Rapid and low cost ground displacement mapping using UAV photogrammetry

Ground displacement mapping has become a crucial issue for landslide hazards assessment. Unmanned Aerial Vehicle (UAV) offers many advantages in mapping applications. The objective of this study is to analyze ground displacement by UAV. This study utilizes UAV DJI 4 Pro for the landslide area in conservational forest Semarang, Indonesia. The study area for mapping is 12 ha, divided into 8 points. Three Control Points 2 × 2 meters were applied. Aerial photographs were taken during the rainy season, August 21st, 2021 and March 30th, 2022. Agisoft software was used to obtain the point cloud and Cloud Compare was used to estimate the landslide surface area. The final results show there are 2 point areas occur ground displacements. In the first location, the landslide surface area is 3420 m2, with the depth of landslide 19 m. The ground displacement occurs in 79.4 m western. The second location landslide surface area is 3576 m2, with the depth of landslide 4 m. The ground displacement occurs in 60.3 m to the west. This study concludes that UAV is applicable in photogrammetry to analyze ground displacement. The procedures in this study can be used for monitoring a landslide area with rapid results and a low-cost budget.