A comprehensive study on the application of UAV-based oblique photogrammetry and 3D modeling in metro depot engineering

The metro depot, serving as the critical hub and maintenance center of urban rail transit systems. Its extensive scale, structural complexity, and fragmented information flows pose considerable challenges throughout the planning, construction, and operational management phases. This study aims to systematically develop and validate a comprehensive framework for the application of UAV-based oblique photogrammetry and 3D modeling throughout the entire lifecycle of metro depots.. The paper begins with an in-depth analysis of the complete technological pipeline of oblique photogrammetry, integrating both theoretical foundations and engineering practices, encompassing UAV selection criteria, flight planning, aerial triangulation algorithms, through to the generation of photorealistic textured 3D models using MultiView Stereo (MVS) matching and Poisson surface reconstruction. The study systematically demonstrates four key application values of this technology in metro depot environments.. First, during the planning and design phase, it enables rapid and precise topographic modeling and earthwork calculation, increasing efficiency by more than fivefold while maintaining errors within 3%. Second, during the construction phase, dynamic comparison between multi-temporal reality models with 4D BIM schedules facilitates transparent management of progress, quality, and safety. Third, for operational maintenance, it establishes a real-scene 3D-based platform for visual asset management and intelligent inspection. Fourth, it innovatively achieves deep integration of oblique photography models with BIM, GIS, 3D printing, and 720° VR, laying a solid data foundation for constructing the depot's Digital Twin. Validated through several flagship projects, this research conclusively positions UAV oblique photography as an indispensable core engine driving the digital and intelligent transformation of metro depots.