Structural health monitoring and inspection of dams based on UAV photogrammetry with image 3D reconstruction

This study presents a three-dimensional (3D) reconstruction model based on unmanned aerial vehicle (UAV) images for dam emergency monitoring and inspection. The structure from motion method is adopted to generate a high-precision 3D dam model with scene geometry by matching the features in multiple overlapping images. Then, the generated model is used to calculate the 3D point coordinates and camera pose through the bundle adjustment system. Effect of ground control points on the model accuracy is analyzed by different position sets for adaptation to various situations. The proposed emergency monitoring model is verified on two rock-fill dams, inspection model is utilized on a concrete dam, and damage detection method is achieved on a small-scale dam model with loadable panels. Results show that the proposed 3D dam reconstruction model based on UAV images can obtain satisfactory accuracy and result in a significant improvement in the dam monitoring and inspection efficiency.