Compressing hexahedral volume meshes
Unstructured hexahedral volume meshes are of particular interest for visualization and simulation applications. They allow regular tiling of the three-dimensional space and show good numerical behaviour in finite element computations. Beside such appealing properties, volume meshes take up huge amounts of space when stored in a raw format. In this paper, we present a technique for encoding the connectivity and geometry of unstructured hexahedral volume meshes. For connectivity compression, we generalize the concept of coding with degrees from the surface to the volume case. In contrast to the connectivity of surface meshes, which can be coded as a sequence of vertex degrees, the connectivity of volume meshes is coded as a sequence of edge degrees. This naturally exploits the regularity of typical hexahedral meshes. We achieve compression rates of around 1.5 bits per hexahedron (bph) that go down to 0.18 bph for regular meshes. On our test meshes the average connectivity compression ratio is 1:162.7. For geometry compression, we perform simple parallelogram prediction on uniformly quantized vertices within the side of a hexahedron. Tests show an average geometry compression ratio of 1:3.7 at a quantization level of 16 bits.
hexahedral meshes mesh compression degree coding volume data