A system for visually combining patient image data from transillumination and/or tomographic imaging methods and/or object image data with video images includes an image display device having an auto-stereoscopic monitor, at least one camera and a computer-assisted navigation system. The navigation system is operable to detect spatial positions of a part of the patient's body via a first tracking device attached to the body, and spatial positions of said image display device and/or said at least one camera via a second tracking device attached to the image display device or the camera, wherein the image display device and the at least one camera are assigned to each other and are formed as a portable unit.