Investigating the Midline Effect for Visual Focus of Attention Recognition

This paper addresses the recognition of people's visual focus of attention (VFOA), the discrete version of gaze indicating who is looking at whom or what. In absence of high definition images, we rely on people's head pose to recognize the VFOA. To the contrary of most previous works that assumed a fixed mapping between head pose directions and gaze target directions, we investigate novel gaze models documented in psychovision that produce a dynamic (temporal) mapping between them. This mapping accounts for two important factors affecting the head and gaze relationship: the shoulder orientation defining the gaze midline of a person varies over time; and gaze shifts from frontal to the side involve different head rotations than the reverse. Evaluated on a public dataset and on data recorded with the humanoid robot Nao, the method exhibit better adaptivity often producing better performance than state-of-the-art approach.