1. University of L'Aquila,A2VI-Lab,Department of DISIM,L'Aquila,Italy
2. University of L'Aquila,Department of DISIM,L'Aquila,Italy
3. University of L'Aquila,A2VI-Lab,Department of MeSVA,L'Aquila,Italy
4. University of Salerno,Department of Computer Science,Fisciano,Italy