Abstract: A method for determining the position data of a target object in a reference system from an observation position at a distance. A three-dimensional reference model of the surroundings of the target object is provided, the reference model including known geographical location data. An image of the target object and its surroundings, resulting from the observation position for an observer, is matched with the reference model. The position data of the sighted target object in the reference model is determined as relative position data with respect to known location data of the reference model.