“…Through suitable approximations of the data, they are also able to extract approximate isosurfaces with varying complexity. The various methods mainly differ in the type of hierarchy and interpolation, such as octrees [24], red tetrahedral refinement [8,10,29], tetrahedral bisection [5-7, 20, 32], hierarchical Delaunay triangulations [2], or wavelet techniques [25]. With the help of bounds for the minimum and maximum data value inside each subdomain, the scanning of empty regions is also avoided.…”