Social interactions by visual focus of attention in a three-dimensional environment

Abstract. In the human behavior analysis, the Visual Focus Of Atten-tion (VFOA) of a person is a very important cue. Its detection is difficult, though, especially in a unconstrained and crowded environment, typical of video surveillance scenarios. In this paper, we estimate the VFOA by defining the Subjective View Frustum, which approximates the vi-sual field of a person in a 3D representation of the scene. This opens up to several intriguing behavioral investigations. Here we propose the Inter-Relation Pattern Matrix, that suggests possible social interactions between the people present in the scene. Theoretical justifications and various experimental results substantiate the goodness of the analysis performed.