1. A device for combining a current image (A) of an object ( 8 ) and a map image (B) of the dwell region ( 9 ) of the object ( 8 ), containing a data-processing system ( 5 ) that is arranged a) to estimate the position of the object ( 8 ) in relation to the map image (B), and b) to combine the map image (B) around the estimated position of the object ( 8 ) with the current image (A), the estimated position of the object in the map image (B) being brought into register with the actual position of the object in the current image (A), and only a section ( 7 ) of the map image (B) and/or of the current image (A) being used.