Abstract: Real 3D models provide a unified digital spatial base for the digital twin. In urban scenes, the parts that are obscured close to the ground as well as in the aerial view are difficult areas for 3D reconstruction. In view of the complex spatial environment of the city and the limited capability of UAV operations, This paper proposes an air-ground integrated real 3D reconstruction method that takes into account ground position and orientation system (POS) information based on the basic theory of tilt photography and air-ground integrated modelling, and is fine-grained modeled of the historical and cultural district of Foshan city based on this method. The experiments show that compared with conventional methods, the modelling of this method has the advantages of good effect and high efficiency, which is important for the production of real 3D products and multi-scale representation of spatial data, and can provide a better representation of geographical scenes for digital twin applications.

Key words: digital twin, ground position and orientation system information, air-ground integration, real 3D reconstruction