Historians Turn To 3D Imaging To Preserve Sites Threatened By Climate Change
In coastal cities like St. Augustine, historic sites are facing modern threats - climate change and sea level rise. Now historians and preservationists are turning to technologies like 3D imaging as they look to protect those cultural resources for future generations.
Around 1,000 people were buried in Tolomato Cemetery in the 17th and 18th centuries, including Elizabeth Forrester, whose grave is thought to be the oldest marked burial in Florida.
The site, formerly a Franciscan Native American mission, is located at a low point in the city.
When Hurricane Matthew skirted the east coast in 2016, the flood waters were about two feet deep in the cemetery. The ground collapsed in several areas, vaults were damaged by water and falling trees and the Tolomato Cemetery Preservation Association, the organization that handles things like restoration and preservation, lost a lot of records that were being stored on site.
Scientists say climate change is making intense storms like Hurricanes Matthew and Irma stronger and more frequent. On top of that, sea level rise is exacerbating flooding.
Elizabeth Gessner, who is the President of the Tolomato Cemetery Preservation Association, said storms like Matthew are expensive and difficult to recover from, but they’re manageable. She’s more concerned with what might happen to the cemetery further down the road.
“If you go to the Aegean, the reason there's underwater archeology is not because they had Matthew and Irma, but because in some places the sea line changed and there are whole cities under there,” she said. “This is not going to be under water at any point in the near future, but things just do not last forever.”
That’s why her organization is turning to Davide Tanasi from the University of South Florida and La Florida, a free and open access website with the goal of creating a collective biographical database of all the people who lived in Florida during the colonial period.
“We are using two different kinds of 3D digital imaging technologies, such as 3D scanning and digital photogrammetry, to map out, in three dimensions, the entire cemetery and all the markers and the funerary monuments in it,” said Tanasi, who is an Assistant Professor of Digital Humanities and the Director of the Institute for Digital Exploration, which conducts visualization projects of cultural heritage sites in Florida and the Mediterranean.
Put simply, he’s using devices that project laser beams to record information about the physical location of points in space. That data is then used to produce a digital version of a physical object.
The technology was developed about 15 years ago for military purposes. In the past ten years or so it’s become very common when it comes to the preservation and documentation of cultural resources.
While those 3D scanners are running, Tanasi also takes digital photographs of every single monument. “So what we do is basically go around these monuments, taking hundreds and hundreds of pictures, and then a specific processing software will align and merge all those pictures into a 3D model,” he explained.
That process is known as photogrammetry.
“So the process of wrapping up the data and producing the 3D model, this is very lengthy, very time consuming. It’s much faster to capture the data on site,” he said. “I expect that in a couple of months we will have the all the 3D models ready. Keep in your mind there are 105 funerary monuments here, so we have to process and finalize 105 individual 3D models plus the overall 3D model of the cemetery.”
Several interns and graduate students will help him with that process back in Tampa.
Once the 3D modeling is finished, Tanasi said they’ll be able to monitor the condition of the cemetery going forward. “We can compare basically, in a few years, re-scanning the site, what has happened to the cemetery in two, three, x years, comparing the 3D models,” he said. “Also, the 3D model can be used to design restoration plans.”
And they plan to develop a 3D tour. “We know that these kinds of experiences trigger the interest of the public to come and see the real place,” he said. “So this is going to, down the road, bring more people to Tolomato Cemetery.”
He said this process will also reveal what some of the cemetery’s more eroded gravestone and marker inscriptions say.
“Many of the markers here have very fading inscriptions, they're not readable anymore,” he said. “But we can use algorithms to improve the readability of those inscriptions and make them readable again, and provide new data to historians and the historians working with the La Florida project to know more about these individuals buried in the cemetery.”
A similar project has been underway at the Castillo de San Marcos for the past few years.
“A lot of the history of the people that came through the Castillo, and later on known as Fort Marion, is etched upon the walls,” said Steve Roberts, Chief of Interpretation and Education for Castillo de San Marcos and Fort Matanzas National Monuments. “Whether they were bored Spanish soldiers that carved ships on the walls or imprisoned Native Americans that while in prison here drew pictures on the wall, carved into the plaster of the walls. Obviously that's something that is very important, because it really tells the story that this isn't just an old building, but this was a building that people were in, that tells a people’s story.”
“Those imprisonment stories are very important to the Native American people that still see this as an important part of their own traditions. One of our big issues is as that plaster wears away, as the building erodes away, is how do we protect those? And one of the ways that we're doing that is we're really focusing on technology,” he went on to say. “We are currently working on a project with the University of South Florida to do a complete 3D imaging of the Castillo, both inside and out, so that that data, so that information, so that artwork will be protected forever.”
The Digital Heritage and Humanities Center has been doing this kind of cultural heritage work for nearly two decades, primarily working at sites that are threatened or imperiled for some reason, and often working with agencies or government partners that are trying to formulate long term strategies related to preservation and conservation. They frequently work with the National Park Service and are also collaborating with La Florida on other projects.
She spoke with Ira Flatow in a November episode of Science Friday recorded live in Tampa about some of her other projects, like mapping a prehistoric cat sculpture made by the Calusa people, sinkholes in Florida and a former NASA launch pad.
“We’re interested in climate change and [the] sort of preservation strategies that will have applications not only for the National Park Service sites, but more broadly for the city as well,” she said. “At the Castillo de San Marcos we’re very concerned with storm surge impact and things that have sort of intensified as a result of climatic change and alterations in weather patterns.”
Much like what’s being done at Tolomato Cemetery, once the Castillo project is finished the NPS will be able to monitor changes at the site over time. Collins and her team will also be putting together a 3D tour of the 17th century Spanish fort. In fact, using their scanning results, some wayside signs have already been erected around the perimeter of the Castillo that have 3D tactile elements.
But the process of gathering images and data at a site like the Castillo is extremely time intensive. For the Castillo alone, which they’re still working on, there are more than 1,000 position points that have been documented. And in addition to the high resolution 3D images and GPS data being gathered, they’re using geophysics to survey the base of the structure and what’s underground.
“We've pretty much gotten to the final phases of our field work efforts, which will probably wrap up by September of this year.... And then we'll be doing more with data processing,” Collins said. “So I would assume that over the next year, year and a half, all of these things are going to be really readily available and able to be shared and incorporated into learning and education more broadly.”
“In the last two years, this has become certainly a standard plan for the preservation of cultural heritage, which is in danger not just by natural catastrophes, but by catastrophes in general,” Tanasi said of the 3D imaging process. He pointed to the recent fire at the Cathedral of Notre Dame in Paris.
“The French government is now using a 3D model of the cathedral, which was carried out four years ago, as a starting point for the reconstruction of the cathedral,” he said. “So, just in case, you never know, if something happens to the Tolomato Cemetery, we have an immortal 3D model of it and, eventually, with 3D printing technology, we can 3D print it out.”