Motion Trajectory Grouping for Human Head Gestures Related to Facial Expressions

Abstract

The paper focuses on human head motion in connection with facial expressions for virtual-based interaction systems. Nowadays, the virtual representation of a human, with human-like social behaviour and mechanism of movements, can realize the user-machine interaction. The presented method includes the head motion because head gestures transmit additional information about the interaction’s situational context. This paper presents head motion analysis based on the rotation of rigid objects technique for virtual-based interaction systems. First, we captured the head gestures of a human subject, expressing three basic facial expressions. The proposed motion model was described using three non-deformable objects, which reflect the neck and head skeleton movement’s character. Based on the captured actions, the motion trajectories were analyzed, and their characteristic features were distinguished. The obtained dependencies were used to created new trajectories using piecewise cubic Hermite interpolating polynomial (PCHIP). Furthermore, the trajectories assigned to the rigid model have been grouped according to their similarities for a given emotional state. This way, using a single master trajectory and a set of coefficients, we were able to generate the whole set of trajectories for joint rotations of the head for the target emotional state. The resulting rotation trajectories were used to create movements on the three-dimensional human head.