A non-contact measurement method for rock mass discontinuity orientations by smartphone

Smartphones are usually packed with a large number of features. An increasing number of researchers are paying attention to the technological capabilities of smartphones, which is a new topic and research interest. This paper proposes a method using smartphones and digital photogrammetry to measure the discontinuity orientation of a rock mass. Smartphone photos satisfying a certain overlap rate provide an efficient method for generating point cloud models of rock outcrops based on image matching. Using the target and the generated point cloud model allows for determining actual geographic coordinates and the measurement of discontinuity orientations. The method proposed has been applied to two different study areas. The discontinuity orientations measured by the proposed method are compared with those measured by the manual method in two cases. The results show a good agreement, verifying the reliability and accuracy of the proposed method. The main contribution of this paper is to use knowledge of coordinate rotation to determine the actual geographic location of the model through a square target. The equipment used in this study is simple, and photogrammetric field surveys are easy to carry out.