An optimized volume determination method based on aerial photogrammetry approach for sustainable environment

Abstract

Beach erosion occurs continuously along the shoreline due to the interaction of natural processes. The beach volume aspect is critical to represent the entire profile of beach evolution. Most advanced survey techniques are costly, requiring arduous control survey setup effort to measure the beach volume. Unmanned Aerial Vehicle (UAV) systems have recently attracted interest in the mapping community, which provides similar products to aircraft systems and comes with Structure from Motion Multi View Stereo (SfM-MVS) technology at a lower cost. The UAV photogrammetric beach volume mappings were mostly conducted by using nonoptimal methods such as low altitude mapping, bundle amount of Ground Control Points (GCPs) distribution, and uncalibrated Ground Sample Distance (GSD). Hence, this study aims to invent an optimized volume determination method accurately using Unmanned Aerial Vehicle (UAV) photogrammetry mapping to minimize work time and perform less laborious beach mapping work for sustainable environment study through several objevtives, firstly, to investigate the camera calibrations, UAV altitudes, and GCPs distribution for optimized beach volume UAV mapping method, secondly, to modify the SfM-MVS photogrammetric volume formula for the development of accurate and optimized beach volume mapping method, and thirdly, to analyze the optimized beach volume mapping method produced. The study was conducted at Desaru Beach, Universiti Teknologi Malaysia (UTM), Irama Beach 1, and Irama Beach 2. Various GCP distributions (3, 4, 5, 6, 8, 10, 15, and 20 GCPs) and UAV mapping altitude differences at 10m, 20m, 30m, 40m, 50m, 60m, 80m, and 100m were studied. This study utilized robust statistical analysis to investigate the beach volume measurement trend and UAV mapping behaviour from various GCP distributions and different UAV altitude mapping. The study results indicated that 4GCP and 100m altitude UAV mapping were the optimal methods for measuring beach volume using UAV with minimal mapping work. Based on the modified photogrammetric volume calculation methods in determining the beach volume, it is evident that the beach volume value is significant. In conclusion, this study shows that the modified photogrammetric volume formula provides better accuracy than the existing volume formula.