Vision-based damage identification for beam-type structures using area scanning without calibration

The conversion of image coordinates to physical coordinates, usually through camera calibration, is necessary to obtain the accurate displacement when using the vision-based measurement system. This paper proposes a vision-based damage identification for beam-type structures using area scanning without calibration. First, the modal parameter identification using the uncalibrated pixel displacement is derived to verify the feasibility of omitting the calibration process. Then, a flexible area damage detection is proposed through area scanning tactic, which focus on the desired detection area without the consideration of the overlapping region measurement and the baseline mode shape data. Finally, an experiment validation involving two scanning strategies is performed to verify and demonstrate the effectiveness and accessibility of the proposed method. The results indicate that the fluctuation of mode shape curvature (MSC) caused by damage needs to be greater than that of MSC itself to make the damage identification successful.