[1] Shandong Univ Sci & Technol, Coll Geomat, Qingdao 266590, Peoples R China
[2] Univ Eastern Finland, Karelian Inst, FI-80101 Joensuu, Finland
[3] Chinese Acad Sci, Aerosp Informat Res Inst, Beijing 100094, Peoples R China
[4] South China Univ Technol, Sch Econ & Commerce, Guangzhou 510006, Peoples R China
[5] Univ Surrey, Sch Hospitality & Tourism Management, Guildford GU2 7XH, Surrey, England
[6] Shandong Univ Sci & Technol, Coll Foreign Languages, Qingdao 266590, Peoples R China