The invention relates to a method and device for referencing between a data set, which describes geometrically the spatial model of a body, and the real physical environment in which the body is placed. A three-dimensional position reference body is used on the real body. The position reference body has one or more elementary bodies or markers whose 3-dimensional position can be detected with sensors and which define a fixed geometric reference with respect to the center of gravity of the body or to other body reference volumes. For registration, the position reference body and/or its elementary bodies are correlated in the data model and in the physical world.