  Facial motion tracking in head-mounted displays (HMD) has the potential to
enable immersive "face-to-face" interaction in a virtual environment. However,
current works on facial tracking are not suitable for unobtrusive augmented
reality (AR) glasses or do not have the ability to track arbitrary facial
movements. In this work, we demonstrate a novel system called SpecTracle that
tracks a user's facial motions using two wide-angle cameras mounted right next
to the visor of a Hololens. Avoiding the usage of cameras extended in front of
the face, our system greatly improves the feasibility to integrate full-face
tracking into a low-profile form factor. We also demonstrate that a neural
network-based model processing the wide-angle cameras can run in real-time at
24 frames per second (fps) on a mobile GPU and track independent facial
movement for different parts of the face with a user-independent model. Using a
short personalized calibration, the system improves its tracking performance by
42.3% compared to the user-independent model.
