Digital innovation supports cultural heritage care
The historic Notre-Dame Cathedral in Lausanne, built between the late twelfth and early thirteenth centuries, remains one of Switzerland’s most significant Gothic landmarks. Over the centuries, the structure has been modified, extended and repaired, with the lantern tower alone undergoing multiple redesigns. The stone used across the building, common throughout the Swiss plateau, is vulnerable to moisture-related deterioration, making long-term conservation an ongoing challenge for specialists responsible for safeguarding the monument.
Researchers at ETH Zurich have been exploring how advanced digital technology might help conservators manage this challenge more effectively. Their work forms part of the Heritage++ research project, which investigates how extended reality and artificial intelligence can be applied to the restoration and maintenance of historic structures. The project places particular emphasis on developing digital tools that support professional decision-making while also expanding public understanding of built heritage.
A central product of this research is an immersive digital co-pilot designed to assist conservators during on-site inspections and maintenance planning. The system uses spatial computing to analyse physical surroundings and overlay digital information onto the real environment through tablets or extended reality headsets. Instead of relying solely on traditional drawings, written documentation or on-site interpretation, specialists can access detailed digital insights while standing directly in front of the structure they are assessing.
Researchers have shown how structural analysis data can be integrated into extended reality environments, allowing users to observe how stresses and forces operate across the building. This approach helps experts from different disciplines understand structural behaviour in a more intuitive way. It also offers members of the public the opportunity to explore complex engineering issues without the need for advanced technical knowledge.
The cathedral serves as the primary case study for the development of the co-pilot. The project began with the creation of highly accurate three-dimensional models generated from laser scanning and photogrammetry surveys. These models were then enhanced with detailed information about individual stone blocks, including their mineral composition, age and degree of degradation. Such data allows conservators to identify where each stone originated, when it was installed and how it has weathered over time.
Contributors from the University of Lausanne supplied geological information that helped the team map the stone varieties used throughout selected areas of the cathedral. This multimodal mapping remains a work in progress, with researchers aiming to complete it over the coming years. Visitors using a tablet or extended reality device can view sections of the building and examine precise digital overlays that provide insight into the condition of each element.
During inspections, the co-pilot enables professionals to observe both visible damage and underlying issues that may not be immediately apparent to the naked eye. Once the system highlights vulnerable areas, specialists can determine appropriate interventions. The tool serves as a reference point, ensuring that decisions are supported by consistent data rather than relying solely on memory or on-site impressions.
Climate-related deterioration forms a major focus of the ongoing research. Although current conservation practice emphasises the preservation of original material wherever possible, this aim becomes increasingly complex as weather patterns shift. Water remains the key driver of sandstone degradation, particularly when wind-driven rain leads to rapid wetting followed by sudden drying. These cycles, often triggered by extreme weather events, can cause swelling, freezing damage or salt crystallisation within the stone.
ETH Zurich researchers have been monitoring wind-driven rain, the local microclimate and moisture behaviour in the cathedral’s walls through a long-term network of sensors. By analysing how environmental factors influence decay, the team aims to build predictive models that can help conservators anticipate future patterns of damage. These models consider not only the natural ageing of materials but also the expected effects of climate change, such as more frequent storms and intense rainfall.
With these insights, professionals will be able to design restoration strategies that remain effective under future conditions. The ultimate goal is to improve the durability of repair measures so that they offer long-term protection despite increasing environmental stress. Such work is vital for practitioners who must continually balance authenticity with resilience.
Although digital modelling is not new in the field of cultural heritage, the Heritage++ project advances the practice by integrating knowledge from architecture, materials science, history and conservation into a single interactive platform. This integration also allows for the inclusion of practical experience gained by on-site conservators, creating a richer and more accurate record of the monument’s condition.
Researchers believe the co-pilot developed for Lausanne Cathedral could eventually be applied to other stone monuments, including castles, monasteries, bridges and other historic structures across Europe. Over time, the platform may broaden to include buildings made from materials beyond sandstone, offering a versatile tool for heritage managers worldwide.
The project aligns with the views of local conservation professionals, who see digital technologies becoming increasingly central to their work. While protecting historic sites requires careful stewardship and respect for original craftsmanship, modern tools can provide valuable support by revealing structural weaknesses, tracking long-term changes and guiding targeted interventions that minimise disruption to the fabric of the building.
As part of the cathedral’s 750th anniversary celebrations, researchers released a public-facing app that uses extended reality to share insights from the Heritage++ project. Through the app, visitors can learn about the building’s history, understand ongoing conservation efforts and see how restoration decisions are made. The platform combines scholarly resources with video explanations from specialists, all visualised through the same 3D modelling and augmented reality system used by conservators.
Plans for the next phase of the co-pilot include integrating a large language model capable of extracting information from technical literature and video documentation. This enhancement would allow professionals to access relevant guidance directly during inspections. In future, the public could also use this feature to ask questions about the cathedral’s restoration, deepening engagement with heritage care.
The research at Lausanne highlights how digital innovation can support the preservation of historic monuments while maintaining a strong connection to their cultural and architectural significance. By combining advanced technology with traditional conservation values, the project aims to ensure that structures like the Notre-Dame Cathedral continue to endure for generations.
