3D laser scan data could fast-track rebuilding of Notre Dame cathedral
Late Vassar Professor Andrew Tallon (right) took laser scans of Notre Dame from more than 50 sides.
(Web Desk) – As the donations pour in to aid the reconstruction efforts of the fire-damaged Notre Dame cathedral in Paris and the French government opens the question of whether to rebuild the 850-year-old landmark as it was, engineers, architects and contractors can turn to 3D laser scan data of Notre Dame to help with the government’s pledge to reconstruct the building within five years.
“Having laser scans [of Notre Dame] is critical in shortening the reconstruction time frame,” says John Russo, president and CEO of Architectural Resource Consultants and president of the U.S. Institute of Building Documentation.
“If you don’t have that data, where do you go? You are going back to hand drawings that may not exist and those are going to be two-dimensional and not have as much information. As far as answering questions and shortcutting the timeline on doing the repair work, 3D scans are going to shave an incredible amount of time off.”
The late Andrew Tallon, an art history professor at Vassar College in upstate New York, worked with colleagues in 2015 finish a laser scan process at Notre Dame. Using a tripod-mounted Leica ScanStation C10 laser, Tallon spent five days mapping Notre Dame. Combining scans with high-resolution panoramic photos, Tallon added color to his data, giving potential project engineers and contractors an even greater amount of information.
The Notre Dame project from Tallon, which saw him reposition the scanner 50 times, created more than one billion points of data — a high-resolution digital blueprint of Notre Dame.
These records have revolutionized the understanding of how the spectacular building was built - and could provide a template for how Paris could rebuild.
According to Wired, "architects now hope that Tallon’s scans may provide a map for keeping on track whatever rebuilding will have to take place."
In 2015, National Geographic profiled Tallon and his unique scanning process, highlighting his digital imaging of the Notre Dame Cathedral.
For centuries, the only tools we had to measure medieval buildings and structures were primitive - strings and rulers, pencils and plumb bobs - but by turning to 21st-century technology, Tallon was able to tease out the secrets of this miraculous structure.
"If I had texts at every point, I could look in the texts and try to get back into the heads of the builders," Tallon told Nat Geo. "I don’t have it, so it’s detective work for me."
Eventually those millions of dots form a three-dimensional snapshot of the cathedral, and the resulting images are meticulously precise; if the scan is done properly, Tallon told Nat Geo, it should be accurate within 5 millimeters.
According to The New York Times, it took less than an hour for the fire to spread from the attic of the cathedral and engulf the roof, toppling the central spire.
Construction on the cathedral began in the year 1163 and finished in 1345, according to an NYT piece about the history of the cathedral, and the wooden roof contained historic beams from the year 1220, all of which were destroyed by the blaze.
Support for the recovery efforts have begun pouring in, with wealthy Parisians and companies pledging more than US$450 million in donations to Notre Dame’s restoration.
Despite the extensive damage, the NYT reports that most of the priceless artifacts and the stone structure of the cathedral remain intact - though only time will tell how long it’ll take to restore the beloved structure to a semblance of its former glory.
