[1] Ecole Mines Douai, Dept IA, F-59508 Douai, France
[2] Inria Lille Nord Europe, DOLPHIN Res Team, F-59650 Villeneuve Dascq, France
[3] Univ Lille 1, UMR CNRS 8022, Lab LIFL, F-59655 Villeneuve Dascq, France
[4] Univ Nice Sophia Antipolis, UMR CNRS 6070, Lab I3S, F-06903 Sophia Antipolis, France