Multiobjective Optimization of Reality Capture Plans for Computer Vision-Driven Construction Monitoring with Camera-Equipped UAVs

The exponential growth in reality capture and Building Information Modeling (BIM)-enabled construction workflows has created a surge in computer vision-driven solutions that automatically model and compare as-built conditions against BIM, offering project teams actionable insight into construction progress and quality. Despite their significant impact, the performance of these methods heavily relies on the accuracy and completeness of the reality capture. In addition, and especially in the case of reality captures conducted with camera-equipped unmanned aerial vehicles (UAVs), operational requirements - including battery capacity and operator's line of sight (LOS) - should be carefully considered for safe flight execution. Accounting for these technical and operational requirements during reality capture planning requires expertise. In addition, it involves a significant amount of manual tweaking that does not scale well to ongoing changes due to progress on construction projects. To address these limitations, this paper presents a novel multiobjective optimization method to improve reality capture plans aiming to maximize (1) visual coverage of the monitored structure, (2) redundant observation of the structure's components in the collected frames, (3) resolution of the structure's elements in the captured data, (4) canonical camera viewpoints to the structure's topology, and (5) stability of three-dimensional (3D) reconstruction algorithms used to process the data altogether, while (6) reducing the data collection duration. The objectives are also set to meet other technical and operational requirements, particularly for camera-equipped UAVs. Furthermore, a client-server system architecture is presented to visualize, simulate, and optimize reality capture missions in a web-based 3D environment using four-dimensional (4D) BIM to indicate the as-planned expected changes. Five conducted experiments using real-world data demonstrated the method's capability to enhance the quality of user-created reality capture plans. The optimization process resulted in a 7.65% improvement in visual coverage, 30.89% enhancement in the structure's resolution, and 8.95% more stable 3D reconstruction while ensuring the flight paths meet operational requirements.