1. Method for visualizing surface-like structures in volumetric data sets, wherein the visualization is determined by a set of external parameters comprising position coordinates and/or directions defining the visualization, the method comprising the steps of a) defining local coordinate systems at sample points of said volumetric data set, b) calculating gradient vector components (Gai, Gbi, Gci) within said local coordinate systems of said sample points, c) transforming said external parameters from a global coordinate system into said local coordinate systems at selected sample points or at points of a reference grid, d) using said gradient vector components for calculating a surface normal at a given position of said volumetric data set, and e) calculating external parameters from said global coordinate system at said given position by using the transformed external parameters of said local coordinate systems at said selected sample points or points of a reference grid.