2026 Volume 21 Issue 2 Pages 161-172
Accurate measurement of small-scale slope failures remains challenging without the use of expensive surveying equipment or specialized techniques, particularly when ensuring safety by avoiding direct access to the slope. In this study, we propose a novel method for measuring small-scale slope failures on valley-side slopes from a safe road surface using a smartphone and a long rod for image capture. The applicability and factors contributing to measurement accuracy are examined. Through the generation of a 3D model of a hypothetical slope and subsequent accuracy verification, the following findings are demonstrated: (1) the robustness of the proposed measurement approach, which combines vertically mounted rod photography and handheld photography, and (2) several strategies for improving accuracy, namely installing features such as aerial markers that facilitate error verification and manual correction, installing a standard scale to provide precise length measurements for each coordinate axis, and installing a leveling rod to correct the vertical axis. Applying elements of the latter strategy to the experimental results reduced measurement errors and achieved the target accuracy in 5 out of 8 cases.
