1. Assistant Professor, School of Rural and Surveying Engineering, National Technical Univ. of Athens, Athens 15780, Greece (corresponding author).
2. Ph.D. Candidate, School of Rural and Surveying Engineering, National Technical Univ. of Athens, Athens 15780, Greece.
3. M.S. Student, School of Rural and Surveying Engineering, National Technical Univ. of Athens, Athens 15780, Greece.