Exploring the potential of smartphone photogrammetry for field measurement of joint roughness

Rock joints play a crucial role in determining the behavior and stability of rock masses. Despite their importance, there is a lack of devices for easily and accurately measuring joint roughness in field conditions. This research explores the potential of smartphone photogrammetry as a solution for large-scale joint roughness mapping. A large natural rock joint from an open pit mine in Yunnan, China, served as the specimen. Both two dimensional (2D) and three dimensional (3D) roughness parameters were utilized to characterize joint roughness. The study found that the accuracy of smartphone photogrammetry is acceptable when operated with guidance. The measurement errors were 1.7%, 4.7%, 7.8%, and 6.1% for the Z1, Ai, Z2, and PSD-D roughness parameters, respectively. In conclusion, this study demonstrates that using smartphone photogrammetry as a portable and cost-effective method for measuring joint roughness in field conditions has the potential to significantly benefit engineering geological investigations.