Constructing dense correspondences for the analysis of 3D facial morphology

In this paper, we present a method for constructing dense correspondences between 3D open surfaces that is sufficiently accurate to permit clinical analysis of 3D facial morphology. Constructing dense correspondences between 3D models representing facial surface anatomy is a natural extension of landmark-based methods for analysing facial shape or shape changes. Compared to landmark-based methods, dense correspondences sample the entire surface and hence provide a more thorough description of the underlying 3D structures. The method we present here is based on elastic deformation, which deforms a 3D generic model onto the 3D surface of a specific individual. We are then able to construct dense correspondences between different individuals by analysing their corresponding deformed generic models. Validation experiments show that, using only five manually placed landmarks, approximately 95% of triangles on the deformed generic mesh model are within the range of ±0.5 mm to the corresponding original model. The established dense correspondences have been exploited within a principal components analysis (PCA)-based procedure for comparing the facial morphology of a control group to that of a surgically managed group comprising the patients who have been subject to facial lip repair.