{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,2]],"date-time":"2026-02-02T13:58:30Z","timestamp":1770040710774,"version":"3.49.0"},"reference-count":23,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2023,7,26]],"date-time":"2023-07-26T00:00:00Z","timestamp":1690329600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"U.S. Geological Survey"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>We investigate the utility of towed underwater camera systems with tightly coupled Global Navigation Satellite System (GNSS) positions to provide reef-scale bathymetric models with millimeter to centimeter resolutions and accuracies with Structure-from-Motion (SfM) photogrammetry. Successful development of these techniques would allow for detailed assessments of benthic conditions, including the accretion and erosion of reefs and adjacent sediment deposits, without the need for ground control points. We use a multi-camera system towed by a small vessel to map over 70,000 m2 of complex shallow (2\u20138 m water depth) bedrock reef, boulder fields, and fine (sand and gravel) sediments of Lake Tahoe, California. We find that multiple synchronized cameras increase overall mapping coverage and allow for wider survey line spacing. The accuracy of the techniques was sub-millimeter for local length measurements less than a meter, and the bathymetric reproducibility was found to scale with the accuracy of GNSS (3\u20135 cm), although this could be improved to sub-centimeter with the inclusion of one or more co-registered, but unsurveyed, control points. For future applications, we provide guidance on conducting field operations, correcting underwater image color, and optimizing the SfM workflows. We conclude that a GNSS-coupled underwater camera array is a promising technique to map shallow reefs at high accuracy and resolution without ground control.<\/jats:p>","DOI":"10.3390\/rs15153727","type":"journal-article","created":{"date-parts":[[2023,7,27]],"date-time":"2023-07-27T02:07:17Z","timestamp":1690423637000},"page":"3727","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Accurate Maps of Reef-Scale Bathymetry with Synchronized Underwater Cameras and GNSS"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7705-1509","authenticated-orcid":false,"given":"Gerald A.","family":"Hatcher","sequence":"first","affiliation":[{"name":"U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA 95060, USA"}]},{"given":"Jonathan A.","family":"Warrick","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA 95060, USA"}]},{"given":"Christine J.","family":"Kranenburg","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL 33701, USA"}]},{"given":"Andrew C.","family":"Ritchie","sequence":"additional","affiliation":[{"name":"U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA 95060, USA"}]}],"member":"1968","published-online":{"date-parts":[[2023,7,26]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1111\/1095-9270.12016","article-title":"Mapping Submerged Archaeological Sites using Stereo-Vision Photogrammetry","volume":"42","author":"Henderson","year":"2013","journal-title":"Int. J. Naut. Archaeol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"e1077","DOI":"10.7717\/peerj.1077","article-title":"Integrating structure-from-motion photogrammetry with geospatial software as a novel technique for quantifying 3D ecological characteristics of coral reefs","volume":"3","author":"Burns","year":"2015","journal-title":"PeerJ"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1016\/j.geomorph.2015.01.030","article-title":"Measuring coral reef terrain roughness using \u2018Structure-from-Motion\u2019 close-range photogrammetry","volume":"242","author":"Leon","year":"2015","journal-title":"Geomorphology"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"889","DOI":"10.1007\/s00338-016-1462-8","article-title":"End of the chain? Rugosity and fine-scale bathymetry from existing underwater digital imagery using structure-from-motion (SfM) technology","volume":"35","author":"Storlazzi","year":"2016","journal-title":"Coral Reefs"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"269","DOI":"10.1007\/s00338-016-1522-0","article-title":"Mapping coral reefs using consumer-grade drones and structure from motion photogrammetry techniques","volume":"36","author":"Casella","year":"2017","journal-title":"Coral Reefs"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"16737","DOI":"10.1038\/s41598-017-16408-z","article-title":"3D photogrammetry quantifies growth and external erosion of individual coral colonies and skeletons","volume":"7","author":"Ferrari","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1770","DOI":"10.1002\/ece3.2701","article-title":"A simple, fast, and repeatable survey method for underwater visual 3D benthic mapping and monitoring","volume":"7","author":"Pizarro","year":"2017","journal-title":"Ecol. Evol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Palma, M., Rivas Casado, M., Pantaleo, U., and Cerrano, C. (2017). High Resolution Orthomosaics of African Coral Reefs: A Tool for Wide-Scale Benthic Monitoring. Remote Sens., 9.","DOI":"10.3390\/rs9070705"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Raoult, V., Reid-Anderson, S., Ferri, A., and Williamson, J.E. (2017). How Reliable Is Structure from Motion (SfM) over Time and between Observers? A Case Study Using Coral Reef Bommies. Remote Sens., 9.","DOI":"10.3390\/rs9070740"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2512","DOI":"10.1038\/s41598-018-37713-1","article-title":"Effects of bleaching-associated mass coral mortality on reef structural complexity across a gradient of local disturbance","volume":"9","author":"Magel","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"111475","DOI":"10.1016\/j.rse.2019.111475","article-title":"Fluid lensing and machine learning for centimeter-resolution airborne assessment of coral reefs in American Samoa","volume":"235","author":"Chirayath","year":"2019","journal-title":"Remote Sens. Environ."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"525","DOI":"10.3389\/fmars.2020.00525","article-title":"Accurate Bathymetric Maps From Underwater Digital Imagery Without Ground Control","volume":"7","author":"Hatcher","year":"2020","journal-title":"Front. Mar. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1002\/aqc.2654","article-title":"Drones that see through waves\u2014Preliminary results from airborne fluid lensing for centimetre-scale aquatic conservation","volume":"26","author":"Chirayath","year":"2016","journal-title":"Aquat. Conserv. Mar. Freshw. Ecosyst."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Raber, G.T., and Schill, S.R. (2019). Reef Rover: A Low-Cost Small Autonomous Unmanned Surface Vehicle (USV) for Mapping and Monitoring Coral Reefs. Drones, 3.","DOI":"10.3390\/drones3020038"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1410","DOI":"10.1111\/2041-210X.13476","article-title":"A protocol for the large-scale analysis of reefs using Structure from Motion photogrammetry","volume":"11","author":"Bayley","year":"2020","journal-title":"Methods Ecol. Evol."},{"key":"ref_16","first-page":"103120","article-title":"A novel Structure from Motion-based approach to underwater pile field documentation","volume":"39","author":"Reich","year":"2021","journal-title":"J. Archaeol. Sci. Rep."},{"key":"ref_17","unstructured":"Dailey, E.T., and Hatcher, G. (2020). Squid5-Software (Version 1.0.0)."},{"key":"ref_18","unstructured":"Hatcher, G.A., Warrick, J.A., Kranenburg, C.J., and Dal Ferro, P. (2021). Overlapping Lakebed Images and Associated GNSS Locations Acquired near Dollar Point, Lake Tahoe, CA, March 2021."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Over, J.R., Ritchie, A.C., Kranenburg, C.J., Brown, J.A., Buscombe, D., Noble, T., Sherwood, C.R., Warrick, J.A., and Wernette, P.A. (2021). Processing Coastal Imagery with Agisoft Metashape Professional Edition, Version 1.6\u2014Structure from Motion Workflow Documentation.","DOI":"10.3133\/ofr20211039"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1109\/TIP.2017.2759252","article-title":"Color Balance and Fusion for Underwater Image Enhancement","volume":"27","author":"Ancuti","year":"2018","journal-title":"IEEE Trans. Image Process."},{"key":"ref_21","unstructured":"Warrick, J.A., Hatcher, G.A., and Kranenburg, C.J. (2021). Point Clouds, Bathymetric Maps, and Orthoimagery Generated from Overlapping Lakebed Images Acquired with the SQUID-5 System near Dollar Point, Lake Tahoe, CA, March 2021."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Hatcher, G.A., Warrick, J.A., and Dartnell, P. (2023). Colored Shaded-Relief Bathymetric Map and Orthomosaic from Structure-from-Motion Quantitative Underwater Imaging Device with Five Cameras of the Lake Tahoe floor, California; Scientific Investigations Map.","DOI":"10.3133\/sim3501"},{"key":"ref_23","unstructured":"(2021, August 04). U.S. Geological Survey National Water Information System: U.S. Geological Survey Web Interface, Available online: https:\/\/nwis.waterdata.usgs.gov\/nwis."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/15\/3727\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T20:19:24Z","timestamp":1760127564000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/15\/15\/3727"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,7,26]]},"references-count":23,"journal-issue":{"issue":"15","published-online":{"date-parts":[[2023,8]]}},"alternative-id":["rs15153727"],"URL":"https:\/\/doi.org\/10.3390\/rs15153727","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,7,26]]}}}