UAV-BASED OBLIQUE PHOTOGRAMMETRY FOR 3D RECONSTRUCTION OF TRANSMISSION LINE: PRACTICES AND APPLICATIONS
Regular inspection of transmission line is an essential work to ensure reliable supply and distribution of electric power. Considering that the conventional time consuming and economic inefficient methods can not satisfy new coming demands, an inspection strategy is proposed in this study, which aims to achieve off-site visual inspection instead of in-site inspection. The most challenging task is 3D model reconstruction of transmission line. Therefore, based on oblique imaging technique and the flexibility of UAV platforms, an UAV-Based oblique photogrammetric system is designed and manufactured for data acquisition of transmission line. The system integrates a dual-camera imaging system, an onboard GNSS (Global Navigation Satellite System) receiver and a ground fixed GNSS station. Beside, using open-source and commercial software packages, a data processing pipeline is also proposed for 3D model reconstruction. The experimental results demonstrate that the UAV-based oblique imaging system could obtain images of power pylons in four different directions and provides enough information for the successful model reconstruction. Without GCPs, the dual-strip flight mode is recommended for flight configuration to achieve high geo-referencing accuracy. Compared with the traditional methods, the proposed solution can achieve off-site inspection of transmission line.