title: F-formation detection: individuating free-standing conversational groups in images.
abstract: Detection of groups of interacting people is a very interesting and useful task in many modern technologies, with application fields spanning from video-surveillance to social robotics. In this paper we first furnish a rigorous definition of group considering the background of the social sciences: this allows us to specify many kinds of group, so far neglected in the Computer Vision literature. On top of this taxonomy we present a detailed state of the art on the group detection algorithms. Then, as a main contribution, we present a brand new method for the automatic detection of groups in still images, which is based on a graph-cuts framework for clustering individuals; in particular, we are able to codify in a computational sense the sociological definition of F-formation, that is very useful to encode a group having only proxemic information: position and orientation of people. We call the proposed method Graph-Cuts for F-formation (GCFF). We show how GCFF definitely outperforms all the state of the art methods in terms of different accuracy measures (some of them are brand new), demonstrating also a strong robustness to noise and versatility in recognizing groups of various cardinality.
authors.affiliation: Institute of Cognitive Science and Technologies (ISTC), Italian National Research Council (CNR), Trento, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Setti
authors.affiliation: Department of Computer Science, University College London, London, UK.
authors.forename: Chris
authors.initials: C
authors.lastname: Russell
authors.affiliation: Institute of Cognitive Science and Technologies (ISTC), Italian National Research Council (CNR), Trento, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Bassetti
authors.affiliation: Department of Computer Science, University of Verona, Verona, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Cristani
mesh_terms: D000465:Algorithms; D006801:Humans; D007398:Interpersonal Relations; D010363:Pattern Recognition, Automated / Q000379:methods*; D010781:Photography; D012919:Social Behavior