Table 1: Information regarding calculated facial features.

Name Notation Description

Mouth outer Sum of the Euclidean distance between the mouth contour landmarks and the anchor landmarks. It monitors the zygomatic muscle.
Mouth corner Sum of the Euclidean distance between the mouth corner landmarks and the anchor landmarks. It monitors the zygomatic muscle.
Eye area Area of the regions bounded by the closed curves formed by the landmarks in contour of the eyes. It monitors the orbicularis oculi muscle.
Eyebrow activity Sum of the Euclidean distance between eyebrow landmarks and the anchor landmarks. It monitors the corrugator muscle.
Face area Area of the region bounded by the closed polygon formed by the most external detected landmarks.
Face motion Average value of the Euclidean norm of a set of landmarks in the last frames. It describes the total distance the head has moved in any direction in a short period of time.
Facial COM Average value of all detected landmarks. It describes the overall movement of all facial landmarks.