1. College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China
2. 3D Information Collection and Application Key Lab of Education Ministry, Capital Normal University, Beijing 100048, China
3. Beijing State Key Laboratory Incubation Base of Urban Environmental Processes and Digital Simulation, Capital Normal University, Beijing 100048, China
4. Surveying and Mapping Institute, Lands and Resource Department of Guangdong Province, Guangzhou 510670, China