For those who can's visit, grottoes come to them

Based on modern photographic techniques and remote sensing technology, Huang and others collected data on the cultural relics — mainly photos and sensing footage — and created a digital copy of Dunhuang online.

"Because the murals and Buddhas have angles, deformation could easily happen," he said. The sensing requires natural light, which means teams could only work in daytime.

That was in 2007, when Huang had just earned his doctoral degree. Later, the project went outside the caves.