1. A method for registering an image data set for visualizing internal areas of the body, said method comprising: determining a relative position of (i) an imaging device, and (ii) an external body part associated with an internal area of the body by: providing the external body part with markings; moving the imaging device from an initial position into one or more positions in which the markings appear in a defined position with respect to each other; and recording the movement of the imaging device; producing an image data set for the internal area of the body using the imaging device, wherein the image data set does not include data on the external body part; determining a spatial position of the external body part; and registering or assigning the image data of the internal area of the body with respect to the spatial position of the external body based on the relative position between the imaging device and the external body part.