Hierarchical Iso-Surface Extraction

The extraction and display of iso-surfaces is a standard method for the visualization of volume data sets. In this paper we present a novel approach that utilizes a hierarchy on both the input and the output data. For the generation of a coarse base mesh, we construct a hierarchy of volumes and extract an iso-surface from the coarsest resolution with a standard Marching Cubes algorithm. We addi- tionally apply a simple mesh decimation algorithm to improve the shape of the triangles. We iteratively fit this mesh to the iso-surface at the finer volume levels. To be able to reconstruct fine detail of the iso-surface we thereby adaptively subdivide the mesh. To evenly distribute the vertices of the triangle mesh over the iso-surface and generate a triangle mesh with evenly shaped triangles, we have in- tegrated a mesh smoothing algorithm into the fitting process. The advantage of this approach is that it generates a mesh with subdivi- sion connectivity which can be utilized by several multiresolution algorithms such as compression and progressive transmission. As applications of our method we show how to reconstruct the surface of archaeological artifacts and the reconstruction of the brain sur- face for the simulation of the brain shift phenomenon.