A method for incorporating tomographically obtained image data from a patient into a system for surgical planning and/or intraoperative navigation involves tomographic image data or image data obtained by X-ray recordings from at least one defined body area of the patient by at least one first recording appliance, wherein a first reference body having at least one surface is arranged on the patient and is recorded by the first recording appliance at the same time. The recorded image data representing the first reference body are compared with known geometric data from the first reference body in order to obtain distortion information. The recorded image data are equalized by a computation unit based on the distortion information to obtain equalized image data which have further image data from the same body area superimposed to obtain superimposed image data that is presented on a display.