1. Department of Civil and Environmental Engineering, University of Florence, Via di Santa Marta, 3, 50121 Florence, Italy
2. La Sapienza University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy
3. Interdepartmental Research Center of Geomatics (CIRGEO), TESAF Department, University of Padua, 35020 Padua, Italy