A Study on Visual Focus of Attention Recognition from Head Pose in a Meeting Room

This paper presents a study on the recognition of the visual focus of attention (VFOA) of meeting participants based on their head pose. Contrarily to previous studies on the topic, in our set-up, the potential VFOA of people is not restricted to other meeting participants only, but includes environmental targets (table, slide screen). This has two consequences. Firstly, this increases the number of possible ambiguities in identifying the VFOA from the head pose. Secondly, due to our particular set-up, the identification of the VFOA from head pose can not rely on an incomplete representation of the pose (the pan), but requests the knowledge of the full head pointing information (pan and tilt). In this paper, using a corpus of 8 meetings of 8 minutes on average, featuring 4 persons involved in the discussion of statements projected on a slide screen, we analyze the above issues by evaluating, through numerical performance measures, the recognition of the VFOA from head pose information obtained either using a magnetic sensor device (the ground truth) or a vision based tracking system (head pose estimates). The results clearly show that in complex but realistic situations, it is quite optimistic to believe that the recognition of the VFOA can solely be based on the head pose, as some previous studies had suggested.