Figure2: MultiresolutionIsoSurfaceExtraction: Wefirst
mark all points at a given resolution which have already
been evaluated as either occupied (red circles) or unoccu-
pied (cyan diamonds). We then determine all voxels that
have both occupied and unoccupied corners and mark them
as active (light red) and subdivide them into 8 subvoxels
each. Next, we evaluate all new grid points (empty circles)
that have been introduced by the subdivision. The previous
two steps are repeated until the desired output resolution is
reached. Finally we extract the mesh using the marching
cubes algorithm [44], simplify and refine the output mesh
using first and second order gradient information.