COMPARISON OF UAV LIDAR AND IMAGERY FOR BEACH MONITORING
With recent advancements in UAV based technology the use of airborne photogrammetry and LiDAR poses a new and effective approach for continuous, fast and efficient beach monitoring surveys. This paper aims to compare three platforms (a DJI Phantom Pro 4 using Ground Control Points, a DJI Matrice 200 with built in PPK allowing direct georeferencing and a DJI Matrice 600 with a Riegl Mini-VUX LiDAR system) in order to assess if they enable beach surveys to be performed efficiently, accurately and cost- effectively. A series of beach surveys were performed over a period of 6 months enabling the ability of each UAV surveying technique to be assessed for the identification and evaluation of trends in the changing topography of beaches and shorelines. The study area (Warnbro Sound, Western Australia) is an area that has experienced significant coastal change over the last 20 years as well as several serious weather events in the course of this research. The results show a significant positive bias of a consistent vertical offset to the ground surface by 4–9 cm between the two image based systems in comparison to the LiDAR system. Although these height offsets are significant it is still within the accuracy required to perform successful beach surveys, and all systems were able to quantify the change of the beach shoreline in area (m2) and volume (m3).