Image below demonstrates head rotation angles:
Returned detected face tag contains calculated yow and roll angles. There is no pitch angle calculation at the moment.
Yaw (rotation about Y axis), roll (rotation about Z axis) and pitch (rotation about X axis) angles are provided in degrees in range from -90 to 90. They are Tait-Bryan angles in right-hand 3D Euclidian space in image coordinate system (i.e. X axis is horizontal and points towards the right edge of the image, Y axis is vertical and points towards the bottom edge of the image and Z axis is perpendicular to the image and points away from the viewer). The rotation is reported as it would be performed about geometrical center of the head in the following order: roll (with positive direction being clockwise, towards the left shoulder of the subject), pitch (with positive direction being down) and yaw (with positive direction being to the left, towards the right shoulder of the subject). Remember that subjects are mirrored in the photo, i.e. subject’s left eye and left body parts are at the right and vice versa.