A computer-implemented medical method for pre-registering an anatomical body part of a patient's body, using the output of an augmented reality device having a distance measurement unit, the method comprising executing, on at least one processor of at least one computer, the following steps: a) a pre-registration of the anatomical body part being the result of determining the position of the anatomical body part in an augmented reality coordinate system associated with the augmented reality device based on the result of a distance measurement by the distance measurement unit, wherein the augmented reality coordinate system is a coordinate system in which positional values of augmentation information are defined for display by the augmented reality device; b) acquiring, based on a distance measurement by the distance measurement unit, surface detection data which describes a surface geometry of the anatomical body part; c) acquiring anatomical body part template data which describes a geometrical template of at least the surface geometry of the anatomical body part, wherein the anatomical body part template data is or has been generated from patient image data describing a medical image of the anatomical body part of the patient's body or from atlas data describing a generic model of at least the surface geometry of the anatomical body part or from synthetic template data describing a synthetic template of at least the surface geometry of the anatomical body part; d) determining a relative position between the augmented reality device and the anatomical body part based on the surface detection data and the anatomical body part template data; e) positionally registering the viewing direction of the augmented reality device with the tracking coordinate system based on the determined relative position between the augmented reality device and the anatomical body part, wherein at least one of the pre-registration or the position of a fine registration region is determined based on the registration of the viewing direction; wherein the method is characterised in that it comprises f) determining, based on the pre-registration, a position of the fine registration region of the anatomical body part in a real image acquired by the augmented reality device, wherein the fine registration region is an area which serves as an area for fine registration with a tracking coordinate system of a medical position tracking system using a pointing tool tracked by the position tracking system for identifying at least one point in the fine registration region to the position tracking system; and g) outputting, by the augmented reality device, augmentation information describing the position of the fine registration region. a) a pre-registration of the anatomical body part being the result of determining the position of the anatomical body part in an augmented reality coordinate system associated with the augmented reality device based on the result of a distance measurement by the distance measurement unit, wherein the augmented reality coordinate system is a coordinate system in which positional values of augmentation information are defined for display by the augmented reality device; b) acquiring, based on a distance measurement by the distance measurement unit, surface detection data which describes a surface geometry of the anatomical body part; c) acquiring anatomical body part template data which describes a geometrical template of at least the surface geometry of the anatomical body part, wherein the anatomical body part template data is or has been generated from patient image data describing a medical image of the anatomical body part of the patient's body or from atlas data describing a generic model of at least the surface geometry of the anatomical body part or from synthetic template data describing a synthetic template of at least the surface geometry of the anatomical body part; d) determining a relative position between the augmented reality device and the anatomical body part based on the surface detection data and the anatomical body part template data; e) positionally registering the viewing direction of the augmented reality device with the tracking coordinate system based on the determined relative position between the augmented reality device and the anatomical body part, wherein at least one of the pre-registration or the position of a fine registration region is determined based on the registration of the viewing direction; wherein the method is characterised in that it comprises f) determining, based on the pre-registration, a position of the fine registration region of the anatomical body part in a real image acquired by the augmented reality device, wherein the fine registration region is an area which serves as an area for fine registration with a tracking coordinate system of a medical position tracking system using a pointing tool tracked by the position tracking system for identifying at least one point in the fine registration region to the position tracking system; and g) outputting, by the augmented reality device, augmentation information describing the position of the fine registration region.