Dr. Nathan Richards and John McCord, researchers at the UNC-Coastal Studies Institute in Wanchese, are experimenting with photogrammetry to create three-dimensional models of shipwrecks along the North Carolina coast. Recently they modeled a beached shipwreck known as the O’Keefe shipwreck in Corolla.
Photogrammetry itself is not a new technique. For decades, researchers have used it to capture landscapes from aircraft photographs to create measurable maps and three-dimensional models. Likewise, innovations in software have allowed archaeologists worldwide to record shipwrecks. McCord and Richards are among the first individuals to use the software for the N.C. coast.
The process has particular applications for beached shipwreck remains along the dynamic N.C. coast. “Part of what we’re looking to do is come up with a method that lets us get to the shipwreck very fast, soon after they’re uncovered, or they’re discovered, with minimal equipment and to capture the best, most accurate data from them in a very short period of time,” said Richards. Using photogrammetry will also allow researchers and resource managers to come back to the sites regularly to determine the degree to which the wreck is being buried, uncovered, falling apart or affected by humans.
The process involves taking a series of photographs to build a model. At the O’Keefe site, McCord and Richards placed coded targets around the sites that each had a unique signature so they could be distinguished when merging the pictures together. The goal of the recording process is to capture every detail of the shipwreck by taking pictures of the targets at multiple angles.
In this case, two sets of photographs, one set from a ground-based photographer and another using an unmanned aerial vehicle, were used to get views underneath and directly over the structure. GPS devices are installed into both cameras so that measurements can be made on the actual size of the wreck from the latitude and longitude coordinates. At this particular site, McCord and Richards took over 300 pictures of the wreckage. Software is then able to reconstruct the location of the photographs, and reconstruct the structure by matching common points. The result is an accurate, scaled representation of the shipwreck. McCord has also completed this process at an underwater site, the remains of the German U-boat U-85 off the N.C. coast.
The North Carolina Underwater Archeology Branch manages hundreds of shipwrecks off the coast. All shipwrecks within three miles of the coastline are protected as property of North Carolina. However, being able to document and manage all of these sites is often difficult due to the costs associated with traveling and the time associated with detailed archaeological recording.
Traditional shipwreck documentation methods often entail measuring every aspect of the structure and then drawing it to scale. Such a method takes hours or days to complete. In the case of beach shipwrecks, recording activities are often at the mercy of small recording windows due to incoming tides or weather changes. “We’re trying to find a better method than investing so much time and money and logistics in doing it the traditional way,” said Richards. Photogrammetric methods can allow researchers in many cases to complete the process in mere minutes, with fully rendered three-dimensional models completed some hours later. This would, hopefully, lead to easier shipwreck documentation.
After the experimental modeling of both the above water and underwater shipwrecks, McCord and Richards hope to be able to create a method that will allow them to model shipwrecks anywhere they find themselves along the N.C. coast. Such an accomplishment will allow them to provide information to management organizations, who may then use the results to make decisions regarding their management and preservation. Critically, the models may also be uploaded to the internet, allowing the public to see these important reminders of U.S. maritime history.