3D mapping of Notre Dame will help restoration

April 15, 2019 - By Tracy Cozzens

Detailed 3D maps of the iconic and historic Notre Dame Cathedral in Paris hold out hope for accurate reconstruction after it was devastated by a massive fire April 15. Both the ceiling and the spire were destroyed, as well as internal woodwork.

But the information to restore the cathedral is abundant. Besides photos, in 2015 art historian Andrew Tallon used laser scanners to create an immaculately accurate model of the cathedral, as reported in this National Geographic feature.

Laser scans, with their exquisite precision, don’t miss a thing. Mounted on a tripod, the laser beam sweeps around the choir of a cathedral, for example, and measures the distance between the scanner and every point it hits. Each measurement is represented by a colored dot, which cumulatively create a three-dimensional image of the cathedral. “If you’ve done your job properly,” says Tallon, the scan is “accurate to within five millimeters [.5 centimeter].”…

Tallon figured out how to knit the laser scans together to make them manageable and beautiful. Each time he makes a scan, he also takes a spherical panoramic photograph from the same spot that captures the same three-dimensional space. He maps that photograph onto the laser-generated dots of the scan; each dot becomes the color of the pixel in that location in the photograph.

As a result, the stunningly realistic panoramic photographs are amazingly accurate. At Notre Dame, he took scans from more than 50 locations in and around the cathedral—collecting more than one billion points of data.

Assassin’s Creed Unity. Another source comes from a video game company. Immaculate models of the cathedral were collected for the creation of the best-selling “Assassin’s Creed: Unity,” where the hero/player is able to climb both the outside and inside of the massive edifice.

An artist for the Ubisoft game, Caroline Miousse, told The Verge:

In the case of the Notre Dame, easily the biggest structure in the game, it meant recreating a version of the cathedral that didn’t actually exist at the time. Level artist Miousse spent literally years fussing over the details of the building. She pored over photos to get the architecture just right, and worked with texture artists to make sure that each brick was as it should be.

Feature image: Ubisoft