1. A method for the registration of two 3D image data sets of an object to be imaged which is provided with a plurality of markers which are contained in the 3D image data sets, the method comprising the steps of: a) determining the positions of the markers in the 3D image data sets in a co-ordinate system associated with the relevant 3D image data set; b) determining at least one of a distance between two markers and an angle between two straight lines which intersect in one of the plurality of markers, each of the lines respectively defined by extending through another different marker of the plurality of markers; c) determining at least one of a corresponding distance and a corresponding angle in both of the 3D image data sets; d) determining the corresponding markers in each of the 3D image datasets on the basis of the at least one corresponding distance and angle; and e) determining a transformation rule for the transformation of one of one of the 3D image data sets to the co-ordinate system of the other 3D image data set.