A number of cultural relics based on equal-scale high-fidelity digital 3D printing are on display in the National Museum.On the left is the"Purple Bamboo Avalokitesvara"statue of Pilu Cave in Anyue Grottoes,and on the right is the statue of Butag Maitreya and the 18 Arhats on the south bank of Lengquan Stream in Feilai Peak,West Lake,Hangzhou.These exhibits make visitors feel as if they are in the original space.
Located in Daxing Campus of Beijing University of Architecture,the statue of"18 movable Yungang Grottoes"is a demonstration practice of cultural heritage value based on the technology of"equal scale reproduction of large grottoes based on high-precision three-dimensional models".
By referring to the literature and analyzing the methods and contents of grotto carving,the scientific research team focused on the semi-relief areas such as Buddha,Bodhisattva and Arhat figure;At the same time,according to the level of detail,the hand of Buddha,the change of cassock texture,and the complex shape decorations are also the key points of printing details.
On February 13,after the rain and snow in the capital,the reporter went to Daxing Campus of Beijing University of Architecture and Architecture to find the statue of the 18th Cave of Yungang Grottoes made by the technology of"equal scale reproduction of large grottoes based on high-precision three-dimensional models".The 18th Cave is the famous"Tanyao Five Grottoes",which is of large scale,complex technology and high artistic value among the existing 252 caves.The 1∶1 reproduction of the statue,17 meters high and 22 meters wide,is the world's first large-scale reproduction project that can be assembled with 3D printing.It not only shows the original appearance of the cultural relics,but also has the functions of moisture resistance,flame resistance,corrosion prevention and waterproof,which can meet the requirements of lightweight,durable,convenient disassembly and long-distance transportation.We call it"the 18 Cave of Yungang on the move".
New interpretation practice
As early as 2005,Beijing University of Architecture and Yungang Grottoes Research Institute used 3D laser scanning technology to generate a complete point cloud and orthophoto image of the exterior elevation of Yungang Grottoes.The subsequent work of data collection,processing,storage and display has continued until now.
I arrived specially in the afternoon,expecting to see the beautiful moment when the soft warm light"carved"the statue again at sunset.Under the blue sky,the gods are graceful and lifelike;The beautiful and grand scene made people feel really shocked,and a desire to stretch out their arms and hope to gently fit with the statue arose spontaneously.
It took six years to complete the"Mobile Yungang 18 Grottoes".The teachers and students of Beijing University of Architecture have regarded it as an integral part of the campus landscape.The students described that the most beautiful moment is the morning:"The light of the morning shines on the statue from the side.This large campus sculpture exudes a sense of beauty that transcends history.At this time,there is not only the excitement brought by the singing of birds and the fragrance of flowers,but also the tranquility and firmness of the eyes of the Buddha,and the story and imagination displayed in the historical time.At this moment,there will be full of expectations to explore the future."
If compared with the original works of cultural relics,what are the differences and similarities?We call Ningbo researcher of Yungang Research Institute.He immediately took the scene photos of the 18th Cave.Ningbo is the director of the Digital Protection Center of Yungang Research Institute,and is responsible for the construction of"Digital Yungang",including the digital protection of Yungang Grottoes and related contents of smart scenic spots.By comparison,we can immediately see the uniqueness of the"moving Yungang 18 Grottoes"-the real space of the 18th Grottoes is relatively small,so Ningbo can only take a panoramic view of the main Buddha images with a wide-angle lens.The printed grotto statues provide a broad view of interpretation and observation.This is because when printing,scientific researchers have carefully studied and judged,omitted part of the grotto structure that blocks the whole picture of the statue,and showed the details of many statues from all angles to people as much as possible.
In 1987,"Mogao Grottoes"became a world heritage;Subsequently,"Dazu Stone Carvings"in 1999,"Longmen Grottoes"in 2000 and"Yungang Grottoes"in 2001 were listed in the World Heritage List.Without exception,these grotto cultural heritages located in China all meet the important(i)value standard of world heritage:they are the"peak","outstanding performance","masterpiece"and"treasure house"of human creativity and wisdom.No words or pictures,even huge artistic creation,can perfectly replace the feeling of the original site and objects when viewing the statues.However,the"moving Yungang 18 Grottoes",with another grand scene,urges people to feel the value of item(i)more accurately;The selection based on accurate data describes the most wonderful and unforgettable details,skills and proud achievements of the original work.
From the perspective of the value of the World Heritage,it completely explains the 18th Cave.
How was it built?
In December 2021,the State Administration of Cultural Heritage issued the Special Plan for the Protection and Utilization of Grotto Monastery during the"Fourteenth Five-Year Plan".The basic principles put forward by it are:to insist on protection first,to insist on inheriting and carrying forward,to strengthen the historical information of the grotto temple,to insist on scientific and technological support,to insist on adjusting measures to local conditions and implementing policies according to classification,which are almost closely related to the large-scale utilization of scientific research and new technologies.At the same time,the rapid development of digitalization,informatization and intellectualization has created new ways for the protection and inheritance of cultural relics and cultural heritage,and provided technical support to realize the vision.
The"Mobile Yungang 18 Grottoes"weighs about 40 tons,and needs to face many cutting-edge challenges such as large volume,high difficulty,and multidisciplinary intersection.How was it built?Li Aiqun,Vice President of Beijing University of Architecture and Architecture,is the team leader of this large-scale grottoes and other scale high-precision modular replication project.According to him,with the research goal of equal scale and high fidelity reproduction,the scientific research team has gathered many disciplines such as architectural history,architectural art,surveying and mapping,materials,structure,modern manufacturing,monitoring and monitoring.When 3D printing technology is used to restore the various parts of the Buddha,in order to ensure the authenticity and integrity requirements,the key parts must be consistent with the original Buddha image,so scientific and technological workers have carried out decomposition printing."The average size of each piece is about 40 cm,a total of 2790 pieces."said Xu Donghui,senior experimenter at the Engineering Practice Innovation Center of Beijing University of Architecture,"Each piece is printed layer by layer-not as fast as people think.Each piece needs to be printed for more than 20 hours."At the busiest time,a total of 50 printers were started at the same time,which took about a month and a half.Then,nearly 3000 small pieces were assembled into more than 120 models,and finally assembled into a whole.
Zhu Lei from the Civil Engineering College is responsible for the drawing and construction of the overall skeleton.He said that the skeleton customized according to the outline of the printed copy can be disassembled repeatedly,and the technical problems such as earthquake resistance and wind protection have been taken into consideration,so that it can withstand the Richter 9 earthquake.
The scientific research team took the lead at home and abroad in proposing the"5+1"key technology of high-fidelity equal proportion replication for large-scale cultural heritage,namely,high-precision three-dimensional information retention technology,art value skin partition technology,high-performance composite material research and development technology,assembly-type structure design research and development technology,multi-dimensional digital rapid prototyping and manufacturing technology,and replication whole-process safety monitoring technology.At the same time,the team took the lead in achieving a series of innovative achievements in the precise collection and processing of grotto data,the preparation and connection of prefabricated modules,high-performance replication materials,high-precision 3D printing and splicing,and the controllable and adjustable overall model.
Diversified 3D printing presentation
Two days after leaving the"Moving Yungang Eighteen Grottoes",I came to the National Museum again to see the bustling"Exhibition of the Achievements of Chinese Painting Series".I bypassed the calligraphy,painting,flowers and birds and authentic calligraphy left by the ancients and went directly to see a small unit.Contemporary people have used the latest technology to display the new results of proportional printing of statues and paintings in the grottoes.There are not only caves and statues from Yungang and Dunhuang,but also vivid and lifelike"Purple Bamboo Avalokitesvara"statue of Pilu Cave in Anyue Grottoes,and Bubao Maitreya and the Eighteen Arhats on the south bank of Lengquan Stream,Feilai Peak,West Lake,Hangzhou.Among them,the"Purple Bamboo Guanyin",which is based on the digital 3D printing and reproduction of the same scale and high fidelity,is half-folded and sitting on its back,leaning against the embossed purple bamboo and willow net bottles,and wearing a hollow corolla on its head;The dress is elegant and dynamic.The statues of Maitreya and the Eighteen Arhats,completed in the Southern Song Dynasty,are lifelike and have a cordial feeling from the altar to the people.
These exhibits and the"Mobile Yungang Eighteen Grottoes"show different technical application directions:one is for outdoor use,and the other is for indoor use;One group is more magnificent,while the other group is more colorful and exquisite.Hou Miaolo,professor of the School of Surveying,Mapping and Urban Spatial Information of Beijing University of Architecture,is mainly engaged in the research of digital protection of cultural heritage,and has also deeply participated in the scientific research of the statues of the Eighteen Grottoes.Another goal that we often think of during the construction process is"movable".The final results should meet the requirements of disassembly,adjustment,corrosion prevention,durability and repeated display."For the reproduction of large grottoes,processing cost,processing cycle,weight and durability are all important factors to consider,"Hou Miaolo said.The scientific research team designed a block assembly structure for the"18 mobile Yungang Grottoes",divided the overall grotto model into several sub-models,and printed them out separately.
On the surface,these methods are simple and easy to implement,but they will encounter multiple constraints in actual production.First of all,the size of the segmented model should meet the requirements of convenient production and easy assembly and disassembly;Secondly,the mechanical structure and shape of the shell should be considered during the segmentation;The segmented model must meet the accuracy of no damage,overlap and missing,and the placement angle must meet the printing requirements.In addition,in order to make the statue withstand the long-term test of the outdoor environment,it is necessary to improve its weather resistance,water resistance and other performance,while also controlling its weight.
There is still a long way to go
What is the meaning of replication?
In recent years,in addition to the three values of traditional cultural relics"science and technology,history and art",people have increased their attention to"social value"and"cultural value"from the perspective of cultural heritage.The cultural power provided by cultural relics and cultural heritage for social development has far exceeded the impact of industry and scientific research.The reporter himself experienced the feeling brought by the"18 Cave of Yungang",and also stood at the exhibition site of the National Museum,observing the time and expression of people's stay,and paying attention to the dialogue between children and their parents.It can be clearly felt that these scenes and works copied in equal proportion also have the unique expressiveness and influence of the grotto temple;We can also realize that these attempts and efforts have a very broad space for development.
The"18 mobile Yungang Grottoes"has stood for four years.When I went to see it,it was not its best time.Some materials showed signs of damage.After a brief depression,we found that this put forward new requirements for the next step of scientific research.
"3D printing of the World Cultural Heritage is a worldwide research hotspot,and many scientists around the world are doing this.The'Mobile Yungang Eighteen Grottoes'have accumulated experience in terms of interdisciplinary breadth,huge volume,continuous improvement of materials,relocation and post-monitoring and evaluation,and have had more in-depth thinking and research planning on classification technology and integration technology,"said Professor Hou Miaolo,"Through further exploration,new achievements that can be used for reference at home and abroad can be systematically formed in many aspects."
The Special Plan for the Protection and Utilization of Grottoes during the"Fourteenth Five-Year Plan"launched the"Digital Grottoes"project:to formulate standards and specifications for data collection,processing,storage and management of grottoes.We will promote the digital collection and exhibition of murals,colored sculptures,statues,statues,stone carvings,and overseas Chinese grotto temple cultural relics and Dunhuang documents,and establish a long-term mechanism for digital resource sharing and management.The"Mobile Yungang 18 Grottoes"can only be seen as a small node in the overall national planning.More achievements require more people and more scientific research teams to continue to pay
"What are you mainly doing?"The reporter asked in passing when he asked Ningbo of Yungang Research Institute for on-site photos.
"Digital protection of cultural relics,including data collection,processing and storage."Ningbo replied simply and clearly.
"How long have you been working?"
"18 years."
"How much longer?"
"Yungang has been digitizing for nearly 20 years.It is estimated that in another 10 years,all data collection will be completed!"
Extended reading
Located in the east of the west area of Yungang Grottoes Group,Tanyao Five Grottoes,numbered from the 16th to the 20th,are the first five royal grottoes dug in the Northern Wei Dynasty.These are the five caves that were uniformly planned and built in the Northern Wei Dynasty.The 18th Cave is among the"Five Grottoes",commonly known in the Qing Dynasty as the"Lisan Buddha Cave"or the"Ahu Buddha Cave".
The statue of Buddha in the center of the north wall is about 15.5 meters high,wearing a thousand Buddha cassocks,and is dignified.The statue of the Lord stands tall and majestic,with a dome on the top of his head and a lotus platform on his feet.The left hand holds the"vestment"and bends the elbow to touch the chest.There is a"web"between the fingers.The right lower arm is broken and lost.The Buddha is wearing a cassock with the right shoulder bare.It has a strong texture and occasionally has traces of color painting.