PSI - Issue 84

Francesco Allegrezza et al. / Procedia Structural Integrity 84 (2026) 81–88

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Fig. 6. Comparison between reference measure (black) and the vision-based algorithms (red and green).

4. Conclusions This work presents an approach based on template matching techniques for measuring subpixel displacements, using correlation-based similarity measures, appropriately combined with dedicated subpixel estimation strategies. The performance of the algorithms was evaluated through synthetic tests, laboratory tests with controlled displacements, and a field application on a highway bridge, highlighting their accuracy and reliability in operational conditions. The results indicate that the systematic error observed under ideal settings tends to reduce in real acquisitions, confirming the robustness of the proposed approach within practical scenarios. Overall, the proposed methodology proves effective for non-contact monitoring of structural displacements, able to track multiple targets with a single video camera. Chen, H. P., 2018. Structural health monitoring of large civil engineering structures. Wiley Blackwell. Conte, J. P., He, X., Moaveni, B., Masri, S. F., Caffrey, J. P., Wahbeh, M., Tasbihgoo, F., Wang, D. H., Elgamal, A., 2008. Dynamic testing of Alfred Zampa Memorial Bridge. Journal of Structural Engineering 134 (6) 1006–1015. Dong, C.Z., Catbas, F. N., 2021. A review of computer vision–based structural health monitoring at local and global levels. Structural Health Monitoring 20 (2): 692–743. Farrar, C. R., and K. Worden., 2013. Structural health monitoring: A machine learning perspective. Wiley. Feng, D., Feng, M. Q., 2018. Computer vision for SHM of civil infrastructure: From dynamic response measurement to damage detection - A review. Engineering Structures 156 (1): 105–117. Gioiella, L., Micozzi, M., McBain, M., Morici, M., Zona, A., Dall'Asta, A., Simpson, B., Barbosa, A. 2025. Vision-based monitoring of absolute and relative displacements in multi-story buildings during full-scale shake-table tests., Structural Control and Health Monitoring 2618220. Guizar-Sicairos, M., Thurman, S.T., Fienup, J.R., 2008. Efficient subpixel image registration algorithms. Optics Letters 33, 156–158. Meoni, A., Ierimonti, L., Farneti, E., Castellani, M., Filippucci, F., Natali, A., Celati, S., Scozzese, F., Morici, M., Cavalagli, N., Venanzi, I., Agrawal, A.K., Dall'Asta, A., Salvatore, W., Ubertini, F., 2024. A New Methodology for the Diagnosis and Monitoring of Bridges Under Slow Deformation Phenomena. International Journal of Bridge Engineering, Management and Research 1(1), 21424004–1:13. Micozzi, F., Morici, M., Zona, A., Dall'Asta, A., 2023. Vision-Based Structural Monitoring: Application to a Medium-Span Post-Tensioned Concrete Bridge under Vehicular Traffic. Infrastructures 8, 152. References