The Cathedral Notre-dame de Paris and the river Seine

3D laser scans could be key in rebuilding Notre Dame

Image credit: Infomods |

In the wake of a devastating fire that tore through the iconic Notre Dame in Paris on 15 April, digital 3D scans of the cathedral captured by a late architect and art historian could be crucial in restoring the signature landmark.

In 2015, late architect and Vassar College professor Andrew Tallon – who died in November 2018 of brain cancer at the age of 49 – attentively captured every precise detail of Notre Dame cathedral by using a mix of laser technology and digital photography.

Using more than one billion points of data, Tallon was able to bring the cathedral to life in what is considered to be the most accurate rendering of the building ever made.

“Can it help us rebuild? Yes, it can,” said Columbia art history professor Stephen Murray. “I think it’s terribly important.”

Tallon meticulously mapped the gothic cathedral using a rotating laser scanner, which scanned the surrounding 3D area by sending out laser beam sweeps, to measure exact 3D specifications of the interior and exterior of the church throughout more than 50 locations.

Tallon's work that separate it from other digital scans of Notre Dame's ilk, is that it created not only a copy of how the building looked in the present moment, but also how it changed over time. The painstaking reconstruction, shown, uses more than 1 billion data points

Tallon's work that separates it from other digital scans of Notre Dame's ilk, is that it created not only a copy of how the building looked in the present moment, but also how it changed over time.

Image credit: Andrew Tallon/Vasaar College

Made by Leica Geosystems, the device then measured the distance between every point the laser hits and the device itself, allowing for the reconstruction of Notre Dame with an accuracy of 5mm.

Tallon used panoramic photographs of the same locations mapped by lasers to overlay aesthetic detail, which allowed him to stitch together a replica that was not only accurate in dimension but in physical appearance.

Combining laser scans with the spherical panorama pictures captured, “it would look more like the skin of a building we’re accustomed to seeing”, said Vassar College professor Lindsay Cook, who was a colleague of Tallon’s.

Cook added that Tallon created images that “his students would understand and would want to see, and that would really dazzle the eye.

“Those images are almost uncanny, they’re sort of other-worldly,” Cook said. “That's largely because they come from this laser scan. Underneath all the armature is the robust cloud-point data [Tallon] had amassed through the laser scan.”


Tallon used more than one billion data points to create the 3D rendering of the iconic building

Tallon was still at work on a project related to Gothic structures when he passed away in November. Now his colleagues at Vassar College in New York, with the help of his wife, are wading through his research to see what can be done with his raw data.

“As you can imagine, the data is ample,” Cook said. “There are certain images that have been created, but there are all kinds of other ways you can put it together and create new renderings. The raw material is there for future renderings.”

However, Cook said it’s unclear whether French authorities involved in overseeing Notre Dame’s restoration will want to use Tallon’s data.

“Of course, it’d be available to them if they decide that's necessary,” she said. “It’s really wonderful the material exists so there’s at least a backup of all of this data.”

In addition to Tallon’s 3D laser scans of the Notre Dame, video-game artist Caroline Miousse told The Verge that she had dedicated two years to modelling the cathedral down to each individual brick while working on Ubisoft’s ‘Assassin’s Creed: Unity’ – designs which could also provide useful for the restoration of the Parisian landmark.

French President Emmanuel Macron vowed to rebuild the iconic landmark, even as some 400 firefighters were still battling the massive blaze on the evening of 15 April.

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