1. Faculty of Electronics and Telecommunication, VNU University of Engineering and Technology, Hanoi, Vietnam
2. Department of Electronics, Nam Dinh University of Technology Education, Nam Dinh, Vietnam
3. Department of Geological-Geotechnical Engineering, Hanoi University of Mining and Geology, Hanoi, Vietnam
4. Geographic Information System group, Department of Business and IT, University College of Southeast Norway, N-3800, Bø i Telemark, Norway