Facial landmark extraction for lip tracking of patients with cleft lip using active appearance model

Abstract

Patients with cleft lip have trouble in communication because of facial disability resulting in both facial disfigurements and impairments in movement. Consequently, for individuals with facial functional impairments, lip tracking methods for analyzing these impairments are useful in treatment planning and diagnosis. In comparison with non-cleft control subjects, facial landmarks for lip tracking of patients with cleft lip need to be widely defined in the circumoral area in order to reflect an irregularly shaped mouth. In this paper, we discuss the idea of facial landmark extraction for lip tracking in patients with cleft lip. The idea is based on facial features, identified by using AAM (Active Appearance Model) algorithm for finding facial landmarks in the circumoral area. These landmarks are composed of the outer and inner contours of the mouth in the circumoral area. The inner contour of the mouth is represented as landmarks on the mouth. The outer contour of the mouth is divided into the upper outer contour and lower outer contour on the basis of the center line. Here, the center line is defined as an intersecting line which connects from the left corner to the right corner of the mouth. The distance from the lower lip to the jaw line in general is twice that from the bottom of the nose to the upper lip. Therefore, a set of artificial landmarks, the upper and lower outer contours, have been defined using a set of pre-determined distances. The distance from the lower lip to the lower outer contour used is twice that from the upper lip to the upper outer contour. Using these landmarks, we gathered objective measures of facial form in patients with cleft lip who have both form and functional deficits. All subjects were recruited from patients attending at the University of North Carolina School of Dentistry Craniofacial Center, Orthodontic, Pedodontic Clinics. Supported by: NIDCR GRANT #DE013814 & #DE019742. © 2011 Springer-Verlag.