1. A method for determining the position of a plane of symmetry of a three-dimensional object, comprising the steps of: identifying at least one characteristic curve on a first two-dimensional mapping; morphing at least the first mapping into a second two-dimensional mapping; transferring the at least one characteristic curve to the second mapping; back-projecting the characteristic curve of the first and second mappings to obtain a three-dimensional course corresponding to the characteristic curve; and ascertaining the plane of symmetry of the three-dimensional object from the three-dimensional course.