On the road to smart archaeology
Author: Nikita Chunakov
Trade routes from ancient and medieval times crossed the territories of the modern-day Republic of Ingushetia in the Russian Federation. The Silk Road was the main trade route crossing the North Caucasus plains of present Ingushetia. The route often underwent changes as it crossed numerous territories with radically different political relationships at different points in time.
Local residents took part in trading and made profit from watching over the trading routes. To control the Silk Road corridors and protect inhabitants from conflict, fortified tower settlements appeared along the caravan routes.
There are 40 fortified tower settlements in the foothills of the Ingushetia plains. One of these tower settlements is located in Bisht, a high-mountain village, in the Dzheyrakhsky District of the Republic of Ingushetia.
To create a 3D model of the sturdy fortresses with stone towers and its surrounding area for modelling and reconstruction of the village objects, Noviy Proyekt, an experienced Russian construction company, geared up with Geosystems surveying equipment for the task.
A dream for a tourist, a challenge for a surveyor
The ancestral towers in the Ingushetia mountain territories are the republic’s main tourist attractions. The heritage marvel sitting on the marvellous Caucasian mountains has an average elevation of 1,750 metres and a change in elevation of approximately 300 meters.
Noviy Proyekt had to gear with equipment that would resist abrupt weather changes from +16ᵒ Celsius to -4ᵒ С. The survey of approximately 32 hectares was conducted in the autumn to avoid the heavy summer foliage and early winter snow.
Due to the environmental conditions and location of the site, the two surveyor specialists required equipment with the following specifications:
- Light weight
- High level of dust and moisture protection
- Minus temperatures resistant
- 3D scanning and surveying view of results right on the field
- A tool that enabled as many tasks as possible.
Laser scanning in archaeology
To survey in this environment with the requirements needed, the Leica Nova MS60 MultiStation was chosen, allowing to laser scan at a distance of up to 1,000 metres.
“It was a pleasure to work with Hexagon Geosystems Russia. We worked with great enthusiasm with the new equipment. I am still amazed from the speed and quality of the laser scanning device. It has really sped up the execution of our tasks,” said Vitaliy Galaktionov, chief surveyor at Noviy Proyekt.
One of the advantages of laser scanning is the ability to survey even when direct access to the facility is obstructed. The georeferenced trigonometrical surface generated with the point clouds was transferred to architects for analysis of:
- Two tower complexes
- Several residential stand-alone towers
- Two cemeteries
- A large group of sepulchral vaults
- Burial grounds
- A sanctuary.
The surrounding area for the structures was laser scanned using larger spacing, with a distance range of 10 to 300 metres depending on visibility conditions. During scanning, the laser beam hit both the ground and vegetation, but using specialised filters for post-processing the data array, it was possible to select only the points on the ground. Surveying such vast territories with a total station, using both reflector and reflectorless distance measurements, would have taken substantial time and required two specialists for this task.
One of the challenges of architectural surveys is capturing facades with detail – much depends on the quality and completeness of the survey. Using the most complete data array in the form of points clouds, ensures data integrity with all necessary captured points. Aspects, such as stone size in the brickwork, flange size for the beams, and the geometry of cracks were captured with the MS60.
From outer space to the office
When working on the mountains, it is necessary to be sure of the quality of the results, which is why the Leica Viva GS16 GNSS smart antenna was selected. The smart antenna, with leading RTK technology, was integrated with HxGN SmartNet, a 24/7 HNSS network RTK and DGNSS correction service to quickly determine points with centimetre-level accuracy in an area covered with trees.
A robust communication to a correction service is needed but cannot always be relied upon. Despite a narrow window for satellite visibility and poor coverage of the area by mobile network during the survey, the highly-sensitive board and computer core of the smart antenna delivered reliable centimetre-level positioning. Particularly suitable for this kind of low-populated area with unstable RTK communication, SmartLink fill helped Noviy Proyekt specialists to retain the positioning accuracy even if the RTK data link was lost.
The satellite-corrected GS16 smart antenna was used for:
- Surveying the outline of road edges, buildings and ruins
- Coordinating pillars in the local coordinate system
- Setting and orientating of the robotic total station.
Approximately 2,000 points and linework were collected, with polylines and splines drawn directly in the field, facilitating subsequent office processing.
The Leica Captivate software on the Leica CS20 field controller and the MS60 made possible to check the survey completeness, transfer projects from one instrument to another, and make quick decisions directly on the field.
Smart workflows for archaeologists
Using an integrated approach to archaeological tasks allows to collect the most complete and reliable data on objects. Surveying technologies paired with easy-to-use software and the largest reference station network, permit to position, visualise, georeference and preserve any cultural asset for future generations.