3D structural deformation monitoring of the archaeological wooden shipwreck stern investigated by optical measuring techniques

Stereo digital image correlation (stereo-DIC) technique has received special attention in detection and monitoring for quantifying and monitoring the displacement alterations on the surfaces of historical buildings. However, in the field of structural health monitoring of cultural relic, the method of prefabricating speckle patterns on the monitored object is inappropriate. And the method proposed in several literature sacrifices the scale information or the calibration board is used multiple times. This paper provides a practical and effective deformation monitoring system based on stereo DIC for 3D deformation evaluation of the stern of archaeological wooden shipwreck. To calibrate the stereo camera for archaeological wooden object measurement, a self-calibration is proposed to calibrate extrinsic parameters of fixed cameras using the objects surface shape and texture without using a calibration board and sacrificing scale information. In particular, the deformation monitoring data can be used to compensate for the differences in material properties between mo and archaeological wood. The experiment demonstrated that the proposed deformation monitoring system and self-calibration methods are feasible and accurate. Based on this, the measures displacement fields of the archaeological wooden shipwreck stern are presented, and the material properties of the finite element analysis of the shipwreck during the design of the supporting structure were corrected by the deformation monitoring data. The results show that the proposed method has the advantages of good flexibility, strong applicability, and high precision on 3D structural deformation monitoring and structural design of archaeological wooden relics.