1. Institute of Communications and Computer Systems (ICCS), Greece and School of Rural Surveying and Geoinformatics Engineering, National Technical University of Athens, Greece
2. Department of Applied Mathematics and Theoretical Physics, University of Cambridge, United Kingdom and Institute of Communications and Computer Systems (ICCS), Greece
3. School of Rural Surveying and Geoinformatics Engineering, National Technical University of Athens, Greece
4. Institute of Communications and Computer Systems (ICCS), Greece