10.0 Acknowledgments
Funded by Sichuan and Chongqing Grottoes protection demonstration project (Dazu Rock Carving Niche of Sakyamuni Entering Nirvana and Small Fowan statues conservation and restoration project) undertaken by the Chinese Academy of Cultural Heritage, as well as by the basic scientific research service fee of the Chinese Academy of Cultural Heritage (2016-JBKY-06).
11.0 Data Availability Statement The data that support the findings of this study are available from the corresponding author upon reasonable request.