When the shock of seeing Notre-Dame engulfed in a catastrophic fire on Monday finally wore off, people around the world were quick to wonder how it would be rebuilt. Many pointed to the work of architectural historian Andrew Tallon, who digitally scanned the structure in 2010 to create a detailed documentation of the building that could eventually help reconstruct it.
Tallon was an early adopter of a technology that is increasingly common today. Known loosely as 3D scanning, it uses lasers to analyze the way light bounces off of a space or object (also known as lidar) to create a digital document of its exact measurements. Microsoft’s now-defunct Kinect sensor used it. Archaeologists use it to discover ancient earthworks in Central America, and many robotics and autonomous vehicle companies use it to help vehicles “see.” The tech is everywhere, with dozens of startups using it in wildly different ways, from mapping malls to taking detailed measurements of people’s bodies for clothing.
For the architecture and engineering industry, 3D scanning offers the ability to create a virtual corollary for any building, whether it’s Notre-Dame or an office complex in the suburbs. Kevin Dowling calls it a “digital twin.”
Dowling is the founder of Kaarta, a 3D-scanning startup that is one of many competitors in this increasingly crowded industry. Though his background is in robotics (which is where the technology was developed, to help robots move around), these days two-thirds of Kaarta’s business is in mapping architecture, engineering, and construction. The company pitches its handheld devices as a faster way to 3D scan than a typical tripod-mounted scanner, cutting down the time it takes to make a “digital twin” from days to hours–which could ultimately make the tech more accessible.
Dowling sees 3D scans becoming a commonplace aspect of owning a building–any building. “In the future, it may be irresponsible to not capture these and other structures,” he says. Insurance companies might request a 3D scan of a building to better assess its potential risks; emergency responders could use them, too. “At some point in the not-too-distant future, a fireman showing up at a building is going to say, ‘Where’s the model?'”
If there’s a silver lining of the Notre-Dame fire, it may be the fact that Andrew Tallon had already done the hard work of documenting it digitally, which could eventually help the restoration process. He was ahead of his time, but 3D scanning is becoming an increasingly important part of preserving and repairing other damaged heritage sites, too.
It’s a technology that seems more necessary than ever, as extreme weather, sea level rise, and other climate change-related risks threaten buildings and monuments alike. Still, affordability and accessibility are major hurdles for thousands of other historic structures. A scanner can cost between $35,000 and $50,000 dollars, so they’re still out of reach for most building owners, and especially for cash-strapped nonprofits and preservation groups.
“There are so many other sites that don’t have that level of people and resources to dedicate toward those efforts and they won’t have the budgets to dedicate toward those efforts,” says Kathy Pattison, Kaarta’s chief marketing officer. Pattison recently helped an architect scan a historic lighthouse in Connecticut in roughly an hour, for instance, and Kaarta has created large scans of the Charminar, the 430-year-old mosque in India in roughly five hours.
But ultimately, Kaarta is a tech company, not a service provider. The task of getting 3D-scanning technology into the hands of architects and preservationists will fall to other groups.
One of the most prominent is CyArk, a 16-year-old nonprofit based in Oakland, California.
The group works with governments all over the world, from Easter Island to Afghanistan, to 3D-scan historic structures and create digital documentation. In 2016, CyArk was 3D-scanning temples in Bangkok shortly before an earthquake damaged the structures; they returned the same year to scan the damage and create construction drawings to help preserve the buildings. Recently, Mexico City invited the nonprofit to do a thorough scan of the entire Metropolitan Cathedral, which was damaged during the 2017 earthquakes.
Part of the goal of many of these projects isn’t just to preserve them, but to track changes over time, to “act as a baseline to identify further damage,” explains CEO John Ristevski. Ultimately, they used their 3D model to deliver a set of traditional 2D construction drawings that the city could use for restoration.
Ristevski joined CyArk in the early 2000s, but left to work on the commercial side of 3D scanning, founding a company that 3D mapped cities (it was later acquired by Nokia for use in autonomous vehicles). He returned to work on heritage and preservation at CyArk as CEO a few years ago, citing the rapid development of scanning tech as one major reason.
“The ability to actually help heritage and answer conservation and preservation issues has greatly changed,” he says. Today, CyArk consults with governments all over the world–not just leading 3D-scanning projects, but helping governments themselves adopt the technology. For instance, they’ve visited Easter Island twice, where government authorities have bought 3D-scanning tech and are now implementing a large-scale preservation project of heritage sites, some of which are endangered by climate change. Likewise, Scotland has organized its own project to scan historic sites all over the country. If a catastrophic event akin to the Notre-Dame fire were to happen there, “I can almost guarantee that they would have a very good record, because it’s just a part of their management plan,” Ristevski says.
Part of CyArk’s mission is to disseminate the knowledge and skills to use 3D scanning to document heritage sites, the way Notre-Dame was preserved digitally. “We’re a small team and our goal is not to scan the whole world . . . but what we can do is train others how to do this,” he says. “If the cultural stewards of these places and the countries where they belong can adopt these technologies, they might become a standard part of the process.”
The future reconstruction of Notre-Dame will be worked out over coming decades, not years. In that time, technology like 3D scanning will continue to evolve. Whether or not it’s reconstructed to the exact specifications of its “digital twin,” created nearly a decade ago, Tallon’s 3D models will live on as a digital memory, as Alexis Madrigal recently wrote. And hopefully, they’ll inspire other governments to map their own heritage sites–thousands upon thousands of which may not receive the attention that Notre-Dame does, but are no less deserving of preservation.