Information Engineering Department, University of Padova, 35131 Padova, Italy. dicamill@dei.unipd.it|Information Engineering Department, University of Padova, 35131 Padova, Italy. dicamill@dei.unipd.it|Information Engineering Department, University of Padova, 35131 Padova, Italy. dicamill@dei.unipd.it|Information Engineering Department, University of Padova, 35131 Padova, Italy. dicamill@dei.unipd.it|Information Engineering Department, University of Padova, 35131 Padova, Italy. dicamill@dei.unipd.it