” It’s a huge puzzle! “Livio de Luca, director of the Models and Simulations for Architecture and Heritage (MAP) laboratory at the National Center for Scientific Research (CNRS) is enthusiastic when he talks about the working group he coordinates. The researcher and his teams are responsible for grouping, cross-checking and studying all the digital data relating to the cathedral of Notre-Dame de Paris. ” We are retracing all the scientific knowledge that already exists, supplementing it by studying the debris, to constitute a “digital double” that will help in the reconstruction of the building. ”
N-DAME, the digital ecosystem
On April 15, 2019, the frame nicknamed the ” forest Of the iconic Notre Dame Cathedral in Paris went up in smoke. The spire collapsed like much of the roof. Following the fire, it was decided that the nearly millennial monument would be rebuilt ” Alike “. For this, digital data is at the heart of the site.
To drive “ the work of the century »In the words of the President of the Republic, the Ministry of Culture and the CNRS have established a partnership involving around 100 researchers. Among them, Livio de Luca’s team is tasked with managing the digital ecosystem of the project they have dubbed “N-DAME”. Bringing together written and iconographic documents, photos, videos and even 3D models, this set of tools allows you to analyze each component of the frame and the roof.
“Aioli”, a 3D semantic annotation platform
” For example, there are more than 60,000 images of the cathedral », Explains Livio de Luca. “Our tools make it possible to classify and share this information. Digital is for us the interdisciplinary link. Through multiple platforms, researchers can merge all of their knowledge in one place. The goal ? Compare the different “visions” of the building to get the most complete picture possible – depending on their temporality, the set of data collected and the material studied. All of this data is stored in an infrastructure called “HUMANUM”, loaned for the occasion by the CNRS. All project participants can drop their files there.
” Aioli Is one of the software at the heart of this project. Developed in Marseille upstream, this collaborative platform makes it possible to semantically annotate 3D images. It is therefore possible for researchers from all disciplines to name such and such an element according to their prism. “These textual annotations enrich and give meaning to these three-dimensional representations”, details Livio de Luca, delighted by the perspectives offered. “It is now possible to navigate between cathedrals, depending on the era! “
If the Provencal software was designed in 2017 by the MAP, an extension was developed especially for the site of the century. This is a viewer that compiles the different “3D scenes” of the cathedral from time to time. ” With “Aïoli”, we can therefore visit Notre-Dame de Paris in 2002, superimpose the layer dated 2016, then the one after the fire of April 2019. All with written captions to capture all the facets of the monument », Explains Livio De Luca.
In addition, the “OpenThesau” glossary
Legends are one thing, but everyone needs to understand each other. At the same time, the researchers developed “OpenThesau”, a tool for managing vocabularies specific to a particular discipline. This glossary with “strict criteria” allows them to communicate despite the specificity of the terms of each subject. Concretely, if one annotates an element with his vocabulary, the other can understand it thanks to the glossary. Inseparable, “Aïoli” and “OpenThesau” were designed together.
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In the same vein, “Archeogrid” is also used by Livio de Luca’s team. This intelligent photo indexing tool automatically classifies photos according to their dates, authors and research contributions. In iconography as in everything else, technology is welcome.
Lasergrammetry and digitization
First built from 1163 to 1345, then renovated in 1831 by the architect Eugène Viollet-le-Duc, the Cathedral of Notre-Dame de Paris has fed an extremely rich database. The first 3D lasergrammetry surveys were carried out in 2006, then in 2010 and 2012, by an American passionate about the building, Andrew Tallon. In 2015 and 2017, other private and public actors – the Graphic Art & Heritage company (AGP) or the German University of Bamberg – also undertook to digitize the Gothic monument. More traditional, specific surveys for the framework were carried out five years ago by one of the architects now in charge of the site, Rémi Fromont. ” These are fundamental resources for the digital restitution of the forest “Comments Livio de Luca, who works hand in hand with the architectural teams.
And the “digital heritage”?
” Our digital ecosystem is a collection of resources in time and space that can be enriched. This is real collaborative work! », Summarizes the CNRS researcher. The ambition of its working group is twofold: it is to bring together all the data, but also to compile all the possible scientific views on the monument on a single platform. According to Livio de Luca, the scientific contribution to this project is both to be ” support for reconstruction “But also of power” compare looks Simultaneously. ” We cannot dissociate the heritage object from how we perceive it. And digital technology has the power to memorize the perception of the same object and the collective adventure of which it has been the subject. ”
Leaving the trestles, the concrete blocks and the beams for a moment, Livio de Luca sees further ahead: “ The digitization of heritage is necessary. But we must now think about the patrimonialization of digital for future generations. Are we able to preserve our traces today? “