1. A method for repositioning a crane, moving material handling equipment, and other numerically controlled devices, in a system including a camera imaging device, a storage data system, and an operator display screen by using an image taken of an object in the field of vision of the operator of the numerically controlled device as an aid, the method including a step to teach the system first by defining a child image from the imaging device, by forming a set of coordinates pertaining to the properties or state data for the numerically controlled device, the set of coordinates including a fixing point of the child image, and recording the child image, together with the co-ordinates in the data system, and the system later repositioning by comparing a real-time image from the imaging device with the child image stored in the data system, in order to determine the real-time position of the imaging device relative to the stored child image, by displaying the taught child image and real-time image on the operator display screen, and by superimposing a substantially straight line on the operator display screen depicting a measured distance between the fixing point of the child image and a fixing point of the real-time image, whereby the line is adapted to show the direction in which the numerically controlled device is repositioned, characterized in that, in the repositioning step, the image stored in the teaching step is sought when the coordinates of the real-time imaging device first comes close to the co-ordinate point of the child image stored in the data system.