Recognizing People’s Focus of Attention from Head Poses: a Study

This paper presents a study on the recognition of the visual focus of attention (VFOA) of meeting participants based on their head pose. Contrary to previous studies on the topic, in our set-up, the potential VFOA of a person is not restricted to other meeting the participants only, but include environmental targets (including a table, a projection screen). This has two consequences. First, it increases the number of possible ambiguities in identifying the VFOA from the head pose. Secondly, in the scenario we present here, full knowledge of the head pointing direction is required to identify the VFOA. An incomplete representation of the head pointing direction (head pan only) will not suffice. In this paper, using a corpus of 8 meetings of 10 minutes average length, featuring 4 persons involved discussing statements projected on a 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 such complex but realistic situations, it is can be optimistic to believe that the recognition of the VFOA can solely be based on the head pose, as some previous studies had suggested.