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.
