The Association Mission Patrimoine Mondial (AMPM) is an organization created to manage the process for the city of Carcassonne (South of France) and its Sentinel mountain castles better known as “Les Châteaux Cathares”, to successfully obtain UNESCO World Heritage certification. Built in the 13th century, the combined site is an exceptional example of military architecture and construction from the time. As a part of the certification process, they need to provide 3D models that can identify known archaeological remains and possibly detect new ones for future exploration and make sure they are all protected by UNESCO classification. L’Avion Jaune, YellowScan’s sister organization, was mandated to fly the mission using the YellowScan Explorer LiDAR solution.
What is the Challenge?
The 7 fortified castles are spread out over 60 kilometers of mountainous terrain and not easily accessible by foot, so traditional archaeologic methods did not make sense for this phase of the project. A secondary objective of the project was to identify any new archaeological sites that were not previously identified and visible to the naked eye for further research as well as survey the primary 7 sites looking for ruins yet to be discovered.
Château de Montségur is a former fortress near Montségur, a commune in the Ariège department in southern France © L’Avion Jaune
Given the mountainous terrain and distance between the different castles, it was decided that a manned helicopter mission was the best profile to capture not only the photogrammetry resources for the sites, but also the point could data to render the 3D models. The team used the YellowScan Explorer, our first LiDAR solution that can be mounted on a light manned aircraft or helicopter as well as mounted on any professional UAV platform.
Our objective with Explorer, like all of our hardware platforms, is to offer the market a solution that strikes the right balance between size, range, accuracy and weight. Combined with 1-year unlimited technical support and training, our users will be ready to take full advantage of Explorer’s functionality and successfully complete their surveying projects.
YellowScan Explorer mounted on a helicopter © L’Avion Jaune
- 7 Castles surveyed
- 5 days of flight
- 3 flights
- 200meters from the ground
- 80 points /m²
- Ground data under canopy
- Using light helicopter and YellowScan Explorer
- 30-35m/s Flight speed
“Due to the difficult access and the density of the vegetation around the castles to be studied, airborne LiDAR was the only feasible option. The Explorer’s long-range capability and size allowed us to easily integrate the solution on the helicopter and survey the 7 castles, which are geographically distant, more quickly than if we had had to do it with a drone. Given the Explorer’s 5 echo capability it can easily penetrate the vegetation to recover the ground and generate the terrain profile, allowing the production of an accurate DTM thus giving the archaeologists a new set of mapping tools for their project.“
In total, 3 helicopter flights were necessary to map the totality of the castles spread over the departments of Aude and Ariège, in the South of France. The data recovered in fact did detect possible reliefs and ruins suggesting undiscovered human activity which will serve as a guide for future archaeological excavations. The mission also justifies an extension of the original protection zone planned for these historic sites.
By commissioning the complete 3D modeling of the seven sentinel mountain castles, the AMPM has improved its understanding of the historical significance of the area and increased its chances for a successful outcome to its UNESCO World Heritage application.
Photo of the Puilaurens castle © L’Avion Jaune
LiDAR pointcloud of the Puilaurens castle © L’Avion Jaune
Key Benefits of YellowScan Explorer
- YellowScan’s longest range scanner (600m)
- Single solution for multi-platform usability
- Applanix APX-20 IMU
- Can switch between 100 -500 kHC PRF depending on mounted vehicle
- 165Hz scanning frequency
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