Discussion of "A 3D image-based method to measure soil stiffness in triaxial tests" by Wang et al. 2024 (DOI: /10.1007/s11440-023-01977-3)

Wang et al. (2024) proposed a new method to measure soil stiffness through triaxial tests. This discussion illustrates some limitations of the proposed method and details several modifications on the post-image analysis process to enhance its capability. These modifications include the introduction of true stereophotogrammetry for camera and triaxial cell wall orientation, optical ray tracing technique for optical ray reconstruction, and three-dimensional digital image correlation (3D-DIC) for full-field two-dimensional (2D) point cloud generation. With these modifications, the capability of the new method can be significantly improved from only local strain to full-field deformation measurement at a higher accuracy and resolution.