João P. Barreto Paulo Peixoto Jorge Batista Helder Araújo Improving 3D Active Visual Tracking. 412-431 http://dx.doi.org/10.1007/3-540-49256-9_25 1999 conf/icvs/1999 ICVS db/conf/icvs/icvs1999.html#BarretoPBA99