Using holograms and real-time force analysis, researchers show how AR can transform how we inspect, preserve, and protect ancient structures like Lausanne Cathedral.
Study: Augmented Reality for Structural Inspection of Historic Monuments: The Case of Lausanne Cathedral. Image Credit: The Mount Bird Studio/Shutterstock.com
Published in the International Journal of Architectural Heritage, a team of researchers has been exploring how augmented reality (AR) technology can be used to support the structural inspection of heritage sites.
In the study, the team focused on the Lausanne Gothic Cathedral in Switzerland, demonstrating how AR enhances preservation efforts by improving data visualization and strengthening collaboration across conservation, engineering, and architectural teams.
How AR is Shaping the Future of Structural Monitoring
As a concept, AR overlays digital information onto the physical world, allowing users to interact with complex data in a spatial context.
In relation to the architecture, engineering, and construction (AEC) sector, recent innovations have meant that this can be taken one step further by enabling the projection of holographic models onto real structures, totally transforming how professionals engage with built environments.
In heritage conservation, for example, AR serves as a valuable bridge between technical analysis and on-site preservation work.
By combining data collection techniques like laser scanning and photogrammetry with intuitive AR interfaces, specialists can assess the structural condition of historic buildings and better understand patterns of material degradation. Tools such as the Microsoft HoloLens enhance this workflow by placing structural data and historical context directly within the user’s field of view - reshaping how historic sites are inspected, documented, and maintained.
A Two-Stage Approach to Data Collection
This study focused on using AR to inspect the Lausanne Cathedral, a major Gothic monument constructed between 1170 and 1235. The team developed an augmented inspection platform by integrating structural engineering, material science, and conservation expertise. Their model combined structural analysis with historical and material information, helping experts visualize structural integrity and areas of degradation.
The methodology followed a data-driven process, beginning with extensive data collection using terrestrial and aerial laser scanning, producing a point cloud of approximately 18.9 million points. This dataset was processed into high-resolution three-dimensional (3D) models of the cathedral’s structural components. Additional information was integrated, including material characterization (such as the density of local sandstone and tufa) and known degradation mechanisms affecting different zones of the structure.
The study also considered the cathedral’s historical evolution, which was constructed in three major phases, with later repairs to the lantern tower and flying buttresses, helping to contextualize the structural challenges and vulnerabilities.
To enable interactive use of the models, researchers employed Unity®, a leading 3D development platform, and designed the AR application for Microsoft HoloLens 2® headsets. This setup allowed users to visualize structural analysis directly on-site, creating an immersive experience that combined real-world observation with digital insights.
The structural assessment incorporated Thrust Network Analysis (TNA), a technique suitable for masonry structures, enabling the simulation of force distribution and evaluation of the cathedral’s stability. TNA was used to identify internal compressive load paths and estimate Geometric Safety Factors (GSFs) across various cross-sections of the building. The AR-based platform provided a powerful tool for exploring the cathedral’s structure in real-time while considering its historical context.
Findings: Understanding Structural Vulnerabilities
The study showed that AR made a real difference in how historic buildings are inspected, giving users instant access to structural data right where they need it. At Lausanne Cathedral, the platform helped experts get a much clearer understanding of the building’s condition, revealing some real concerns, particularly with the clay-bearing sandstone, which doesn’t hold up well to moisture and pollution.
One of the key findings was that certain parts of the cathedral, especially those exposed to wind-driven rain, need regular monitoring. These areas are more prone to weather-related wear, making effective water management crucial. Thanks to AR, conservators could see these vulnerable spots directly through the headset, allowing them to make more confident, informed choices about where and how to intervene.
The structural analysis, using Thrust Network Analysis (TNA), also uncovered serious horizontal forces in parts of the building - most notably in the flying buttresses. The main vault was found to exert a peak thrust of 199.1 kN at a critical point (gridline 5), where the Geometric Safety Factor (GSF) came in at 2.9. That’s just below the recommended safe value of 3.0 for masonry structures.
To fix this, the team installed a strut-and-tie retrofit, essentially a combination of a steel tie and an angled compression strut. This clever solution boosted the GSF to 5.0 and reduced the sideways force on the walls by 38 %, giving the structure much-needed extra stability.
But the benefits of the AR platform went beyond just calculations. It helped people actually see what was happening inside the building, such as how forces moved, where weaknesses were, and how materials were holding up. Users could then explore the structure using hand gestures and eye tracking, access detailed information on specific components, and even mark areas of concern like cracks or erosion spots.
That level of interactivity made it easier for everyone (engineers, architects, material scientists, and historians) to stay on the same page and work together more effectively.
Practical Applications in Heritage Conservation
The findings from this research have wide-reaching potential for preserving other historic structures - think bridges, castles, monasteries, and similar buildings made from vulnerable materials. The AR inspection platform developed for Lausanne Cathedral can be adapted to different heritage sites, where having real-time access to structural data could make conservation efforts more precise and efficient.
Looking ahead, combining AR with large language models (LLMs) opens up even more possibilities. For instance, users could ask questions about specific building elements right through the AR interface and receive detailed, context-aware responses on the spot. Beyond structural assessments, AR could help visualize upcoming restoration work, monitor long-term material changes, or even engage the public through interactive storytelling that explains what’s being preserved and why it matters.
That said, the researchers point out a few current limitations. AR headsets aren’t yet widely accessible, and aligning holograms across large or complex heritage sites still poses technical challenges. These issues can affect accuracy and cost-effectiveness, but both hardware and software are improving rapidly, making these barriers likely to shrink over time.
Conclusion: The Future of AR in Cultural Heritage
This study offers a strong case for how AR can support the future of heritage conservation. By blending advanced digital tools with traditional preservation know-how, it lays out a practical framework for assessing and managing historic structures more effectively. Just as important, it highlights the power of interdisciplinary collaboration and how bringing together architects, engineers, conservators, and historians can lead to better, more informed decision-making.
The ongoing development of a “digital co-pilot” for Lausanne Cathedral shows how AR can enhance expert analysis while also making the cathedral’s story more accessible to the public. Still, the researchers are clear-eyed about the limits in the fact that current AR models are based on static conditions, and capturing real-time stress and movement will require integrating live sensor data or full digital twin systems.
Even so, as AR continues to advance, it’s set to play an increasingly valuable role in protecting and understanding our most important cultural landmarks.
Journal Reference
Avelino, R, M., & et al. (2025, November). Augmented Reality for Structural Inspection of Historic Monuments: The Case of Lausanne Cathedral. International Journal of Architectural Heritage. DOI: 10.1080/15583058.2025.2578318, http://dx.doi.org/10.1080/15583058.2025.2578318
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