I would compare Google Glass to a heads up display. No one that I have ever heard has called the HUD in an airplane or automobile an Augmented Reality device. To put computer graphics over the real world around you, you must track the location and orientation of the persons head. You also need to track the objects around the user so you can make the graphics overlay or interact with the real world realistically.
So, no head tracking, then no AR!
C'est magnifique, mais ce n'est pas l'Informatique. -- Bosquet [on seeing the IBM 4341]