Application of Photogrammetric Computer Vision and Deep Learning in High-Resolution Underwater Mapping: A Case Study of Shallow-Water Coral Reefs

Abstract. Underwater mapping is vital for engineering applications and scientific research in ocean environments, with coral reefs being a primary focus. Unlike more uniform and predictable terrestrial environments, coral reefs present a unique challenge for 3D reconstruction due to their intricate and irregular structures. Traditional 3D reconstruction methods struggle to accurately capture the nuances of coral reefs. This is primarily because coral reefs exhibit a high degree of spatial heterogeneity, featuring diverse shapes, sizes, and textures. Additionally, the dynamic nature of underwater conditions, such as varying light, water clarity, and movement, further complicates the accurate geometrical estimation of these ecosystems. With the rapid advancement of photogrammetric computer vision and deep learning technologies, there are emerging methods that have potential to enhance the quality of its 3D reconstruction. In this context, this study formulates a coral reef reconstruction workflow that incorporates these cutting-edge technologies. This workflow is divided into two core stages: sparse reconstruction and dense reconstruction. We conduct individual summaries of the relevant research efforts in these stages and outline the available methods. To assess the specific capabilities of these methods, we apply them to real-world coral reef images and conduct a comprehensive evaluation. Additionally, we analyze the strengths and weaknesses of different methods and identify areas for improvement. We believe this study offers valuable references for future research in underwater mapping.