3D Scans of Notre Dame Captured in 2015 Could be Key to Reconstruction

By Karen L. Edwards, RCS Editor.

Construction technology could help architects, contractors and engineers answer questions and shorten the project timeline.

In 2015, the late Andrew Tallon, an art history professor at Vassar College in New York worked with colleagues to complete a 3D scan of Notre Dame Cathedral. The team used a Leica ScanStation C10 laser mounted on a tripod and spent five days mapping the building, recording more than one billion points of data. Tallon combined his scans with high-resolution panoramic photos to add color to the data.

John Russo, president and CEO of Architecural Reource Consultants and president of the U.S. Institute of Building Documentation told Engineering News-Record (ENR) that, “Having laser scans is critical in shortening the reconstruction time frame. 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 3D image of the cathedral contains all the dimensional information with very precise colors and measurements. Russo told ENR, "The scans are accurate enough to pick up the slight deviations in the structure, important from an engineering standpoint to understanding what the loads are doing through the structure.” According to Tallon, he once said that the scans were accurate to within five millimeters.

The Associated Press reported that French President Emmanuel Macron was calling for Notre Dame to be rebuilt within five years and in time for the 2024 Summer Olympics in Paris. Restoration experts have challenged that saying that it could take three times that long to complete.

While the 3D scan will prove invaluable to the reconstruction, it is still being debated if the restoration will be exactly as it was before the fire. BBC reported that French Prime Minister Edouard Phillipe called for “a new spire that is adapted to the techniques and challenges of our era.” An international design contest was launched for the design of a new spire.

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