UAV photogrammetry and 3D reconstruction: application in coastal monitoring

Recent advancements in remote sensing platforms have resulted in the development of small unmanned aerial systems (UAVs), commonly referred to as drones. UAVs have emerged as alternatives that are more flexible in aerial photography due to the relatively low cost of operation, support for missions that are more frequent, appreciable areal coverage, improved ground resolution, and ease of use. UAVs have the additional capability of performing missions and acquiring data autonomously and are capable of collecting data in inaccessible areas, including coastal environments. Furthermore, UAVs are capable of generating orthophotos and digital elevation models with resolutions higher than 10 cm. These high resolution products facilitate the quantification of morpho-sedimentary changes, including nearshore and longshore sediment transport, among others. They are used in the mapping and monitoring of wetlands, coral reefs, shorelines, beach topography, and bar dynamics. This chapter discusses the use of UAVs in photogrammetry and 3D reconstruction, with a focus on application in coastal environments. A case study is presented which shows a current application in Ghana for monitoring beach sediment volume dynamics. The results indicate 34% imbalance in sediment along the beach with highest sediment removal occurring around August, which coincides with the season of high wave energy along this coast.