Following the fire on April 15, 2019, Art Graphique & Patrimoine (AGP), a company specializing in the laser surveying and digitization of historical monuments, took part in the reconstruction of Notre-Dame de Paris through investment in the production of a building information model.
AGP’s use of Autodesk building information modeling (BIM) technology to create the 3D digital model of the building has played a key role in this project and will continue to contribute to heritage preservation in the future.
AGP: Experts in 3D Digitization and Heritage Preservation
Combining a passion for stonemasonry and historic buildings, AGP specializes in 3D digitization for preserving and promoting heritage. With over 25 years’ experience in France and abroad, AGP has built up unparalleled expertise, drawing on the talents of a multidisciplinary team of architects, engineers, stonemasons and restorers, graphic designers, developers, historians, and archaeologists.
AGP has established the highest standards in the digital rendering of heritage architecture. When creating archives for the preservation or reconstruction of a historical building, 2D and 3D rendering data is essential for keeping heritage alive, especially when it is endangered.
AGP also creates applications aimed at the general public, for educational and entertainment purposes. National landmarks such as the Pont Avignon and the Villa Majorelle in France and the Krak des Chevaliers, a crusader castle in Syria, can now be visited virtually thanks to the point cloud and BIM models AGP has built.
The 3D digitization of a historic building is an extraordinary task. Each individual monument has its own distinctive features that determine the techniques and conditions required in the scanning process.
1. Onsite Data Collection
The 3D data is then collected onsite, either by lasergrammetry from the ground or photogrammetry from the air, sometimes both. Using a laser scanner or a drone, the AGP engineers take billions of measurements, all delivered to millimetric accuracy.
2. Scan Analysis
Next, the scans are processed, cleaned, stitched, merged, and analyzed by the experts at AGP to ensure that the digital model is as close as possible to reality.
3. Data preparation and 3D Modeling
The collected point cloud data is then processed and prepared in Autodesk ReCapPro. Once the data is imported in Autodesk Revit, AGP creates a BIM model of the cathedral which includes data-rich objects such as walls, roofs, columns, floors, and so forth.
4. Documentation and Data Extraction
Technical documents such as plans, elevations, sections, axonometric views, shop drawings, and perspectives, as well as precise material quantities and data, can be extracted from the BIM model.
5. Digital representation
Accessible to any project stakeholder, the BIM model includes the specificities of the building, as well as the nature and the quantities of materials. Thanks to this rich model, professionals in architecture, engineering, and construction can study the geometry of the asset, take exact measurements, and assess renovation costs.
Savoir Faire Built Over Time
Having studied Notre-Dame for more than 25 years, AGP boasts an unparalleled database of information. In 1993, the company carried out the first digital survey of the cathedral to produce geometrical views for maintenance purposes. In 2010, AGP set out to conduct additional surveys of the building using laser scanners as part of its collaboration with Belgian art historian Andrew J. Tallon.
Although survey techniques are similar from one building site to another, the 3D BIM modeling varies from one construction to the next, based on each building’s critical features. For AGP’s experts, the real challenge lies in their ability to digitally render the structural deformations specific to each monument.
The Power of BIM
From the perspective of preserving the built environment for future generations, BIM enables team to capture the physical world and to create digital assets. These data-rich BIM models empower asset managers and owners to anticipate future renovations. Coupled with a computer-aided management and maintenance system and connected to sensors, owners are able to take this data a step further, allowing them to plan and monitor the operation and maintenance of their monuments and buildings.