1. 1. College of Geomatics, Xi'an University of Science and Technology, Xi'an 710054, China
2. 2. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
3. 3. Laoshan District Bureau of Agriculture and Rural Affairs of Qingdao City, Qingdao, Shandong 266061 China