1. School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing, China;
2. Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, Nanjing University, Nanjing, China;
3. Collaborative Innovation Center for the South Sea Studies, Nanjing University, Nanjing, China;
4. Collaborative Innovation Center of Novel Software Technology and Industrialization, Nanjing University, Nanjing, China;
5. Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China