The No 20 cave is representative of the Yungang Grottoes in Shanxi province. The Yungang Grottoes Research Institute is working on scanning all the caves for digital versions. (CHEN XIAODONG / FOR CHINA DAILY)

China's Yungang Grottoes will complete scanning of all its caves in five years, paving the way for the creation of digital versions that can withstand weathering and other real-world damage.

So far, the UNESCO World Heritage Site in Shanxi province has completed three-dimensional scans for one-third of its Buddhist grottoes, according to the Yungang Grottoes Research Institute.

Ning Bo, director of the institute's digitalization office, says they are racing against time. "Weathering is like cancer to grottoes, eating away at the sculptures year after year," Ning says.

As there is not a lot of technology available to prevent such progressive damage, preservation of existing information is now an urgent task.

Using three-dimensional laser scanning and multiplanar reconstruction, the institute is working to capture the shapes, colors and other fine details of the grottoes and create millimeter-level digital archives for future study and preservation.

"We hope to preserve the grottoes in digital form as much as possible, so people in the future will still have access to the information even after the grottoes erode with time," says Ning, adding that the digitalization will also allow the public to "visit" the grottoes more easily on their computer screens.

The digitalization project, which began in 2003 at the grottoes, still faces challenges posed by the enormous sizes of the caves, its complicated and exquisite structures.

"The Yungang Grottoes were built into a mountain, and so our team is actually scanning structures as huge as mountains. Besides, the inner structures vary wildly from exotic domes to traditional Chinese architecture, unlike flat murals (that can be more easily scanned)," Ning says.

Located in the city of Datong, the 1,500-year-old Yungang Grottoes have 45 major caves and more than 59,000 stone statues. With a grotto complex stretching about 1 kilometer from east to west, it is one of the largest ancient grottoes in the country.