NOAA U-Boat Scanning
2G Robotics Dynamic Laser Scanner produces high precision 3D models of the U-576, the German submarine that sunk during The Battle of the Atlantic
In 2014, The Battle for the Atlantic, a previously unknown WWII battlefield was discovered off the coast of North Carolina. However, at a depth of 700 feet, the site was too deep for divers to explore. NOAA turned to a trusted collaborator, 2G Robotics, for an effective way to understand the newly identified battlefield. NOAA and 2G Robotics previously collaborated in early 2014 and again in spring of 2016 to document shipwrecks in the Thunder Bay National Marine Sanctuary.
For this new project, 2G Robotics provided its most-advanced, longest range underwater laser scanner, the ULS-500 PRO, to dynamically capture true-scale 3D models of the site. Dynamic underwater laser scanning has quickly become the future of marine archaeology and research. 2G Robotics’ underwater laser scanners have been used on all seven continents for a range of underwater inspections including the high profile Costa Concordia salvage operation and HMS Erebus exploration.
“Dynamic Underwater Laser Scanning is quickly becoming the new standard for underwater archaeology and marine research.”
The ULS-500 PRO was mounted to a Triton 1000/2 free-moving, battery-powered submarine along with Sonardyne’s acoustically aided inertial navigation system (AAINS), SPRINT, for positioning. The ULS-500 PRO was mounted perpendicular to the seabed, facing downwards in order to capture the port side, bow, and stern of the U-Boat in a single pass over a 65m baseline.
In adverse conditions, the Triton 1000/2 operated at a speed of 0.5 knots, which allowed for a single pass to be completed in 7 minutes. A complete 3D model of U-576 was able to be constructed from only 4 passes, however, multiple redundant runs were performed to ensure further accuracy. NOAA was able to achieve a total of two dives on the site. Each dive was composed of 8 passes at an altitude of approximately 7m.
The raw laser point cloud data and navigational data were recorded and processed through EIVA navigational software providing real-time display of data. The point clouds were filtered by intensity and as a result of being geo-referenced, a 3D model was developed without the use of stitching.
Sixteen runs over a 65m baseline were performed at 7 minutes per run. The results of the project highlighted the following key benefits of Dynamic Laser Scanning for shipwreck scanning applications:
Detailed In-Situ Survey
High resolution 3D models reveal fine-scale dimensional features not captured by other methods.
3D models document the present day condition of the site without the need for physical interaction
Reduced Survey Time
Significant reduction in the time to gather data when compared to other techniques.
Dynamic nature of the deployment allows for adjustment of survey methodology to deliver results despite unexpected adverse conditions.
The comprehensive 3D model enables virtual interaction with the site for use in research, educational outreach, and public programming.