The Images That Could Help Rebuild Notre-Dame Cathedral

by Alexis C. Madrigal, The Atlantic

The work of Vassar College’s Andrew Tallon could help restore Paris’ fire-damaged Notre-Dame Cathedral, thanks to detailed scans he and Columbia University’s Paul Blaer took of the landmark in 2010.

Before the tragedy seen all around the world, flames leaping from the top of Notre-Dame Cathedral, there was a smaller one, thousands of miles away in upstate New York.

Andrew Tallon, a pioneering architectural historian and father of four, died on November 16, 2018, from brain cancer. He was 49. He had dedicated his life to the study of medieval architecture, its mysteries and resonances, blending in his interest in technology to create novel ways of studying centuries-old buildings.

“When you’re working on medieval buildings, it’s difficult to have the impression you can say anything new. They’ve been looked at and written about for ages,” Tallon told a documentary crew in 2015. “So I’ve been using more sophisticated technology these days to try to get new answers from the buildings.”

Tallon and Blaer used a Leica ScanStation C10 to laser-scan the building over five days, and also captured high-resolution panoramic photos to map onto three-dimensional (3D) forms that the laser scanner could generate.

The accumulated information consists of 1 billion data points, structured as “point clouds,” which software can render into images of the 3D space. A full digital reproduction can be created by stitching these images together and mapping the photos onto the precise 3D models.

Laser scans like Tallon and Blaer’s represent a significant development in the restoration of historic buildings. “Having the scans is incredibly important in any kind of reconstruction,” said Raymond Pepi, the president of Building Conservation Associates, which was the restoration consultant for St. Patrick’s Cathedral in New York City.

The Massachusetts Institute of Technology’s John Ochsendorf said the data collected by Tallon and Blaer is “essential for capturing [the structure] as built geometry.”

But as the cathedral officials and architectural authorities in France and around the world begin to consider what to do, they will come looking for the laser-data files that Tallon created. Blaer estimated that, despite the high resolution of the scans and panoramic photographs, the files would be roughly a terabyte, small enough to fit on a single hard drive, but unlikely to be stored in the cloud. All those data now exist on a single disk, a tiny portal into the past, which is sitting somewhere on Earth. Blaer thought it might be in the hands of Tallon’s students at Vassar. But Ochsendorf thought the data were most likely with the rest of Tallon’s archive, in the possession of his widow, Marie, who held Andrew in her arms as he died. Read the full article.