1. A method for segmenting medical images of a non-planar surface of an object, the medical images being available as three or four-dimensional image sets, the method comprising the following steps: detecting a surface boundary in three- or four-dimensional image data sets, which delimits the non-planar surface of the object, creating a model surface, which is spanned between the surface boundary, correcting the model surface by means of distance information, which contains information about distance(s) between the model surface and the non-planar surface of the object, until a corrected model surface is generated, wherein correcting the model surface by means of distance information is carried out by orienting a three-dimensional volume-rendering of the object essentially perpendicular or acute-angled to the model surface, wherein the volume renderer performing the volume rendering produces a depth-map, which is used to provide the distance information between the model surface and the non-planar surface of the object, and depicting the corrected model surface, wherein the correction of the model surface by means of the distance information is carried out iteratively, until the corrected model surface is generated, and the distance information is at least partially obtained along tilted vectors which are acute-angled to the model surface, wherein the three-dimensional volume-rendering of the object is then oriented essentially parallel to the tilted vectors.