Notre-Dame 3D Scanning & Post-Fire Reconstruction
Emergency 3D scanning operation
FIRST STAGE OF THE RECONSTRUCTION
Following the 2019 fires, the MEMORIST team, in collaboration with the company FARO, carried out an emergency operation to safeguard Notre-Dame on the instructions of the Lead Architectes in charge of the historical monuments, the regional directorate of cultural affairs (DRAC), the Île-de-France conservatoire of historic monuments (CRMH), and the prefect of the Île-de-France region. The operation involved conducting a precise 3D survey of the building in its post-fire state in a single day to assess the damage.
Data acquired from these initial post-disaster 3D surveys can be compared with pre-fire data to provide useful information for reconstruction and ongoing investigations. The complete MEMORIST dataset will provide all trades with a reliable database of 3D measurements, images and technical documents relating to the cathedral, particularly the most severely damaged sections.
Billions of points covering the entire cathedral
Over the course of 25 years, MEMORIST has carried out several 3D surveys of the cathedral using laser scanning – lasergrammetry – and photogrammetry techniques. The assembled data has enabled the reconstruction of scans (point clouds) of the roof, the framework (the “forest”) and the spire – elements that were lost in the fire.
For the “forest”, this comprises:
- 150 scans with millimetric precision, totalling three to five billion points.
- The exceptional point density (approximately one to two points per mm²) enables unparalleled reproduction of the framework and roof, including the spire. Art Graphique & Patrimoine (AGP) supported Andrew Tallon in 2010, partnering with him on his survey campaign for Notre-Dame. This campaign, achieved with millimetric accuracy and centimetric density, made it possible to obtain the building’s general volumes as part of his research into cathedral construction systems.
For the cathedral as a whole:
- The complete set of scans of Notre-Dame carried out by AGP over several years contains approximately 50 billion points.
A BIM model for the restoration of Notre-Dame
Restoring Notre-Dame will require a combination of traditional building techniques and modern, digital construction methods.
Starting today, BIM committee of the French association of companies specialising in the restoration of historic monuments (GMH), comprising managers and staff from approved contractors, will begin work on the BIM model of Notre-Dame with the support of Autodesk.
MEMORIST, a member of the GMH and its BIM committee, is coordinating the development of the cathedral’s BIM model in collaboration with the consortium’s trades and Autodesk.
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