The site of Mes Aynak is located in the province of Logar, a politically unstable region south of Kabul, in a sector still being cleared of landmines. The soil here contains numerous remains from the Kushan Empire – a Buddhist civilisation at its peak from the 1st to 3rd century A.D. 12 extremely wealthy monasteries have been identified in the area, some of them containing hundreds of sculptures and many frescoes. Unfortunately, the site is scheduled to be completely destroyed because the ground beneath it contains one of the largest unexploited reserves of copper in the world.
The cultural richness of the site and its planned destruction meant that a particularly efficient strategy was required for the 3D recording of the site. However, as with any digitisation project, we were subject to a large number of constraints. On one hand, the political instability of the region meant that we could be present for only 10 days at a time; a significant problem given the very steep nature of the terrain in the study area. On the other hand, the presence of landmines made some parts of the area inaccessible by foot. In such circumstances, digitisation by drone was clearly the best solution. This process enabled the production in a few days of a very accurate topography of all parts of the site, even those still affected by landmines, but also the reconstruction of the smallest architectural and decorative details.
Following a request from the DAFA (Délégation Archéologique Française en Afghanistan – the French Archaeological Delegation in Afghanistan), our team’s drones have scanned the site of Mes Aynak annually since 2010, during the excavations carried out by the Afghan Institute of Archaeology.
Every year since 2010, a new 3D model of Mes Aynak has been reconstructed on the basis of site data acquisition campaigns carried out by our team using drones in 2010, 2011, 2012, 2013 and 2015.
By combining these models in a single space, it is possible to generate an evolving model which retrospectively documents the progress of the excavations over the last six years.
By carefully superimposing these models sector by sector, before and after excavation, it is possible to retrospectively calculate the relative heights and depths of the levels discovered. In this way, it is possible to reconstruct the excavations, enabling reinterpretation and measurements to be carried out at a later date.
THE SITE IN DETAIL
Up to now, 12 monasteries have been discovered on the site of Mes Aynak, distributed across a steep, rocky and mountainous landscape. The excavation of these monasteries has revealed a large number of paintings and clay sculptures (primarily Buddhas).
Detailed digitisation is essential to understanding and archiving the site. The process must be carried out simultaneously on several scales, from the most global to the most granular:
- Landscape scale: topography of the mountains
- Architecture scale: monasteries, workshops, habitations
- Decorative detail scale: sculpture, paintings
To achieve these three levels of digitisation, we have created a method for the multiscale acquisition of data which records details in millimetres for the relevant areas of the sculptures, centimetres for the architecture and decimetres for the natural topography. By using images taken by drone, it is possible to automatically adjust the degree of precision of the reconstructions (mm, cm or dm) depending on the distance between the appliance and the object scanned.
Photogrammetric techniques then make it possible to combine all of these scales of representation in a single 3D model, known as a multiscale model. This model acts as a documentary reference, from which the documentation used by the archaeologists can be extracted: sections, plans, detail plans etc.