New technology assists protection of ancient cave murals

Experts are using advanced technology to provide wider access to the world-famous ancient murals in the Mogao Caves in Dunhuang, Gansu province.

Over the centuries, the murals, which can be dated back to about 366 AD, have been eroded by wind, sandstorms and human activity.

That poses many challenges for restoration experts, who also have to contend with the sheer scale of the 700-grotto site in the northwestern province.

In the 1990s, the Dunhuang Academy proposed the use of technology to record the murals and provide information for experts that would allow the treasures to be protected and passed down to future generations.

Du Juan, vice-director of the academy's new media center, said experts tried different ways of recording the images via film and videotape, but the results were unsatisfactory as the media were not suitable for long-term storage.

"Then, we made an attempt to use digital methods to help us repair and store the murals. In the initial period, around 1999, we started cooperating with colleges at home and abroad, such as Northwestern University in the United States," Du said.

"We set up a data center in 2006 and entered a period where we sought innovative techniques to help promote Dunhuang's cultural treasures. That search is ongoing. We held our first digital exhibition in 2014."

By last year, the academy had collected accurate images and data related to 229 grottoes, and had processed images from 156 of them. In addition, 143 grottoes were restored structurally, according to the academy.

"However, we experienced problems during the process. They were technical, related to the collection and processing of the images, and, more importantly, management of the files," Du said.

"In the past 30 years, we've only collected images of murals in 200 grottoes, so we still have a lot of work to do. Now, the biggest challenge is how to quickly and effectively record and collect all the murals in the main Mogao Caves and six others."

In 2017, to better overcome the technical challenges and provide greater access to the antique masterpieces, the academy began a strategic cooperation program with Chinese tech giant Tencent.

They initiated a fundraising campaign in June 2018, in which murals highlighting the concepts of "peace", "self" and "fearlessness' were collected into online "fortune kits", which provided inspiration when buyers shared them with friends, who could also donate to mural protection projects.

More modern methods were quickly employed. In September, 2018, the academy and Tencent released an audiovisual package that portrayed Yang Yuhuan, an imperial concubine known for her extraordinary beauty from the Tang Dynasty (618-907), in Tencent's Honor of Kings game, inspired by murals in Dunhuang that depict Yang.

In February, the academy, Tencent and People's Daily, jointly released a mini program on WeChat that allows viewers to browse the murals on their smartphones and purchase a small number of souvenirs.

"Users can explore the beautiful murals by their different colors and get to know their evolution during different dynasties," Du said.

"We added sound to some images so users can listen to stories and learn about the wisdom behind the murals. The mini program is now an important way for people to learn about Dunhuang. By February, we had 8 million registered users, with 37 million page views."

In March, the academy and Tencent agreed to extend their strategic cooperation program for three years, with the focus mainly on the use of artificial intelligence to help protection and repair work.

A statement released by the academy said it will employ AI technology to identify damage to the murals and classify the problems automatically and efficiently.

Tencent plans to develop an immersive full-frame system to allow experts from a range of academic fields to view the damage clearly so they can propose practical solutions.

Du said the academy will continue to use technology to help protect the ancient relics and employ innovative methods to encourage more young people to learn about Dunhuang's treasures.

"The technology allows people who can't visit Dunhuang to learn more about the antiques and help us pass on these splendid ancient cultural artifacts to future generations," she said.