Stone Carvings Get New Archives
Translated by Dai Wei Edited by Mark Zuiderveld Photos by Li Xiaoyin and courtesy of Fangshan Cultural Relics Protection Institute
Since 2016, Fangshan District has accessed high- precision 3D scanning to establish digital archives of stone carvings to protect for relics and repairs.
Beijing Municipality has a vast accumulation of cultural items and relics spread far and wide, in many categories, which are valuable and date back as far as 3,000 years.
Still surprising to visitors, relics are currently held in its museums, which await similar items to be excavated and protected. Organisations and archaeologists in Beijing still try to find them and add them to the archives.
One of these is the Fangshan Cultural Relics Protection Institute, which has conducted research on 25 towns and 95 villages, and come up with 380 stone carving sites in Fangshan District since 2016, with the support of the Fangshan District Cultural Committee. It has access to high-precision 3D scanning technology to establish digital archives of these carvings. It also protect relics and makes repairs if necessary.
The district’s many ancient stone carvings, dating back to the Sui (581–618), Tang (618–907), Ming (1368–1644) and Qing (1644–1911) dynasties, are examples of its past.
These items aren't documented in history books or records, only revealed by inscriptions on tablets, of which there are numerous examples, such as some stone tablets in the Huguo Xiangguang Temple, previously part of a villa of Yao Guangxiao (1335–1418), a high-ranking official and advisor to Emperor Chengzu (1402–1424) who took power during the Ming Dynasty.
The Chici xiangguangsi beiji (“imperial records of tablets of Xiangguang Temple”) indicates that “Yao Guangxiao was a meritorious
official with a high rank. He gave up the position, and went back to the Huayan Temple in Taihu to live in seclusion. The emperor granted him Xiangguangyuan (Luminary Garden) as a villa.”
However, Yao's biography as recorded in the Mingshi (“history of Ming”) says that Yao lived in the Qingshou Temple in Beijing and doesn't mention him going to the Huayan Temple or Xiangguangyuan Villa as an imperial gift. From this we can conclude that the records of the Xiangguang Temple fill a void in official history.
Yao was closely connected with Fangshan. He visited the Yunju Temple and Shijing Mountain in Fangshan in the first lunar month of 1388. That same year, he engraved an impromptu poem titled “Shijing Mountain” on the stone walls of the mountain's Leiyin Cave.
When Emperor Chengzu was in power, Yao was living in seclusion in Huayan Temple, Fangshan, and the emperor granted him to use Xiangguang Temple as a villa, so it became Xiangguangyuan, or the more common Shaoshiyuan.
The Huguo Xiangguang Temple is now in Dahanji Village at the foot of Longgu Mountain, in Fangshan District. The only structures that remain include Shanmen (Mountain Gate) Hall, Zhonggu (Bell and Drum) Tower, and Tianwang (Heavenly King), Mahavira Guanyin), a Merciful Buddha, and Ksitigarbha halls. There is a large vacant field behind the Mahavira Hall with dilapidated halls.
Other inscriptions note, “The renovated Xiangguang Temple has several halls. If you enter the mountain gate at the front of the temple, you see the first hall, Tianwang, with a statue of a Buddhist warrior attendant, across the first hall, you enter Mahavira Hall with a statue of the Rulai Buddha ( Tathagata). You then enter the Fangzhang Hall where the abbot lives, then enter the Dabei Pavilion, with a statue of the Dabei (Great Compassion) Buddha. You then enter a square with buildings around it and you can see the renovated Baoji Tower (Duobaofo Tower) to the east of the temple. There is a 5.2-hectare space for burning incense added after the Xiangguang Temple was built. That year, the Xiangguang Temple, Yunju Temple, and several other temples on Shangfang Mountain were all large temples in Fangshan. The Xiangguang Temple was preeminent for a period of time after Emperor Shenzong (1573–1620) ordered it repaired.”
The temple's present abbot says he isn't clear about past events and only knows that Huguo Xiangguang Temple was once a grand temple with five major halls and often visited by pilgrims, currently far from being that prosperous today.
Nonetheless, thanks to inscriptions and other bits of history and word of mouth, people have come to know more about its history and would think it sad if these traces of history were erased. The inscriptions need to be collected with a digital archive for the stone carvings.
In front of the Mahavira Hall, there is a temple with two 4.8-metre-tall stone tablets, each with a square base. According to Jin Chao, Director of the Fangshan Cultural Relics Institute, these two stone tablets were erected during Emperor Shenzong's reign in the Ming Dynasty.
At the top of one temple to the east are descriptions of its history, layout and renovation. This information is priceless for research purposes. Archiving and protecting the temple's tablets could be a major reason for Fangshan to begin work on a digital file for errant stone carvings.
Making the Virtual Real
To begin archival work, scaffoldings were put up around the site. A staff member dusted off the top of the two tablets with a brush, then stuck on laser positioning stickers. Other workers got busy arranging laser scanners, computers and other electronics and did a 3D-scan and digital sampling for the two tablets. Jin explained the special nature of the tablet inscriptions and their role in traditional culture for the historical, literary, and artistic value for both China's and Beijing's history.
Unfortunately, valuable tablet inscriptions have been worn down by wind and rain over a long period, with some so seriously damaged that the inscriptions are hard to read.
The old ink rubbings used to preserve inscriptions actually do more damage when the ink seeps into the stone. The use of a rubbed art paper would easily have pulverised their surface, causing it to crumble apart. These factors caused researchers to go looking for new technology and methods to document the content of the stone tablets.
In response, the committee asked New Dimensional Imagination Digital Technology (Beijing) in 2016 to do some high-precision 3D scanning work for 380 stone relics. As a result, their historic and artistic value has been completely preserved. The database functions cover archival management, analysing defects, dimensional displays and other areas to ensure their cultural preservation. Data collection is coming to an end.
“The laser positioning points provide certain coordinates,” explains Wang Heyu, part
of the company in charge of fieldwork. Wang goes on to explain that, before they use this laser point sticker method, the technicians had to work on the scaffolding for a long time by cleaning away dust. Now, with laser positioning points, they're ready to start digital scanning.
Wang also notes, “With the traditional rubbing method, you only get a rubbing from the tablet inscription and it's not that satisfactory. But, with the digital rubbing method based on 3D scanning, you can scan the inscription in depth and retain the texture of the tablet. In post-production work, all information on the relics is reproduced in 3D and, even if the characters are not clear, they can be brought out through deep scanning, reproducing the tablet patterns.”
The scanned data is then sent back to the computer so that digital samples similar to traditional rubbing appear on the screen, but with other details, such as ornamentation and patterns in a clear appearance, with details that the naked eye couldn't normally discern.
Because the scanning only functions as a data collector, other patterns caused by tablet breakage need symmetric technology restoration in the post-production stage, while unrecognisable characters need digital repair of the prototype based on the opinions of specialists, scholars and research.
The data resolution can reach 0.05mm, with an accuracy of 0.03 mm and dot pitch of 0.4 mm-0.2 mm and images with high resolution of up to 7 billion pixels can be obtained via integral and local image collection of plane 2D cultural relics (such as a mural) and curved-surface 3D relics (stone carving). Colours can be accurately restored, and details in texture, colour and ornamentation can be revealed more accurately.
The data is sent back to the company's digital repair centre for post-production work and will later yield line graphs, 3D diagrams with precious stone inscriptions to reappear in digital form. A giant database can provide stone inscriptions with its own digital file, with data support for relics protection, restoration, research and exhibitions.
Scaffolding for 3D Scanning
Extracting that data wasn't without hard labour. The process of erecting the scaffolding, wiping the dust from the stone surfaces, putting on the laser positioning stickers, conducting highprecision 3D scanning, data verification and return took five workers nearly two days.
Ensuring that the collected data is precise, the scanning consumes a lot of time and, since it uses infrared rays, this can be greatly affected by sunshine. Extra care has to be taken to keep the sunshine away.
According to Jin, digital archive work is separated into three phases: the first being scanning formulation, or to be more specific, doing the fieldwork on preserving stone carvings at the early stage and defining scanning methods; the second is field sampling by arranging mechanical methods to create a scanning environment for high-precision 3D digital scanning for stone inscriptions with the aim of securing the relics and preserving the environment from damage, in accordance with scanning methods; and the last is to establish a database management system, assuring that the mass data analysis by field sampling, drafting, colour restoration and data entry is conducted to establish a digital archives of the stone relics.
Those objects that the staff arranged for the digital archives included not only stone tablets, but also Buddha figures and rock paintings. They had to travel to 25 towns and 95 villages in the district and pore over 300 relics.
These places included Yao Guangxiao's tomb, a stone Tripitaka in the Yunju Temple, an epitaph of the provincial governor, Liu Ji (757–810) of the Tang Dynasty, Lianquanchan Temple, and rock paintings on the Beizhihe near Xiayun Mountain.
During all this activity, they were sometimes mistaken for thieves and were harassed by locals. In one instance, they weren't released from local custody until the Fangshan Cultural Relics Protection Institute explained the situation to the locals. This shows how active the masses are in protecting relics.
During fieldwork, the institute made some preliminary measurements and attained geological records, discovered some distant stone carvings that weren't on their list and able to document them. It also estimated the work of on-site scanning, and taking photos.
Xu Chao, the project's executive director, said that what impressed him most was the “Hongluosanxian” experience, where the mountain seemed to spiral upward, and had three tiers of cliffs with winding mountain paths under each of them.
What Xu said he needed were ruins such as ancient temples, tablets and towers that decorated these cliffs and were a source of data. The mountain pathways were so rugged that a person might have to walk for two or three hours to get to the area, so staff members collecting data couldn't carry too much equipment.
Even the scaffolding they carried had to be light, which made scanning all the more difficult. They also needed an electric generator to supply power on the mountain, which added more weight.
Xu expressed it most succinctly, saying he wouldn't ever want to make that trip to “Hongluosanxian” a second time. He was there three times in all, including early exploration. For the data collection on “Hongluosanxian,” he and the team spent more than six hours every day coming and going, and they could only scan for around two hours each time.
It's hard to imagine that there were stone-carved relics with a long history hidden among these high mountains and lofty cliffs still in existence if it weren't for the hard work of these intrepid staff members.
Digital Archive Protection
One other thing the staff members had to do was to establish digital archives for some indoor stone-carved relics, such as the Tripitaka in Yunju Temple. One of these was when they unearthed the tomb of Liu Ji from the Tang Dynasty.
When that happened, on June 22, 2013, many in Beijing stayed home instead of going out, with their eyes glued to a live BTV morning show of an on-site excavation.
Liu was the provincial governor of Youzhou, a major secretary, and an imperial commander-in-chief, a distinguished figure. The age of his tomb was apparent as it was huge. Its structure reflected typical features of Tang tombs in the Central Plains but was crucial for research on the military governing system and Beijing's tombs during the late Tang.
Among the recovered funerary objects, a large epitaph with painted relief of the twelve Chinese zodiac figures intended for Liu's wife, Zhang, drew the most attention from specialists and scholars. This was a rare item from the Tang epitaphs discovered around that time.
The epitaph cover of Liu's wife also had a large, gold coloured painting, and was decorated with the incised gilt seal characters reading, “Epitaph granted by Tang's late Madam of Ji to madam of Yan, Qinghe imperial madam.”
There was also an embossed image of civil officials holding the twelve figures of the Chinese zodiac and coloured peony patterns painted with evenly distributed colours. This epitaph for Liu's wife was once put on display at a 2015 exhibition on the common history of Beijing, Tianjin and Hebei.
The beauty of this over-1,000-year old epitaph is hard to appreciate even if looked at closely. But, today, thanks to the precision of 3D scanning and digital recovery, people can admire and learn more about this relic from digital archives, and come to appreciate every single detail.
As of July 31, 2017, this archiving of the stone carvings carried out by the institute had come to an end but leaves behind a good example of relics protection in Beijing today and how people can use science and technology to collect data for digital archives to better protect stone relics and retain their artistic value.
This archival preservation of stone carvings is like providing “digital insurance” for relics and a way to resist the ravages of time to prevent a vanishing culture. Digitisation has become a new means of revealing history, and of how relics living in this digital sea can regain their original glory.
A high-precision 3D scan of a stone carving
Scaffoldings help to keep 3D scanning in place for a high stone tablet.
Left is a detail from a stone carving, and right is the high-precision 3D scan.