Digital technology turns century-old Chinese grottoes vibrant

In a cave at the Yungang Grottoes, an ancient Chinese Buddhist site in Datong city, north China's Shanxi Province, several technicians were taking close-up photogrammetry and collecting image data with instruments such as HD cameras, station scanners and 3D laser scanners.

"We are collecting digital information about the Yungang Grottoes, which will provide important data support for the long-term conservation of the historical site," said Zhang Zhuo, secretary of the Party committee of the Yungang Grottoes Academy.

Excavated in the Northern Wei Dynasty (386-534), the Yungang Grottoes have a history of over 1,500 years. The cave relics are prone to weathering as the historical site is located in an open environment.

"The ongoing digital program is a basic project for the site to obtain accurate data for permanent preservation and perpetual use," Zhang said.

During information collection, subtle damage and potential risks could be discovered and then been timely fixed and eliminated, Zhang said, adding that the high-precision data and information collected would be digitalized to restore the grottoes in a database, providing data and image support for the protection, repairing and even reconstruction of the caves.

A number of projects have been launched at the Yungang Grottoes in recent years, including cave maintenance and investigation, construction of monitoring systems, waterproofing projects, digital collections of cultural relics, and 3D printing. The application of digital technology has made the protection work more precise, which helps realize the coordinated development of relics reservation and cultural research.

Digital technology is also bringing more people closer to the splendid Yungang Grottoes.

The Cave No. 12 of the grottoes, known as a "music cave", contains dozens of carvings of ancient musicians and musical instruments

In collaboration with Zhejiang University, the academy collected high-fidelity digital information with 3D laser scanning technology and made a 1:1 replica of the "music cave" by 3D printing. All the clone parts are assembled like building blocks, so as to make transportation easier.

More projects have been implemented based on cave digitalization, including digital modeling, construction of the 3D information system and digital sampling. The academy also replicated Caves No. 3, No. 12 and No.18 of the same size in cooperation with institutes such as Zhejiang University and Wuhan University.

The Cave No.3 and Cave No.18 replicas are now respectively placed in Qingdao, east China's Shandong province and Beijing University of Civil Engineering and Architecture, as promotion landmarks of the grottoes. The Cave No.12 replica, which can be disassembled, has been exhibited at Zhejiang University and Shanghai Powerlong Museum, and will start its tour to Shenzhen, south China's Guangdong province for display this year.

Ning Bo, director of the digital protection center of the Yungang Grottoes Academy, introduced that the grottoes were the first in the world to make 1:1 replicas for super large cultural relics using 3D printing and block-style assembly technologies.

Remarkable progress has been achieved in enabling the movable display of immovable cultural relics, which marks a solid step of the Yungang Grottoes going global, Ning remarked.

Besides, the Yungang Grottoes have also made the cultural relics online using virtual reality and other cutting-edge technologies, which helps present the century-old Chinese grotto art to more people around the world and makes the cultural relics vibrant in the digital era.