Modern shallow reef orthomosaic dataset from the ABC Islands (Leeward Antilles, Caribbean)

Library of shallow coral reef Structure-from-Motion/Multi-View Stereo orthomosaics from the islands of Aruba, Bonaire, and Curaçao (Netherlands Antilles, southern Caribbean). This dataset was produced in the summer of 2022 and 2023, during the field component of "Frozen in Time", a project within the DFG Priority Programme (SPP2299) "Tropical Climate Variability & Coral Reefs". At modern reef level, transects of 30×5 m were set to run from the reef flat to just past the reef crest, translating to an approximate starting water depth of ~5 m and ending at ~10 m. A transect tape was used to indicate horizontal length, while three 0.4 m long scale bars were placed equidistant along the transect tape. Image acquisition was conducted either by swimming on the surface (Curaçao) or underwater (Aruba and Bonaire) along parallel tracks. Two 27 megapixel GoPro HERO 10 Black Edition cameras (3 mm focal length and resolution of 5568x4176 pixels) were attached to a 1.5 m wooden pole at slightly offset angles. All photos were taken in time lapse mode (1 photo per s), with a wide field of view. Camera settings and image acquisition techniques were adapted from previous studies reproducing 3D structure of coral reefs. For each transect, ~250 photos were collected with a 70-80% forward overlap. The bottom depth of each scale bar was recorded with a dive computer. Once back from the field, we generated 3D-models (digital twins) using Agisoft Metashape Professional (version 2.1.0 build 17532). Each digital twin can be directly imported into GIS and will be automatically scaled if using local coordinates.