Yungang Grottoes debut 3D printed cave replica

With 3D printing and high-fidelity digital technologies, the immovable Yungang Grottoes and their 1,500-year-old masterpieces of Chinese Buddhist art took the first steps into a wider world.

The world's first mobile 3D-printed 1:1 replica cave of the Yungang Grottoes made its debut on June 12 at the Museum of Art and Archaeology in East China's Zhejiang province. It was open to global visitors both offline and online.

"Entering the replica cave is like being in cave No 12 of the Yungang Grottoes that stands more than 1,500 kilometers away from here," says Lu Jiwen, deputy director of the Yungang Grottoes Research Institute.

Cave No 12, also known as the Music Cave, was carved in the fifth century, with richly detailed sculptures of heavenly figures and musical instruments from home and abroad. These figures represented the earliest royal symphony orchestra in ancient China and played a vital role in the history of Chinese music and dance.

The Music Cave is 14 meters deep, 11 meters wide and 9 meters high. The replica accurately reproduces its shape, exquisite statues and the subtle traces of erosion brought by thousands of years of weathering to the grottoes.

The Yungang Grottoes, located in the northern Chinese city of Datong, Shanxi province, has 45 major caves and more than 59,000 stone statues. With a grotto complex stretching about 1 km from east to west, it is one of the largest ancient grottoes in the country.

Since August 2016, the Cultural Heritage Research Institute of Zhejiang University has cooperated with the Yungang Grottoes Research Institute to collect high-fidelity 3D digital data of cave No 12.

Diao Changyu, deputy dean of the cultural heritage research institute, says the joint project team has overcome technical difficulties such as data collection and processing, structural design, block printing and coloring for the replica.

"The statues were skillfully carved," says Diao. "In the digital acquisition and printing process of cave No 12, the project team encountered new challenges and reached the 'ceiling' of existing technologies.

"The digital collection accuracy of the cave reached 0.03 mm and the final reproduction error of the cave is less than 2 mm," says Diao. "The colors were also replicated with a more than 95 percent accuracy."

In order to give the replica a more realistic texture, the art team of the Yungang Grottoes used mineral pigments in line with ancient methods to color the replica grottoes over an area of about 900 square meters, which took about eight months.

"If you touch the wall of the replica cave, you can even feel the texture of sandstone and limestone," says Diao.

The Music Cave reproduction was assembled with 110 two-meter-long building blocks.

"It takes one week to complete the assembly of the bricks," says Ning. "The huge grottoes are no longer immovable and people across the globe will have the chance to take a closer look at the delicate masterpieces."

After the exhibition in Hangzhou, capital of Zhejiang, the replica of the Music Cave will start a global tour.