Application of Structure from Motion Method to Determine Direction of Slope Failure

Discontinuity planes like bedding, fault, or joint are an essential parameter that can be used to determine the slope stability of an outcrop. In most cases, measuring discontinuity planes could be done using a geological compass. However, measurement using this method need a long time and sometimes could be hazardous on hanging cliff. Visualizing geological outcrop into a 3D model could potentially alleviate this problem. One of the methods to visualize an outcrop into 3D form is Structure from Motion (SfM). By using SfM methodology, an outcrop could be transformed into a 3D model using a standard handheld camera. These output reached by taking several photographs of the outcrop from a different angle, and process it using SfM software (e.g., Meshroom, Agisoft Photoscan) to generate a dense point cloud, which could be analyzed furthermore using CloudCompare to extract discontinuity planes position. On this research, SfM method is used to generate a 3D model from an outcrop in Ngoro-oro Village, Yogyakarta, which later is used to determine the direction of slope failure using kinematic analysis. This location was chosen because Ngoro-oro village has high landslide potential. Based on this research, there is some difference in discontinuity planes position between the 3D model and actual outcrop.