Assessment of Slope Mapping by Using Unmanned Aerial Vehicle (UAV)

Abstract Unmanned aerial vehicles (UAVs) are an emerging technology for 3D Earth modelling and mapping. UAVs collect aerial images that are used to generate orthophotos with the assistance of navigation systems such as the Global Positioning System (GPS) and telemetry monitors at the Ground Control Station (GSC) for monitoring and controlling the UAV in autonomous flight. However, precision is critical in UAV photogrammetry mapping (PMg) to present acceptable precision measurements of the captured images that closely related to Ground Sample Distance (GSD) as most survey works are gradually shifting away from conventional surveying equipment such as total station and theodolite which has good precision measurement. This study focuses on the application of UAVs at close-range topography and mapping of land slope. Flight through the slope will vary in terms of flying altitude, affecting the GSD’s value for each slope height. The accuracy of PMg for land slope is subsequently assessed by evaluating the accuracy of slope mapping, particularly the slope height derived from Digital Elevation Model (DEM), Digital Surface Model (DSM) of orthophotos and Global Navigation Satellite System (GNSS) survey. This is due to the fact that most PMg is done on almost exclusively horizontal areas, and the GSD change value acquired remains the same. The purpose of this study is to analyze the accuracy of PMg of land slope by land slope mapping at 100m flight high above ground level. the RMSE recorded for x and y coordinate were (RMSEx = 0.654198cm) and (RMSEy = 0.668516cm) while for elevation error was (RMSEz = 0.512062cm). This study’s output is to help and assist authorities in construction planning, particularly during the cutting and filling process; to determine the precise amount of earth required for construction; and control the cost of earthwork.