A method and apparatus for determining a three-dimensional orientation of a human head. The method includes first interposing a left and a right anthropological baselines on a patient's face, each anthropological baseline connecting an orbitale point and an auricular point on a corresponding side of the patient's face. A headgear unit having a pair of temple elements and a front housing rotatably attached to the temple elements, where the front housing includes at least two cameras and a 3D compass all movable within the front housing, is then positioned on a patient's head. Each of the two cameras is adjusted such that its view field picks up one of the two anthropological baselines on the patient's face. These view fields of the two cameras are then used to construct a Human Skull Base Plane as a plane formed by the left and right anthropological baselines when these anthropological baselines are parallel and aligned. The 3D compass is then positioned into a measuring plane coinciding with the Human Skull Base Plane, and is used to quantitatively measure a three-dimensional orientation of the patient's head at the time when the 3D compass is positioned within the measuring plane coinciding with the constructed Human Skull Base Plane.La présente invention concerne un procédé et un appareil permettant de déterminer une orientation tridimensionnelle d'une tête humaine. Le procédé consiste tout d'abord à interposer des lignes de base anthropologiques droite et gauche sur le visage d'un patient, chaque ligne de base anthropologique reliant un point orbital et un point auriculaire sur un côté correspondant du visage du patient. Un élément auxiliaire extra-oral présentant une paire d'éléments branche et un boîtier avant fixé rotatif aux éléments branche, le boîtier avant comprenant au moins deux caméras et un compas 3D entièrement mobiles à l'intérieur du boîtier avant, est ensuite positionné sur la tête d'un patient. Chacune des deux caméras est ajustée de sorte que leu
