The 3D mesh generator Vgrid
Vgrid is an octree-based 3D mesh generator. Contrary to the majority of mesh generators which are surface-based, Vgrid works directly on segmented image data, i.e. labelled voxels. Vgrid is able to produce hexahedral semi-structured grids (subsets of Cartesian grids) and tetrahedral unstructured meshes with possible local refinement.
Vgrid is available under the GPL at the Vgrid Homepage.
Vgrid was developed during the EU-project SimBio (1999-2003) at NEC Laboratories Europe (formerly CCRL) in St. Augustin near Bonn, Germany. It is based on prior work by Ulrich Hartmann and Frithjof Kruggel at the Max-Planck-Institute for cognitive neuroscience in Leipzig.
Vgrid is not developed further except very occasional bug fixes; its successor is Mesh & More.