Researchers conducted digital collection in the Mogao Grottoes. Courtesy of Dunhuang Academy
Tourists visit the Mogao Grottoes. Photo by Wang Yi (People's Vision)
Slowly climb up the scaffolding, open the toolbox, hold your breath, gently pinch the ear ball and carefully blow off the dust on the mural, grouting and pasting, rolling ...... At more than 8 o'clock in the morning, Fu Youxu, a mural restorer, rushed to Mogao Grottoes early to start a new day's "wall-facing" work. He has been engaged in cultural preservation work for 37 years, and the area of murals saved by his "wonderful rejuvenation" has exceeded 2,000 square meters.
Located at the western end of the Hexi Corridor in Gansu Province, Dunhuang Mogao Grottoes has 735 caves, 45,000 square meters of murals, and more than 2,400 colored sculptures, known as the "treasure house of human culture and art".
This year marks the 80th anniversary of the founding of the Dunhuang Academy. Over the past 80 years, generation after generation of Dunhuang people have adhered to the Mogao spirit of "sticking to the desert, being willing to contribute, having the courage to take responsibility, and forging ahead", and have devoted themselves to the protection and restoration of Dunhuang grottoes, the study of Dunhuang studies, and the dissemination and promotion of Dunhuang culture.
Today, the Dunhuang Academy is fully responsible for the management and protection of the Mogao Grottoes in Dunhuang, the West Thousand Buddha Grottoes, the Yulin Grottoes in Guazhou, the Maijishan Grottoes in Tianshui, the Grottoes in Yongjing Bingling Temple and the North Grottoes in Qingyang, forming an operating pattern of "one courtyard and six places", and has developed into a cultural and museum management institution with the largest number of world cultural heritage and the widest cross-regional scope in the mainland, as well as the largest research entity of Dunhuang Studies.
Innovative technology applications
Build a scientific protection system
In Fu Youxu's toolbox, there are hundreds of mural restoration tools. "Brushes, cotton balls, syringes, each with a unique purpose." Fu Youxu said that the construction of the Dunhuang Grottoes began in the fourth century, and the murals in the caves have a history of thousands of years, which are both fragile and precious. For this reason, he always works with care, often taking more than 10 days to repair 1 square meter.
How effective is this slow work? Open the mobile phone album for comparison, the mural before the restoration, the faces of the characters are blurred, the outline of the landscape is broken, and through the cracks, you can even see the wall behind the mural, which is almost about to fall off. After the restoration, Feitian has a beautiful face, a cloud belt flying on his back, and a cloud fluttering under his chest, with a beautiful and imposing posture.
Mogao Grottoes is located in the desert Gobi, and the drought of the climate is an important factor in the preservation of the murals, but the strata contain a large number of soluble salts, which constantly deliquescent and crystallize with the change of temperature, migrating to the murals, and then harming the murals.
In order to overcome this problem, the cultural relics protection team of the Dunhuang Academy spent 7 years, experimented with more than 80 kinds of materials with different blending ratios, explored the technology of "grouting and desalination", and completed the restoration in Cave 85 of Mogao Grottoes. While curing the "cancer" of murals, the Dunhuang Academy overcame many difficulties and gradually explored and developed key technologies for the restoration of mural diseases, such as nail re-pasting and hollow drum grouting, established a set of scientific procedures for the protection of murals, and contributed to the promulgation of the "Guidelines for the Protection of Chinese Cultural Relics and Historic Sites".
"The concentration of carbon dioxide in Cave 66 has increased, so pay attention to reasonable evacuation of tourists." In the grotto monitoring center of the Dunhuang Academy, a huge screen updates the monitoring data of the Mogao Grottoes and the microenvironment in real time, and the temperature, humidity, carbon dioxide concentration and other information in the cave are clear at a glance.
"Visitors to the cave cause changes in temperature, humidity and carbon dioxide concentrations, and our task is to keep these values within a reasonable range. When the safety value is exceeded, a reminder is issued in time to allow the cave to 'rest'. Zhang Zhengmo, deputy director of the grotto monitoring center of the Dunhuang Academy, said that each open cave is equipped with monitoring equipment, which is equivalent to a real-time "physical examination" for the cave.
Today, the Dunhuang Academy uses environmental monitoring equipment to obtain environmental conditions inside and outside the cave in minutes. "The use of the Internet of Things, wireless sensors and other technologies for real-time monitoring can not only warn potential risks, but also provide reliable data support for preventive protection." Zhang Zhengmo said that at present, the institute has built the first provincial platform for monitoring and early warning of cave temples in China, and has realized the sharing of monitoring information in six grottoes affiliated to the institute.
In the past 10 years, the Dunhuang Academy has successively implemented more than 130 projects such as the protection and repair of the grotto itself, the reinforcement and management of the cliff body, the improvement of the environment, and the construction of safety and fire protection, so that the protection of the cultural relics of the six grottoes has been fundamentally improved.
Simulation of various climatic conditions such as temperatures ranging from minus 30 degrees Celsius to minus 60 degrees Celsius, relative humidity from 10% to 90%, and wind, rain, snow, and sun exposure throughout the year...... As the only large-scale physical simulation platform for all climates in the field of cultural heritage in mainland China, the multi-field coupled environmental simulation laboratory plays an important role in the research and development of cultural relics protection materials, disease mechanism research, preventive protection and protection technology research and development.
"In a multi-field coupled environment simulation lab, it is possible to achieve a 'race against time'." Pei Qiangqiang, a young researcher at the Dunhuang Academy, said that taking the arid environment as an example, it only takes more than a month to simulate an annual cycle, which greatly shortens the research cycle.
From rescue protection to preventive protection, from murals and painted sculptures to earthen ruins and cave temples, with the development of the times, the technology, methods and means of cultural heritage protection of the Dunhuang Academy have been continuously upgraded and improved, forming a comprehensive scientific protection system. According to statistics, the experience summarized from the practice of Dunhuang conservation has been applied to more than 300 national key cultural relics protection projects, and has provided technical support and Chinese solutions for the protection of cultural heritage in Central Asia, Southeast Asia and other countries that jointly build the "Belt and Road".
Building a digital Dunhuang
Realize "cultural relics in the cave and look outside the cave"
As the screen lit up, the dome movie "Dream Buddha Palace" was staged wonderfully, and the seven classic caves of Mogao Grottoes with great artistic value appeared in front of the audience in turn, with exquisite murals close at hand, and statues of different shapes seemed to be within reach, and in the 20-minute viewing time, the audience was amazed again and again.
In 2014, the Dunhuang Academy built and put into use the Mogao Grottoes Digital Exhibition Center, and produced two digital films, "Millennium Mogao" and "Dream Buddha Palace", through digital Dunhuang resources. In 10 years, the number of moviegoers here has exceeded 14 million, which not only brings a new experience to tourists, but also relieves the pressure on the cave protection caused by the surge in tourists.
As early as the end of the 80s of the 20th century, Fan Jinshi, then executive vice president of the Dunhuang Academy, put forward the concept of "digital Dunhuang" in a forward-looking manner, hoping to use digital technology to make the cultural relics in the Mogao Grottoes permanently preserved and sustainably used. In 2006, the Dunhuang Academy set up a digital center specializing in the digital protection of cultural relics, and cooperated with universities, research institutes and related enterprises to tackle key problems.
"Digital collection is to generate digital images of caves, murals, painted sculptures and cultural relics related to Dunhuang through high-precision photography and video." Yu Tianxiu, director of the Institute of Digitization of Cultural Relics at the Dunhuang Academy, said that the work sounds simple, but if you want to reproduce the original Dunhuang cultural relics into the computer, the process is extremely complicated.
"First of all, it is necessary to comprehensively consider the size, shape, damage and difficulty of photography, design a complete and thorough digital photography acquisition scheme, and scientifically demonstrate the scheme. Then shoot with professional equipment such as custom tracks, camera cars, etc. Walking into Cave 341, the staff is collecting images on the north wall of the main room, Yu Tianxiu introduced that when shooting, a constant temperature cold light source must be used to ensure that the human impact is minimized, during which the color and clarity of the image are also strictly controlled.
"The collection work is not only boring, but also a test of patience." An Huili, who has been engaged in digital collection and splicing work for more than 10 years, said that assembling instruments and laying tracks in a small cave is quite like "making a dojo in a snail shell". If something goes wrong in one link, there will be problems in each link, and you can't be sloppy. ”
In 2020, the Institute of Digitization of Cultural Relics of Dunhuang Academy applied for and approved the entire cave digital protection project of Cave 130 of Mogao Grottoes. "The 130th total height is 28.2 meters, the mural area is more than 1,500 square meters, and there is a 26-meter-high Buddha statue in the cave, which is not only large, but also has a high curvature of the wall. Yu Tianxiu said.
Completing the collection is only the first step. "Since each photo is a partial image, we have to stitch it together to show the complete mural." An Huili said that this is similar to a jigsaw puzzle, which requires manual staring at the screen and correcting it little by little, "The error of the splicing needs to be controlled between millimeters, even the root hair of the character, and it must also be 'seamless'." ”
If the ancient craftsmen and painters painstakingly opened caves to paint and leave Dunhuang murals for the world, then today's Dunhuang Academy digital team uses technology to archive history. "To complete this work, it takes a lot of manpower and material resources. In the beginning, I could only shoot 2 or 3 caves a year. Yu Tianxiu said that with the maturity of technology, more than 20 caves can now be photographed a year and more than 100,000 pictures can be stitched.
Digitizing painted sculptures and murals, the Dunhuang Academy is a pioneer in China. From the beginning of the lack of ready-made experience reference, to the later through practical exploration to form a methodology, now, the Dunhuang Academy has summarized and formulated a set of work specification processes, forming 13 standards for collection, processing, storage, etc., which have been fully affirmed by the superior departments.
"After digitization, the Mogao Grottoes will not only allow more people to easily appreciate the charm of grotto art, but also preserve it forever." Yu Tianxiu said. Up to now, the digital conservation team of the Dunhuang Academy has completed the digital collection of murals in 295 caves and the image stitching processing of 186 caves. Completed the 3D reconstruction of 7 large ruins, 45 painted sculptures, and 3D laser scanning of the spatial structure of 212 caves.
At present, more than 20 million people have logged in to the "Digital Dunhuang" resource library platform to browse ultra-high-definition resolution images, and launched a 720-degree panoramic roaming of 30 caves. In addition, by clicking on the "Digital Dunhuang · Open Material Library", you can also carry out secondary creation, and upload the material library again after approval to become a new digital resource.
Strengthen academic research
Spread the splendid Chinese culture
Swing your waist lightly, draw a graceful arc with your arms, dance smartly, and look cute. At the end of September, at the "Model" and "Highland" Achievement Exhibition of Dunhuang Academy, the official virtual person "Jia Yao" of Dunhuang Mogao Grottoes was particularly eye-catching. This virtual animation image carefully created by the Dunhuang Academy can lead domestic and foreign audiences to experience and understand Dunhuang culture through various forms such as cave mural explanations, virtual live broadcasts of exhibitions, and dance performances.
On its side, more than 100 academic monographs, such as "Dunhuang Art Dictionary", "Gansu Tibetan Dunhuang Documents" (1-12 volumes), "100 volumes" "Dunhuang Grottoes Complete Works", "Archaeological Report of Mogao Grottoes No. 256, 257 and 259", etc., pave the way of "inheritance and promotion of academic research on cultural relics protection" in the new era. After 80 years of development, the Dunhuang Academy has become an important base for international Dunhuang studies, changing the past situation of "Dunhuang in China, Dunhuang studies abroad".
In 1900, after the north wall of the 16th cave of Mogao Grottoes in Dunhuang, the area of only 7.8 square meters of Tibetan scripture cave was shocked, and more than 70,000 pieces of ancient documents and works of art were shocked, which was called "Dunhuang Testament" by the academic circles, which gave birth to an international study - "Dunhuang Studies". However, due to historical reasons, they are scattered in many countries around the world.
"For researchers, it is particularly important to digitally restore scattered documents due to the age of the Dunhuang testament, the fragile condition of the paper, and the strict restrictions on the number of times they can be read." Zhao Xiaoxing, director of the Dunhuang Literature Research Institute of the Dunhuang Academy, said that the institute took the lead in compiling the "Implementation Plan for the Digital Restoration of Dunhuang Cultural Relics Lost Overseas", and signed cooperation agreements with collection institutions in United Kingdom, France, Hungary and other countries to promote the digital sharing and return of Dunhuang cultural and artistic resources.
After unremitting efforts, in 2022, the "Dunhuang Testament Database" was officially launched, providing high-quality academic resources and services for researchers of Dunhuang studies around the world. In recent years, the Dunhuang Academy has successfully applied for more than 60 national, provincial and ministerial projects, such as "Collation and Research of Historical Materials on Sino-Foreign Relations in Dunhuang" and "Research on the Interpretation of Dunhuang Grottoes Literature and Mutual Evidence of Pictures and Texts". The journal "Dunhuang Studies" won the 5th "China Publishing Government Award (Journal Award)".
In recent years, the Dunhuang Academy has adhered to the principle of "going out", deeply excavated and displayed Dunhuang art and its research results, held more than 10 "Dunhuang Culture Global Connection Activities", held the "Silk Road Pearl · Digital Eternity" Dunhuang Exhibition in Tel Aviv, Israel, and held the "Dunhuang No Longer Far Away - Approaching Morocco" Digital Dunhuang Exhibition in Rabat, Morocco, A series of international cultural exchange exhibitions were carried out simultaneously in the form of online and offline, telling the story of Dunhuang and spreading the voice of China in a form that people like to see.
"Dunhuang belongs to China, and Dunhuang studies belong to the world." Zhao Shengliang, Secretary of the Party Committee of the Dunhuang Academy, said that the connotation of Dunhuang Studies is incomparably broad and the content is incomparably rich. The Dunhuang Academy will always adhere to the protection of cultural heritage as the foundation, take academic research as the core task of career development, constantly improve the academic research system and discipline system construction of Dunhuang Studies, continue to lead the development direction of Dunhuang studies, interpret the value of Dunhuang culture from multiple angles and dimensions, and preserve, inherit and utilize the precious cultural imprint left by Dunhuang to mankind.