3D Coral Models from Repurposed Historical Image Datasets

Time series structure-from-motion (SFM) three-dimensional (3D) models of underwater reef images were created from repurposed historical image datasets (RHID) collected during regular monitoring in Lian, western Luzon Island, Philippines from 2009 to 2025. The method’s novelty is its successful repurposing of data to create 3D coral models and to extract surface rugosity as a 3D structure component. These datasets were primarily captured using the photo quadrat method with different cameras at variable water conditions and a very limited number of images per data collection, yet structure component indices were validated in situ with an accuracy of 0.97. Results showed a similar trend between the rugosity and coral cover reflecting a high potential for RHID 3D structure components to proxy coral cover as a measure of reef recovery or decline over time.