Transformer-based deformation measurement of underground structures from a single-camera video

Measuring the deformation of underground structures, such as excavation and tunnels, is crucial for safe construction and operation. However, conventional methods, such as inclinometer probes and total stations, are labour-intensive and time-consuming for engineers. This paper proposes a transformer-based 3D reconstruction method using single-camera video to rapidly measure structural deformations. The proposed method extracts features from video frames to reconstruct point clouds, generating centrelines and Poisson models for deformation analysis. This allows fast and precise deformation measurement at any position, outperforming traditional methods. The proposed method has achieved sub-millimetre accuracy in small-scale inclinometer casings, and a 5 cm accuracy level in a large-scale tunnel, confirming its capability for detecting subtle deformations. Discrepancies in accuracy for larger structures were attributed to limitations in camera resolution, suggesting that employing 100-megapixel cameras could guarantee millimetre-level accuracy. The method's simplicity and adaptability demonstrate its potential as a practical supplement to existing deformation measurement methods.