Unstructured Grid Generation Over Buildings Intersecting Terrain Data Using a Feature- Preserving Volumetric Technique

In this paper a new methodology to generate unstructured grids over intersecting objects is presented. It is based on the extraction of the zero-level iso-surface from a signed distance map defined on an adaptive background grid. The background grid points are first created following local object voxelizations and then connected using a Delaunay triangulation algorithm. A point enrichment strategy is then used to introduce new points into the background grid along detected surface features, i.e. ridges. The background grid is then adaptively refined close to the object surfaces and the distance to the surface function is computed. The final merged surface is obtained by extracting the zero-distance iso-surface. This watertight triangulation is then used as a support surface for unstructured grid generation from discrete data. These algorithms allow realistic modeling of a large number of complex engineering geometries using overlapping components defined discretely, i.e. via surface triangulations. This capability is very useful for grid generation starting from data originated in measurements or images.

[1]  R. Löhner.  Regridding Surface Triangulations , 1996 .

[2]  Arie E. Kaufman,et al.  Alias-Free Voxelization of Geometric Objects , 1999, IEEE Trans. Vis. Comput. Graph..

[3]  Rainald Löhner,et al.  A feature‐preserving volumetric technique to merge surface triangulations , 2002 .

[4]  Greg Turk,et al.  Simplification and Repair of Polygonal Models Using Volumetric Techniques , 2003, IEEE Trans. Vis. Comput. Graph..

[5]  Rainald Loehner,et al.  Some algorithmic problems of plotting codes for unstructured grids , 1989 .

[6]  S. Lo.  Automatic mesh generation over intersecting surfaces , 1995 .

[7]  Rainald Löhner,et al.  Surface triangulation over intersecting geometries , 1999 .

[8]  Juan R. Cebral,et al.  An Implicit Monolithic Time Accurate Finite Element Scheme for Incompressible Flow Problems , 2001 .

[9]  Tony DeRose,et al.  Mesh optimization , 1993, SIGGRAPH.

[10]  Rainald Löhner,et al.  From medical images to anatomically accurate finite element grids , 2001 .

[11]  Steven J. Owen,et al.  A Survey of Unstructured Mesh Generation Technology , 1998, IMR.

[12]  Rainald Löhner,et al.  Automatic unstructured grid generators , 1997 .

[13]  R Löhner,et al.  Merging of intersecting triangulations for finite element modeling. , 2001, Journal of biomechanics.

[14]  Jay P. Boris,et al.  Simulation of Fluid Dynamics Around Complex Urban Geometries , 2001 .

[15]  Rainald Löhner,et al.  Some useful data structures for the generation of unstructured grids , 1988 .

[16]  M. Berger,et al.  Robust and efficient Cartesian mesh generation for component-based geometry , 1998 .