Web-Based Georeferenced 3D Inspection and Monitoring of Bridges with Unmanned Aircraft Systems

The presented paper focuses on the interregional usage of unmanned aircraft systems (UAS) for infrastructural inspection as well as structural health monitoring (SHM). These aerial sensor platforms are used for the inspection of bridges that are difficult to access and distinguished by their height, location, or a combination of both. The UAS inspection is performed by visual cameras or thermal imagers for state detection, whereas object contours are scanned by LiDAR to allow precise close-range inspection and trajectory control. There are challenges in maintaining the precise laser distance control at the infrastructure, such as the LiDAR sensor measurement accuracy and infrastructural and environmental conditions. The presented bridge-specific flight pattern navigation is an essential trajectory planning tool for acquiring reproducible inspection data and its quality. Based on the UAS inspection data, ultrahigh resolution reconstructions of every part of an object are built in terms of two-dimensional (2D) projections before being postprocessed in a full three-dimensional (3D) building model. These models are then integrated into a web-based geographic information system platform developed within the project. It provides georeferenced implementation and visualization of the inspection data as well as all data concerning ongoing and scheduled construction planning or any other building documentation.