This work is partly supported by the Fundamental Research Funds for the Central Universities (No. 15CX06017A), National Natural Science Foundation of China (No. 61379106), the Young Scientists Fund of the National Natural Science Foundation of China (No. 61502153), Natural Science Foundation of Hunan Province of China (No. 2016JJ3031), the Shandong Provincial Natural Science Foundation (No. ZR2013FM036), the Scholarship from China Scholarship Council (No. 201506450033) and the open fund project of Hunan Provincial Key Laboratory for Technology and Application of Cultural Heritage Digitalization. The authors would like to thank the anonymous reviewers and editors for their insightful comments and valuable suggestions which have led to substantial improvements of the paper.