Measurement of three-dimensional shrinkage deformations and volumes of stabilised soft clay during drying with Structure from Motion photogrammetry

Abstract The paper applies the Structure from Motion photogrammetry technique to measure three-dimensional shrinkage deformations of a cylindrical specimen during drying. A clay–binder mixture was statically compacted, and its behaviour observed for four weeks with newly established photogrammetric system. complete surface information including XYZ coordinates RGB values then reconstructed formed into dense point cloud data, which volume change are computed. In determination, achieves fine reproduction surface, leading satisfactory accuracy. computed deviation within 495.3 mm 3 (0.24%) 4170 (1.83%) dummy cylinder clay specimen, respectively. Both significantly smaller than deviations classical approach that involves artificially creating markers on surface. computation deformations, proposes novel method detects fast feature histogram clouds matches detected descriptors, an improvement in deformation determination. compacted sample shrinks, axial increase quasi-linearly height. However, due noticeable tilt occurred drying, calculated radial scattered at same height appear misleading. Circumferential strains therefore adopted represent true material behaviour.