Announcing Stellar: A Tetrahedral Mesh Improvement Program

Stellar:  A Tetrahedral Mesh Improvement Program

Bryan Klingner and Jonathan Shewchuk
Department of Electrical Engineering and Computer Sciences
University of California, Berkeley


Stellar improves tetrahedral meshes so that their worst tetrahedra  
have high
quality, making them more suitable for finite element analysis.  Stellar
employs a broad selection of improvement operations, including vertex  
smoothing
by nonsmooth optimization, stellar flips and other topological  
transformations,
vertex insertion, and edge contraction.  If the domain shape has no  
small
angles, Stellar routinely improves meshes so that the smallest  
dihedral angle
is larger than 30 degrees and the largest dihedral angle is smaller  
than 140
degrees.

Features include a choice of several quality measures (both as objective
functions and for mesh statistics), control of tetrahedron sizes, and
transformations that improve the boundary of the mesh.  The last give  
you a
choice between flat surfaces (in which vertices are constrained to  
lie, so the
surface is improved without changing the domain shape) and curved  
surfaces
(where we optionally permit small changes of the domain shape if they  
give big
wins in mesh quality).

Stellar is written entirely in ANSI C, and relies only on standard C  
libraries.
It should compile on any POSIX-compliant system, and is known to  
compile on
Linux, Mac OS X, and Microsoft Windows.  Stellar's internal mesh data  
structure
is an implementation of Blandford, Blelloch, Cardoze, and Clemens'  
"Compact
Representations of Simplicial Meshes in Two and Three Dimensions".  For
geometric computations, it relies on our fast robust predicates  
code.  It is
available under the terms of the Berkeley Source Distribution (BSD)  
license.
It is accompanied by a (slightly unfinished) visualization program  
called Show
Me, which runs only under X Windows.

For software, documentation, and publications describing Stellar's  
algorithms,
please visit http://www.cs.berkeley.edu/~jrs/stellar/ .

Jonathan Shewchuk