Research purposes:The terrain and geological conditions of the area along the Sichuan-Tibet Railway are extremely complex, with high altitudes, large elevation differences, high mountains and deep valleys in the survey area, and turbulent rivers, which are often inaccessible. The environmental conditions are extremely difficult and dangerous, and it is extremely difficult to carry out contact measurement, or even difficult to complete. In this case, it is necessary to adopt the new technology of air-space-ground integrated surveying and mapping, and comprehensively utilize satellite remote sensing, IMU/DGNSS digital aerial photogrammetry, low-altitude drone photogrammetry, airborne LiDAR measurement, oblique photography 3D modeling, and ground 3D Laser scanning measurement, the establishment of Beidou satellite continuous operation reference station, multi-source data fusion and establishment of three-dimensional geographic information database technologies, give full play to the advantages of various technical means to carry out efficient and safe measurement work.
Research conclusions:(1) Through the research of high-resolution satellite image wide-area mapping technology, the satellite image control point layout plan is determined, and the large area 1 ∶10 000 topographic map and digital orthophoto map production under the condition of a small number of control points are realized. (2) Research on digital aerial imagery to accurately solve IMU/DGNSS and zone layout technology, realize the appropriate number of image control points combined with POS data block adjustment, and complete the 1 ∶2 000 mapping work for the entire Sichuan-Tibet railway. (3) In key projects area, airborne LiDAR, ground 3D laser scanning technology research is carried out, the use of aerial survey methods to collect 1 ∶500 topographic maps of work sites and 1 ∶200 cross-sectional maps is realized based on 3D large scenes. (4) The research on the establishment of continuous operation reference stations based on Beidou Technology, and the construction of a high-precision Beidou satellite navigation and positioning reference station network can provide accurate high-temporal-resolution displacement field and velocity field information for the Sichuan-Tibet Railway to form a high-resolution dynamic time-space reference. (5) Research on 3D modeling of oblique photography real scenes, multi-source data fusion and 3D geographic information database technology, establish 3D route selection virtual survey platform, 3D geological interpretation platform, and pave the way for railway intelligent design and BIM forward design. (6) The research results can be applied to the survey and design of railways in complex and difficult mountainous areas such as the Sichuan-Tibet Railway.