1. Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong, China
2. The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China
3. Department for National Park Monitoring and Animal Management, Nationalpark Bayerischer Wald, Grafenau, Germany
4. Faculty of Environment and Natural Resources, University of Freiburg, Freiburg, Germany
5. Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences, Koppang, Norway