Digital tech plays key role in protecting Great Wall

LANZHOU — Authorities in Northwest China's Gansu province recently completed the building of a three-dimensional database to digitally map the Great Wall in order to ensure better protection.

The database contains all the information collected through unmanned aerial vehicle field scans and air remote sensing technology and generates millimeter-level high-precision 3D images of several sections of the Great Wall in Shandan county, in Zhangye, Gansu, according to Bai Yuzhang, a staff member of the Shandan cultural relic protection bureau.

The Great Wall sections in Gansu stretch 3,654 kilometers. Over the past few years, the Gansu provincial cultural heritage bureau has implemented more than 30 protection projects, utilizing digital technology as a new approach.

The Shandan section stretches over 200 km, which was mostly built from the Han Dynasty (206 BC-AD 220) to the Ming Dynasty (1368-1644) and is considered well-preserved. The existing sections in Xiakou village are the main components.

"The Great Wall in Xiakou has suffered from serious weather erosion over an extended period of time. It now appears to have peeling, porosity, cracking and other issues," says Bai, adding that other relics, such as ancient street buildings and beacon towers, have also suffered damage of varying degrees.

During the past two years, the local government has carried out several projects to restore the Xiakou section and started the digitalization project in 2021.

The technical team used UAV photography and remote sensing mapping technologies to take photos of the Great Wall and the surroundings, covering an area of about 25 square kilometers, and generated panoramic 3D models based on data analysis. These digital technologies can collect accurate data in a short period of time, says Lin Haitao, who works with the project's technical team.

The 3D models precisely reflect the textures on the surface of the wall with a resolution of up to 2 millimeters, Lin adds.

After more than a year of data collection and analysis, the database has been completed and the system is in the trial run stage and preparing for final acceptance.

"The advantage of digitalization is that it can break the limitations of time and space so that users have enough access to understand the rich historical and cultural connotations of the resources," Bai says.

"The database is not only precious historical materials of cultural relics, but also the foundation for future research, protection and application of the Great Wall heritage," he adds.

This project is among the first batch of digital protection projects of the Great Wall in Gansu, providing a new approach for heritage protection and research, says Zhang Li, a tourism official from Shandan county. "Advanced digital technology helps us protect, discover and explore the splendid cultural treasures left by ancient people," he adds.