“In Gaotai, we have a special team with select skilled personnel and are collaborating with surveying departments,“ says Xun Defei from the Gaotai county bureau of culture, sports, radio, television and tourism.

　　“We use fundamental data and land survey information, employing drone aerial surveys and Global Navigation Satellite System positioning devices for on-site investigations,“ he says.

　　The office work involves overlaying protection boundary data and construction control zone data onto imagery, and creating specialized maps. These outcomes support future site investigations and grotto protection work, he says.

　　With the concerted efforts of the local cultural heritage and natural resources departments, Zhangye has completed the “Two Lines Mapping “for national and provincial key cultural relics. The data has been integrated into the city's “One Map “system for land-use planning. The city aims to complete the mapping for all ungraded immovable cultural relics by the end of this year, Bian adds.