Sea Technology

SEP 2012

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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mission segment. The ability to swap batteries allowed surface turnaround times of three to four hours between segments. SonarWiz 5 software, made by Chesapeake Technology Inc. (Mountain View, California), was used to review the data, process it into a mosaic, run quality control on the AUV navigation tracks, conduct target analysis and re- ports, and import the digital camera im- ages to get a first blush of photo qual- ity from a dive. SonarWiz enabled the import of 24 hours of sonar data in ap- proximately 30 minutes, speeding up data review and analysis. The software was able to handle all the data collected over the span of the search (more than a terabyte) and to mosaic 1,800 square miles of seafloor in a single project. Digital Camera Photomosaics The WHOI's black-and-white cam- era had a resolution of 1,360 by 1,024 pixels, with illumination supplied by an LED array strobe. A typical photo mis- sion generated 20 gigabytes of data, containing more than 8,000 georefer- enced digital images. The process of producing a final photomosaic involved several steps. It became apparent that trying to import more than 8,000 images into any map- ping program was problematic, with most programs crashing. A manual method was used to distill the images containing target features. Once this process was completed, the selected images were imported into SonarWiz 5 to get an idea of the quality and navigation preci- sion for the mosaic. Creating a photomo- saic by straight mapping of the georeferenced picture tiles resulted in a visually distorted prod- uct. However, this step was useful as a guide for using a feature-matching method with consumer panoramic software, such as Photoshop. The end product was a large-scale, high-resolution composite photomo- saic that allowed detailed analysis to determine the type and age of the ship- wreck located. The shipwrecks that were found dated back as early as the 1600s. (Top) A 250-meter-diameter crater discovered at 1,100 meters depth. (Bottom) "The eye of Saturn" geologic structure discovery. Conclusions This project showed the economic, strategic and data-quality advantages of using an AUV instead of a tradition- al towed system for deepwater search. The Bluefin AUV performed reliably, the EdgeTech sonar produced consis- tently high-quality data and the WHOI camera system proved reliable, with only one incident of software failure. The mission's objective was to lo- cate shipwrecks, but in the process of mapping a large seafloor area, several unusual geological features were dis- covered. The first was a massive hole in the seafloor measuring 250 meters in diameter and showing evidence of some type of flow (gas or fluid), as shown by the sediment trail that led down current. The second feature measured 600 meters in diameter and was nicknamed "the eye of Saturn" because of its unusual shape. Further study of these features could be of in- terest to geologists. References For a list of references, contact Gar- ry Kozak at 2kozak@comcast.net. n Garry Kozak of GK Consulting special- izes in shipwreck lo- cation and has been involved in undersea search for the past 40 years. He is a rec- ognized expert in un- dersea search operations, providing global consulting and training expertise to navies and companies with a critical underwater search need. He now works with EdgeTech. 12 st / SEPTEMBER 2012 www.sea-technology.com

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