Built in Kaitai 9 years after the beginning of the Liao Dynasty (1020 A.D.), the Daxiong Hall of Fengguo Temple (Yixian County, Liaoning Province) is one of China’s largest existing ancient single-eave wooden architecture structures. In 2012, it was listed on the “Preliminary List of World Cultural Heritage in China.” Preserved Buddhist murals depicting the Yuan Dynasty cover approximately 470 m2 of the hall’s four walls. Since the in-situ reinforcement and protection of the mural, conducted in the 1980s in cooperation with the maintenance and restoration project of the main hall, seriously developed cracks—known as secondary cracks—have become a primary factor affecting the mural’s structural stability. In this study, we conducted a comprehensive investigation using a full-frame digital camera, an industrial endoscope, an infrared thermal imager, an online environmental monitoring system, and a three-dimensional laser scanner. Our results, and other relevant materials, allowed us to deepen our understanding of the existing structural features, the nature of the cracks, the deformation conditions, and the environmental characteristics of the mural. Moreover, we provide a further discussion on the macroscopic formation process of the secondary cracks.

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Study on the Causes of Secondary Cracks of the Eave Wall Mural of Daxiong Hall at Fengguo Temple in Yixian, Liaoning, China

Abstract Many precious ancient murals are seriously deteriorated due to long-term environmental influences and man-made destructions. How to effectively protect ancient murals and restore these murals’ original appearance has become an urgent problem for field experts. Modern computer technology makes it possible to virtually restore the deteriorated areas in ancient murals. However, most existing mural restoration approaches require manual calibration of the deteriorated areas, which is very difficult and time-consuming. It has been noticed that the earth layer flaking and cracks are the most common problems of ancient temple murals. This paper proposes an automatic calibration method for the earth layer flaking and cracking deterioration of murals by taking temple murals from the Ming Dynasty in Zhilin Temple as the study object. First, we extract the texture and line features of the deteriorated murals by using multi-dimensional gradient detection in the HSV space. Then, a guided filter operation is employed to highlight the disease (deteriorated) areas and meanwhile suppress other unwanted areas, which helps to extract the flaked areas or cracked lines from the digital murals. The filtered images are segmented by using an automatic threshold to obtain the initial masks of the mural disease areas. Next, we use a two-dimensional tensor voting technique to connect the discontinuous edge curves of the extracted disease areas. Afterwards, the masks of flaking and cracking areas can be generated after morphological processing. Finally, we obtained the calibration results by adding the masks to the original digital murals. Experimental results show that our method can rapidly and accurately calibrate the cracks and the earth layer flaking diseases in the ancient murals. As compared to existing calibration approaches, our method can achieve better performance in subjective visual quality and objective evaluation metrics. Moreover, the method does not need human-computer interaction. This research work provides a solid foundation for the following virtual and practical restoration of ancient murals. 

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Automatic calibration of crack and flaking diseases in ancient temple murals

Abstract As non-renewable cultural heritages, murals have important implications in historical customs, religions, and philosophy as well as their aesthetic values. Recently, many murals are threatened by natural factors and human activities. During the past decades, there are increasing interest in the investigation of murals. Here we review the current status of murals and provide an up-to-date summary of achievements related to murals. The murals that draw the most attention are distributed in Mexico, Ireland, China, and Spain. The aesthetics, history, cultural, educational, and economic values of murals are comprehensively analyzed. The main research technologies used to detect the chemical compositions and physical structures of murals are also summarized. The restoration of murals includes several procedures such as stabilization, repair, surface cleaning, and pigment reconversion. Emerging technologies such as computer science benefit the research and conservation of murals. We also propose that tourism management and climate change should be incorporated into the conservation of murals in the future. 

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Current progress on murals: distribution, conservation and utilization

The main building of Fengguo Temple, located in Yixian, Liaoning, China, is one of the oldest wooden architecture structures, built in 1020. The inner walls of the building are decorated with Buddh...

Yuan He

Papers

Deterioration Caused by A New Support Layer Bonded with Epoxy Adhesive to the Mural Paintings at Fengguo Temple in Yixian, Liaoning, China

Study on the Causes of Secondary Cracks of the Eave Wall Mural of Daxiong Hall at Fengguo Temple in Yixian, Liaoning, China