3D skull and face similarity measurements based on a harmonic wave kernel signature

Abstract

Research regarding the similarity measurements of 3D craniofacial models (including 3D skull and face models) is an important research direction in fields such as archaeology, forensic science, and anthropology and represents a meaningful and challenging task. Its major challenges are the fact that 3D skulls are geometric models with multiple holes and complex topologies, there are facial expression changes on the 3D faces. Therefore, the general 3D shape similarity measurements, which are sensitive to boundaries and expression changes, make it impossible to simultaneously measure skull and face similarity. In this paper, we define a 3D signature to describe the pure intrinsic structure and distinguish the similar basic shape and complex topology of 3D skulls and faces: the harmonic wave kernel signature (HWKS). The HWKS is a point descriptor involving the Laplace–Beltrami operator, which is able to effectively extract geometrical and topological information from 3D skulls and faces. Based on the HWKS, we provide an effective pipeline for 3D skull and face similarity measurement by calculating the cosine distance between the HWKS values of 3D skulls and faces. By making comparisons with the wave kernel signature, the HWKS simultaneously describes both local and global properties of a shape. Results from a number of experiments have already shown that our framework is suitable for both measure 3D skull similarity and face similarity, and more importantly, measuring skull similarity and face similarity are two independent processes although using the same framework. By using the same measurement method for 3D skull similarity and face similarity, we observe an effective craniofacial relationship under unified metrics: The change rate of skull similarity is generally consistent with the corresponding face similarity, indicating the correlation between the shape of the 3D skull and its corresponding 3D face shape. And our experimental results show the rationality and effectiveness of this method, which refers to the previous researchers measure the similarity of the reconstructed face from the original skull to reflect the similarity of the original skull.