High-speed videogrammetry for structural response of rocky slopes in shaking table tests

Conventional high-speed videogrammetry based on artificial marker points has lower applicability in the application of structural response measurement on rough and non-flat surfaces, such as rocky slopes, etc. In this paper, a high-speed videogrammetric method based on speckle patterns and digital image correlation (DIC) technique is proposed to monitor the deformation of the slope accurately. The method is mainly divided into the following parts: (1) Acquire the time-series displacement of scattering features by a dual matching strategy of stereo matching and sequence matching; (2) Obtain the intrinsic and extrinsic parameters of the camera system and 3D reconstruction of the feature points by using a stereo calibration method based on a planar target. (3) Unify the local coordinate systems of different fields of view by calculating the coordinate transformation parameters from the 3D coordinates of the corresponding points. The validity and reliability of the method are verified in the shaking table tests of the slope structure model, which show that the proposed method achieves sub-millimetre positioning accuracy and vibration frequency measurement deviation better than 1%.