004.
A journal version of this paper (pdf) has been accepted in Computer
Methods in Applied Mechanics and Engineering (CMAME), 2005.
Related Links
Results
(Each image is linked to a higher resolution image.)
1. Adaptive quadrilateral and hexahedral meshes of a
biomolecule mAChE.
(a)  the quadrilateral mesh of the molecular
surface; (b)  the wireframe of the adaptive quadrilateral mesh of
the molecular surface; (c)  the adaptive hexahedral mesh of the
interior volume; (d)  the adaptive hexahedral mesh of the
exterior volume between the molecular surface and an outer sphere.
Finer meshes are generated in the region of the cavity, while
coarser meshes are kept in other areas. The cavity is shown in the
red boxes.
2. Quadrilateral and hexahedral meshes of the human head.
(a)  an adaptive quadrilateral mesh; (b)  the uniform hexahedral
mesh at a chosen starting level; (c)  an adaptive interior
hexahedral mesh controlled by the feature sensitive error
function; (d)  an adaptive exterior hexahedral mesh controlled by
the feature sensitive error function.
3. Quadrilateral and hexahedral meshes of the knee.
(a)  an adaptive quadrilateral mesh; (b)  the uniform hexahedral mesh at
a chosen starting level; (c)  an adaptive hex mesh controlled by
the feature sensitive error function; (d)  all the hexahedral
elements are refined.
4. Quadrilateral and hexahedral meshes are extracted from a
CTscanned volumetric data (UNC head).
(a)  the quadrilateral mesh of the skin; (b)  the hexahedral mesh of the volume inside
the skin; (c)  the quadrilateral mesh of the skull isosurface;
(d)  the hexahedral mesh of the skull.
5. Quadrilateral meshes of a bubble model.
(a)  the uniform
mesh at a chosen starting level; (b)  an adaptive mesh controlled
by finite element solutions (deformation); (c)  a mesh generated
by refining all the boundary elements.
6. Sharp features are preserved.
From left to right: an adaptive quad mesh of a mechanical part; an adaptive hex mesh of a
mechanical part; an adaptive quad mesh of a fandisk, an adaptive
hex mesh of a fandisk.
