1. School of Resources and Environmental Science, Hubei Univ., 368 Youyi Rd., Wuhan 430062, China.
2. School of Architecture and Art Design, Hunan Univ. of Science and Technology, Taoyuan Rd., Xiangtan 411201, China (corresponding author).
3. School of Resource and Environment Science, Wuhan Univ., 129 Luoyu Rd., Wuhan 430079, China.
4. School of Geomatics, East China Univ. of Technology, 418 Guanglan Rd., Nanchang 330013, China.