Dazu Rock Carvings Research Articles

Numerical analysis on crystallization inside porous sandstone induced by salt phase change

The behavior of water and salt inside porous sandstone is crucial for determining the durability of stone heritage. This involves multiphase coupled processes, yet previous analyses have paid insufficient attention to the spatial and temporal characterization of solution-crystal phase change. Based on the salt crystallization experiments, theoretical models and numerical computational frameworks are synthesized to simulate multiphase processes. Subsequently, equations are established for coupled water-salt-heat-mechanical interactions in the multiphase media. Then, the critical state of solution-crystal phase change is analyzed through the evolution of saturation, crystallization pressure, and porosity. The findings indicate rapid solution saturation growth at positions with minimal wetting front fluctuations, leading to initial crystallization. Further tracing reveals that crystallization evolves through discrete crystallization, annular crystallization, and crystallization expansion stages. By investigating the crystallization pressure and the crystal morphology, it is possible to quantify the dynamics of crystal pressure on constraint surfaces and solution pressure. In addition, the change in porosity can be observed by simulation of dry and wet cycles to obtain crystallization initiation. The numerical calculations agree well with the experimental results, providing valuable insights into the deterioration mechanism induced by salt crystallization in the porous sandstone of Dazu Rock Carvings.

A Novel Optimization Approach for Revolutionizing Architectural Design in Chinese Cultural Heritage

Chinese cultural heritage architecture, a blend of traditional and modern construction methods, showcases the country's technological, artistic, and cultural advancements, yet its preservation faces challenges due to structural decay and aesthetic degeneration. Using Microtrans Maryland 4-1000, Dazu Rock Carvings, Nanchan Temple and Foguang Temple smokescreen were captured; surface images and ground photos were captured with smokescreen resolution of 5192 x 4153 pixels. The goal of the research is to use an Ensemble Ant Colony Fused Convolutional Capsule Neural Network (EAC-CCNN) to enhance fault analysis in Chinese cultural heritage structures images, then the combination of Augmented Reality (AR), and Building Information Modeling (BIM) to enhance the designing model for the safety management and decision making. The process entails gathering and annotating a variety of information, creating a hybrid EAC-CCNN model to investigate the architectural building's problem, training it, integrating it with BIM, doing on-site inspections, and utilizing AR-enhanced BIM models to analyze the flaws found. The findings demonstrate how this integrated method improves the precision of flaw diagnosis, fosters teamwork, and aids in the upkeep and preservation of cultural heritage assets. Metrics including accuracy and F1 score are used to evaluate the machine learning model recognizes and categorizes flaws in Chinese cultural heritage architecture. The defect identifying and safety management model of architectural designing outcome of the accuracy is 93.29% and F1 Score is 95.47%. During the training, validation, and testing phases, performance is evaluated by project goals. With the help of this method, machine learning models can be trained to identify patterns, identify flaws, and generate well-informed predictions in a variety of circumstances.

Knowledge graph representation method for semantic 3D modeling of Chinese grottoes

The integration of 3D geometric models with semantic information significantly improves the applicability and comprehensibility of cultural heritage. The semantic 3D modeling of Chinese grottoes poses challenges for individuals without expertise in cultural heritage due to gaps in domain knowledge and discrepancies in understanding. However, the existing domain ontology and knowledge graph provide an insufficient representation of the knowledge of Chinese grottoes. To overcome these obstacles, we propose a knowledge graph representation method to provide explicit knowledge for participants at different stages of semantic 3D modeling of Chinese grottoes, which includes schema layer construction and data layer construction. On the schema layer, we design a domain ontology named ChgOnto (Chinese Grottoes Ontology) that consists of four high-level concept classes: spatial object, informational object, digital device, and temporal object. Among the classes in the ChgOnto, the components (e.g., cliff wall, cave roof, cliff wall footing), elements (e.g., primary Buddha statue, pedestal, decoration), the properties (e.g., length, width, depth) of caves and niches in Chinese grottoes as well as the spatial relationships between them are all precisely defined. ChgOnto also reuse the classes from the renowned CIDOC CRM ontology in the cultural heritage field and GeoSPARQL in the geospatial domain, facilitating integration between the two subjects. Considering the schema layer as the conceptual data model, the data layer extracts knowledge from unstructured text through natural language processing tools to instantiate the abstract classes and fill the properties of the schema layer. Finally, the knowledge required for semantic 3D modeling of Chinese grottoes is expressed in the data layer by a knowledge graph in a fixed expression form. Dazu Rock Carvings, a World Heritage site in China, is selected as a case study to validate the practicality and effectiveness of the proposed method. The results reveal that our method offers a robust knowledge-sharing platform for the semantic 3D modeling of Chinese grottoes and demonstrates excellent scalability. The method proposed in this paper can also serve as an informative reference for other types of cultural heritage.

Application of Ground-Penetrating Radar with the Logging Data Constraint in the Detection of Fractured Rock Mass in Dazu Rock Carvings, Chongqing, China

Geologic interpretation results from conventional ground-penetrating radar (GPR) detection methods tend to have a certain degree of uncertainty. In order to improve the reliability of ground-penetrating radars in the detection of rock mass fissures in grottoes, this study proposes a ground-penetrating radar detection method with the logging data constraint, which is applied to detect the fractured rock mass in the Baodingshan Scenic Area of Dazu Rock Carvings, Chongqing, China. First, conventional logging and borehole televiewer data were compared and verified, yielding detailed lithological and wellbore fissure information. Next, electromagnetic wave velocity was calibrated using GPR profile and the depth of the stratigraphic interface determined by borehole data. Utilizing this calibrated velocity, we are able to accurately calculate the depth values of anomalies in GPR interpretation profiles. Subsequently, we compared the preliminary GPR interpretation profile with the borehole televiewer images. After eliminating false anomalies caused by interference, we obtained more reliable location information for detection targets such as fissures, fracture zones, and weak interlayers. The results of fissure detection in the Dazu Rock Carvings indicate that the detection results of ground-penetrating radar are verified and supplemented under the constraints of stratigraphic and well-wall fissure information obtained by logging. This effectively mitigates the influence of multiplicity and false anomalies of GPR detection on interpretation results. GPR with the logging data constraint enhances the accuracy of the fissure detection results, providing novel technical means for the protection and restoration of grotto relics.

A hyperspectral evaluation approach for quantifying salt-induced weathering of sandstone

Salt-induced weathering is a common phenomenon in stone relics, and its traditional artificial evaluation of severity is greatly affected by subjective consciousness and lacks systematic standards. Here, we propose a hyperspectral evaluation method for quantifying salt-induced weathering on sandstone surfaces in laboratory tests. Our novel approach consists of two parts: data acquisition of microscopic observations of sandstone in salt-induced weathering environments, and machine learning technology for a predictive model. We first obtain the microscopic morphology of sandstone surfaces by near-infrared hyperspectral imaging technique. Then, a salt-induced weathering reflectivity index is proposed according to analyses of spectral reflectance variation. Next, a principal components analysis-Kmeans (PCA-Kmeans) algorithm is applied to bridge the gaps between the salt-induced weathering degree and the associated hyperspectral images. Furthermore, machine learning technologies, such as Random Forest (RF), Support Vector Machine (SVM), Artificial Neural Network (ANN), and K-Nearest Neighbors (KNN), are trained for better evaluating the salt-induced weathering degree of sandstone. Tests demonstrate that the RF algorithm is feasible and active in weathering classification based on spectral data. The proposed evaluation approach is finally applied to the analysis of salt-induced weathering degree on Dazu Rock Carvings.

Determination of Peach Gum in Ancient Chinese Paintings by Biotin–Streptavidin-Enzyme-Linked Immunosorbent Assay

ABSTRACT Peach gum was the most common and widely used exudate gum in ancient China. In this study, polyclonal antibodies to peach gum were prepared using the protein of peach gum as the antigen. The polyclonal antibodies were used to identify peach gum with high sensitivity and specificity by biotin–streptavidin-enzyme-linked immunosorbent assay (BA-ELISA). The binders used in the ancient paintings of the Forbidden City and the Dazu Rock Carvings were detected by enzyme-linked immunosorbent assay (ELISA). The results showed that the binders of the Dazu Rock Carvings were diverse, including collagen, ovalbumin, casein, peach gum, and lacquer, and that collagen and peach gum coexisted in most samples of the Forbidden City. This study demonstrates ELISA's high efficiency in analyzing binders in ancient paintings.

Visualizing water seepage dynamics in grotto relics via atom-based representative model

Water seepage in grotto relics, i.e., Yungang Grottoes, Dazu Rock Carvings, is a key issue to accurately describe the deterioration and weathering process of grotto rock mass. Considering rainfall infiltration, Finite element simulation was performed for studying the water flow through macro-channel of fractured rock in the 4th cave of Yungang Grottoes, where a group of joints with directions of S62°E and N5°W are widely developed. A 3D atom-based representative model was derived from X-ray diffraction (XRD) patterns and the related semi-quantitative calculation of grotto rock powders, for visualizing the associated seepage characteristics through micro-channel by means of molecular dynamics simulation, for the first time. By analyzing various properties, ranging from the configuration and energetic behaviors to the dynamic characteristics, the calculated water flux and mass flow rate were equal to 270 ns−1 and 8.10 × 10–12 g s−1, respectively. A dynamic process of water transport from the entrance region to the exit region was examined and it is consistent with the relative concentration profiles at the corresponding stage. The tagged O atoms experienced a zigzag movement instead of linear motion as expected, roughly exhibited the same target direction. The seepage characteristics in grotto relics experienced a complex evolution process and three types can be summarized: water infiltrates through micro-channels with a low flow rate; it flows through fracture with a relatively high flow rate; it turned into a kind of analogous pipe flow in inter-connected fracture network, resulting in water seepage hazard. Current simulation studies provide helpful insights for understanding the water flow-infiltration behavior of fractured rock in grotto relics.

Gender recognition of Guanyin in China based on VGGNet

Gender transformation of Guanyin (Avalokitesvara in India) in China is an intrinsically fascinating research topic. Besides the inner source from the scriptures, literatures and epigraphs, iconological analysis is usually as the external evidence of Guanyin’s gender recognition. However, the ambiguous gender of the Guanyin image is often intentional and can be objectively assessed. Can computer vision be applied to the recognition objectively and quantitatively? In this paper, VGGNet (VGGNet is a very deep convolutional network for large-scale image recognition proposed by Visual Geometry Group of Oxford University) is applied to propose an automatic gender recognition system. To validate its efficiency, abundant experiments are implemented on the images of Dazu Rock Carvings, Dunhuang Mogao Caves, and Yungang Grottoes. The following conclusions can be made according to the quantitative results. Firstly, VGG-based method can be effectively applied to the gender recognition on non-Buddhist and Buddhist images. Compared with five classical feature extraction methods, VGG-based method performs not much better on non-Buddhist images, but superior on Buddhist images. Furthermore, the experiments are also carried out on three different training datasets, real-world facial datasets, including CUHK (CUHK is a student face database of Chinese University of Hong Kong). IMFDB (IMFDB is an Indian movie face database.) and CAS-PEAL (CAS-PEAL is a Chinese face database created by Chinese Academy of Sciences (CAS) with varying pose, expression, accessory, and lighting (PEAL). The unsatisfactory results based on IMFDB indicate that it is not valid to apply Indian facial images as a training set to the gender recognition on Buddhist image in China. With the sinicization of Buddhism, there were more Chinese rather than Indian characteristics on Buddhist images in ancient China. The results based on CAS-PEAL are more robust than those based on CUHK, as the former is mainly composed of mature adult faces, and the latter consists of young student faces. It gives the evidence that Buddha and Bodhisattva (Guanyin included) were as ideally mature men in original Buddhist art. The last but the most meaningful is that besides the time factor, the relationship between image making and the scriptures, or the intentional combination of male and female features, the geographical impact should not be ignored when we talk about the gender transformation of Guanyin in ancient China. The gender of Guanyin frescoes in Dunhuang Mogao Caves painted in the Sui, Tang, Five, Song and Yuan dynasties were always with prominent male characteristics (with tadpole-like moustache), while bodhisattvas in Yungang Grottoes engraved in the Northern Wei Dynasty were feminine even though they were made earlier than those in Dunhuang Mogao Caves. It is quite different from the common idea that the feminization of Guanyin occurred in the early Tang Dynasties and completely feminized in the late Tang Dynasty. Both the quantitative results and image analysis indicate that there might be a common model in a specific region, so the image-making of Guanyin was affected much more by geographical rather than temporal factor. In a word, it is quite a complicated issue for the feminization of Guanyin in China.

Comprehensive Analysis of the Surface Decoration Layer of Buddha Statues from Dazu Rock Carvings in China

The surface decoration layers of Samantabhadra Bodhisattva and Thousand Hand Guanyin from Dazu Rock Carvings were examined using digital microscopy, energy-dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and pyrolysis—gas chromatography/mass spectrometry using thermally assisted hydrolysis and methylation. Gypsum was present in the preparation layer, while the painted layer included lacquer sap (urushiol). The presence of heat-bodied tung oil and resin (benzoin resin) was also detected in some painted layers. Mineral pigments were found in the painted layers, including cinnabar, lead red, orpiment, litharge, and carbon. In addition, there was a layer of gold foil on the surface of the Thousand Hand Guanyin sample. The mass percentage of gold was 96.70%. The gold foil contained gold, silver, copper, and iron as a solid solution. This study provides a reference for the study and protection of cultural relic samples from grottoes.

Experimental study on capillary water absorption of sandstones from different grotto heritage sites in China

Sandstone grottoes, with their elaborate carvings and decorations, hold high historic, artistic and scientific values and therefore constitute an important part of China’s stone cultural heritage. Although capillary water accounts for severe pathologies at the grottoes, so far there have been limited comprehensive investigations concerned with the capillary water absorption behavior of sandstones. Aiming at three significant and famous sites in China, i.e., Yungang Grottoes (YG), Dazu Rock Carvings (DZ) and Leshan Grand Buddha (LS), capillary water absorption tests were performed on samples from local sandstones. During the test, evolution of cumulative inflow was measured and variation in the height of capillary rise over time was also monitored by combining visual observation and infrared thermography. Scanning electron microscope and mercury intrusion porosimetry were adopted to characterize the pore structure. The results indicate that all the tested sandstones had a medium capacity of water uptake. Kinetics for capillary water absorption was the highest for LS sandstone and the lowest for DZ sandstone. Differences in macroscopic properties were contributed to microstructural features such as average pore diameter and pore size distribution. An irregular shaped water front was only observed in LS sandstone due to its heterogeneity. Infrared thermography provides an efficient and nondestructive way to detect the transition zone between wet and dry portions of the sample, which was not visible to the naked eyes. A proper understanding of the interaction of the sandstones with capillary water is essential for revealing the deterioration of grottoes and the underlying mechanisms.

Salt weathering of sandstone under dehydration and moisture absorption cycles: An experimental study on the sandstone from Dazu rock carvings

AbstractSalt crystallization and phase change in porous media cause significant deterioration of cultural heritage made of stones and bricks. In this study, laboratory experiments on salt weathering of sandstone from the Dazu rock carvings (DRC) in Chongqing, southwest China, were carried out by exposing them to cycles of temperature and humidity change. Mirabilite, the main component of the salts in DRC that readily undergoes phase change, was utilized for the study. Three groups of Dazu sandstone (DS) samples with high (2.4 mol/L), moderate (1.5 mol/L) and low concentrations (1.0 mol/L) of sodium sulphate were prepared; and two conditions, high‐temperature with low‐humidity and low‐temperature with high‐humidity, were designed to simulate the fluctuations of temperature and humidity in the Dazu area. After several cycles, the dehydration and moisture absorption of DS under these two conditions forces the phase change of sodium sulphate between thenardite (Na2SO4) and mirabilite (Na2SO4·10H2O), causing different levels of damage. A combination results of sample length, weight, microstructure, and mechanical property variations show that the damage effect of the thenardite formed during dehydration is more significant than that of mirabilite in moisture absorption. During these cycles, there is noticeable salt migration and the local concentration of salts is influenced by the microstructure of the stone and the distribution of clay minerals. Samples with high salt content show disintegration of the stone into powder, while those with moderate salt concentration show flaking and salt accumulation on the surface. These types of damage correspond with observations of natural weathering in the field. The experiment shows that no obvious damage takes place when the salt content is lower than 0.67%. These results contribute to a better understanding of the effects of salt weathering on sandstone and provide references for choosing correct prevention and protection measures for the world heritage site DRC.

Study on weathering mechanism of sandstone statues in Southwest China: example from the sandstone of Niche of Sakyamuni Entering Nirvana at Dazu Rock Carvings

To understand the weathering mechanism of sandstone statues in Southwest China, the sandstone of Niche of Sakyamuni Entering Nirvana at Dazu Rock Carvings was sampled. The three experiments were set up, including dry–wet cycle, freeze–thaw cycle and acid rain cycle. In this study, the mass, surface hardness, P-wave velocity were applied to explore the sandstone weathering degree over multiple cycles (for a total of 100 periods, 700 days). Various devices (i.e., X-ray diffraction, scanning electron microscope) were adopted to analyse the sandstone weathering mechanism. The experimental results showed that the deteriorated features of samples were the granular disintegration under the different experimental conditions, and the samples showed a decreased trend as a whole in the mass, surface hardness and P-wave velocity with the increase of periods. The sandstone deterioration by water occurred from the surface to the inner, and it was more serious with the increase of periods. The deterioration degrees affecting the granular disintegration of sandstone followed this order: acid rain cycle, freeze–thaw cycle, dry–wet cycle. Notably, higher H+, concentrations would enhance the sandstone deterioration. The sandstone of the bedding development was more easily to form the granular disintegration. The sandstone experienced the granular disintegration due to the combined effects of the internal factors (i.e., the dissolution of calcite, alteration of feldspar and water swelling and drying shrinkage of smectite on account of moisture) and external factors (i.e., the acid rain, temperature and humidity). The findings could provide useful insights for the protection of the studied statues, and the corresponding theories and methods had important guiding significance for the protection of grottoes in Southwest China.

Stability Monitoring and Deformation Laws of the Yuanjue Cave in the Influence Zone of the Unloading Zone

As a representative of cliff-like stone cultural relics, caves are carved on natural mountains and cliffs, which overlap with the influence zone of the geological unloading zone. Cracks in the unloading zone lead to stability issues, including falling blocks, collapse, water seepage, and deformation. This article analyzes the stability of the roof facing the Yuanjue Cave, the cultural heritage site of Dazu Rock Carvings. We systematically analyzed the characteristics of the Yuanjue Cave and established a method to monitor cave stability based on the framework of the protection system. As shown through in-field practice, the monitoring method showed good modularization, construction, and spatial expansion performance in narrow spaces. Taking fracture displacement, roof subsidence, roof denudation rates, and roof pressure as monitoring elements, the method showed high precision over a short timeframe. The deformation law of the surrounding rock mass was also obtained through coupling the analysis of multisource monitoring data in the Yuanjue Cave. The method could integrate protection and monitoring systems, permitting preservation of the Yuanjue Cave and its cultural relics, providing a useful reference for similar cases.

Numerical Modeling and Stability Analysis of Surrounding Rock of Yuanjue Cave

Yuanjue Cave, located in Big Buddha Bay, Mount Baoding, Dazu Rock Carvings Area, has extremely high historical, artistic, and religious value and is an important grotto cultural relic in China. Due to the cutting action of the fissures and weak interlayers, the South Cliff of Big Buddha Bay where Yuanjue Cave is located showed signs of instability. In order to fully evaluate the stability of the rock mass around the cliff where Yuanjue Cave is located, a three-dimensional geological model of the surrounding rock of Yuanjue Cave was established by using FLAC3D software, combined with three-dimensional scanning, fissure investigation, and indoor tests. The stability of the surrounding rock mass adjacent to Yuanjue Cave has been studied by precise numerical simulation, and the results of numerical simulation and monitoring have been compared and analysed. The results show the following: (1) The west of J10 fissure, above the mudstone interlayer, is the main deformation area. The cliff displacement increases gradually from the east to the west. The independent block above the corner has the largest free space displacement, and there is a risk of independent collapse. Special attention should be paid to the stability of this block. The displacement of the upper monitoring point of the cliff wall is significantly greater than that of the lower layer. (2) In the surrounding rock block in the adjacent area, the various concentrated stresses of the body are mainly located at the entrance of Yuanjue Cave, the height of the chest of the Zhengjue Buddha statue, and the lower mudstone erosion and reinforcement zone. Among them, the stress concentration in the erosion and reinforcement area under the Zhengjue Buddha statue is the largest. The conclusions obtained can provide a useful reference for the stability assessment of the surrounding rock of Yuanjue Cave.

Stability Evaluation of Deformation (Denudation) of Yuanjue Rock Cave Roof Based on Multisource Monitoring

The grotto rock mass is a type of cave structure, formed under the complex forces of environment, geology, and human interventions. Many scholars have carried out a lot of work in the protection of cultural relics. However, the research on detection and monitoring methods based on the parametric evolution system remains incomplete. In recent years, with the intersection and integration of disciplines, IoT (IoT: Internet of Things) systems and sensor technologies have developed rapidly. Under this background, a new monitoring system suitable for the protection of cultural relics was independently developed and applied to the protection and research work of Yuanjue rock cave, and the system was corrected and improved in practice. In this paper, according to the complex force characteristics of the sandstone roof of the Yuanjue rock cave at Dazu Rock Carvings and the geological conditions. Initially, a detailed survey of the geological conditions of the Yuanjue rock cave area was conducted; furthermore, according to the unique structural and load characteristics of the outer and inner surfaces of the roof, the monitoring methods and principles of each main control factor were explored, while the layout of monitoring points was optimized; finally, based on the microsensing technology, intelligent high-precision sensing hardware was installed and debugged for each main control factor, while the network was formed to form a multisource monitoring IoT system for the roof stability of the circular sense hole. After nearly half a year of continuous monitoring, the deformation and denudation rules of the roof of Yuanjue Cave were revealed, and a new approach of evaluating roof stability was proposed. This research provided technical support and research ideas for monitoring the stability of similar cultural relics.

Degradation of emerald green: scientific studies on multi-polychrome Vairocana Statue in Dazu Rock Carvings, Chongqing, China

The spontaneous degradation of pigments in painting may occur depending on environment, especially the surrounding condition of high humidity and soluble salts. Even some of these are well studied, more investigations are still in need for heritage science. Paint cross sections from Vairocana Statue in Dazu Rock Carvings, one of World Cultural Heritage, Chongqing, China are studied by optical microscopy (OM), Raman spectroscopy (Raman) and mapping, and scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM–EDS). Ultramarine blue, emerald green, synthetic atacamite, vermilion, red lead, gold foil, orpiment, cerussite, gypsum and barite are identified as pigments. Moreover, lavendulan (NaCaCu5(AsO4)4Cl·5H2O) and mimetite (Pb5(AsO4)3Cl) are degradation products of emerald green (Cu(C2H3O2)2·3Cu(AsO2)2) and cerussite(PbCO3) originally used as green pigment with mixture. These secondary products are formed via multistep progresses as degradation of emerald green and cerussite, oxidation of arsenite ((AsO2)−), migration of arsenate ((AsO4)3−) and precipitation reaction of these ions with other necessary ions from environmental conditions. Based on the pigment and paint layer stratigraphy analysis, the paintings of the statue have been executed at least four times and the most recent may be after 1850s. The formation of lavendulan give rise to a highlight for identification of green copper-arsenic containing pigments and characterization of degradation in complex conditions.

Virtual Inpainting for Dazu Rock Carvings Based on a Sample Dataset

Numerous image inpainting algorithms are guided by a basic assumption that the known region in the original image itself can provide sufficient prior information for the guess recovery of the unknown part, which is not often the case in actual art-image inpainting. Sometimes, the art image that needs to be inpainted is so badly damaged that there is little prior information to serve as a good model to infer the appearance of the unknown fragment. Focusing on the lookup strategy for optimal patches, a novel semi-automatic exemplar-based inpainting framework based on a sample dataset is proposed in this article to solve such a problem with three steps: (1) reference images selection from the dataset using deep convolutional network, (2) sample image creation based on reference images with melding algorithm, and (3) exemplar-based inpainting according to the created sample image. Several comparative experiments over Dazu Rock Carvings with the state-of-the-art image completion approaches demonstrate the effectiveness of our contributions. First, the search space for candidate patches is extended from the known region to a sample image. It performs effectively for the inpainting case of little prior information existing in the original image itself. Furthermore, sample image creation is added to reduce the complexity of inpainting via multiple images and avoid the taboo of complete duplication in art restoration. Moreover, Poisson blending is used for post-procedure to improve the visual harmony between the reconstructed fragment and the known region in both color and illumination. Last but not least, our method is successfully applied in the virtual inpainting of Dazu Buddhist face images. The inpainted proposals can be a reference for the final actual artificial inpainting as well as a base for VR show.

Surface weathering characteristics and degree of Niche of Sakyamuni Entering Nirvana at Dazu Rock Carvings, China

Study on the weathering characteristics of Niche of Sakyamuni Entering Nirvana at Dazu Rock Carvings is the first step of scientific conservation. Based on the in-depth investigation on the weathering characteristics of Niche of Sakyamuni Entering Nirvana, the weathering degree was measured and evaluated by means of the in-situ non-destructive surface hardness test and ultrasonic test. The results reveal that the weathering types of Niche of Sakyamuni Entering Nirvana consist of granular disintegration, salt efflorescence, scaling, blistering, cracking, missing parts, biological colonization, and water seepage. The weathering degree of the head and foot of the statues are higher than that of the chest and abdomen in the horizontal direction, and the weathering degree of the upper parts of the statues and the ground area are higher than that between them in the vertical direction. The results of surface hardness and ultrasonic velocity are in close accordance with the weathering degree of the statues. Sedimentary and structural characteristics of sandstone lay a material foundation for various weathering characteristics and degree. The research results pave the way for condition assessment, intervention decision-making, and preventative conservation of the studied statues.

Study on Mechanism of Water Condensation and Field Experiments of Thousand-Hand Guanyin in Dazu Rock Carvings

Dazu Rock Carvings is an important heritage. In the past, many varieties of damages existed in Dazu Rock Carvings, which impaired aesthetics and safety. Thus, the country is trying to save the rock carvings through preservation of cultural relics. Among those engaged in this endeavor are leaders and experts from Dazu Rock Carving Institute, Chinese Academy of Cultural Heritage, China University of Geosciences, School of Environment of Tsinghua University. In the research hereof, field experiments and field surveys were carried out, and corresponding measures were put forward for analysis of data.

Average-face-based virtual inpainting for severely damaged statues of Dazu Rock Carvings

Abstract Numerous image inpainting algorithms are guided by a basic assumption that the known region in the original image itself can provide sufficient prior information for the guess recovery of the unknown part, which is not often the case in actual art image inpainting. In order to solve the challenging inpainting case that there is little image prior in the remainder of the original image, we propose an average-face-based inpainting method based on a sample database with 3 steps: reference images selection, average image generation and exemplar-based image inpainting. In which, average image generation is crucial. In the inpainting framework, the average image can be directly viewed as an inpainting proposal for the severely damaged or absolutely lost image. Moreover, the average image can be applied to exemplar-based inpainting algorithm as a sample image to extend the searching region for match patch, so as to perform the restoration for images with large-scale or irregularly damaged holes. The inpainting experiments over some facial images of Dazu Rock Carvings demonstrate the validity and effectiveness of our method. It is first utilized for two extremely challenging inpainting tasks: reconstruction for the stolen head of Willow Avalokitesvara in Shimenshan No. 6 and the absolutely broken heads of two Avalokitesvaras in Beishan No. 180. Compared to the failure of the exemplar-based inpainting algorithm within the original image and the directly duplication of a similar image, the generated average image can be as a more reliable inpainting proposal. The comparative experiments also show the efficiency and advantage of the average face applied to exemplar-based inpainting framework. Compared with some related inpainting algorithms, our method is more competitive when there is little prior information in the original image. The efficient virtual inpainting results are valuable references for both cave art historians and conservators.