1. College of Geoscience and Surveying Engineering; China University of Mining and Technology; Beijing China
2. Beijing Key Laboratory of Spatial Information Integration and Its Application; Peking University; Beijing China
3. Department of Civil; Environmental and Geomatic Engineering; University College London; UK
4. Rutherford Appleton Laboratory; Harwell Oxford UK
5. School of Software and Microelectronics; Peking University; Beijing China