Search Results (64)

During the long-term preservation of murals, the degradation of mural image information poses significant challenges to the restoration and conservation of world cultural heritage. Currently, mural conservation scholars focus on image segmentation techniques for mural restoration and protection. However, existing image segmentation methods suffer from suboptimal segmentation quality. To improve mural image segmentation, this study proposes an efficient mural image segmentation method termed Adaptive Nonlinear Bernstein-guided Parrot Optimizer (ANBPO) by integrating an adaptive learning strategy, a nonlinear factor, and a third-order Bernstein-guided strategy into the Parrot Optimizer (PO). In ANBPO, First, to address PO’s limited global exploration capability, the adaptive learning strategy is introduced. By considering individual information disparities and learning behaviors, this strategy effectively enhances the algorithm’s global exploration, enabling a thorough search of the solution space. Second, to mitigate the imbalance between PO’s global exploration and local exploitation phases, the nonlinear factor is proposed. Leveraging its adaptability and nonlinear curve characteristics, this factor improves the algorithm’s ability to escape local optimal segmentation thresholds. Finally, to overcome PO’s inadequate local exploitation capability, the third-order Bernstein-guided strategy is introduced. By incorporating the weighted properties of third-order Bernstein polynomials, this strategy comprehensively evaluates individuals with diverse characteristics, thereby enhancing the precision of mural image segmentation. ANBPO was applied to segment twelve mural images. The results demonstrate that, compared to competing algorithms, ANBPO achieves a 91.6% win rate in fitness function values while outperforming them by 67.6%, 69.4%, and 69.7% in PSNR, SSIM, and FSIM metrics, respectively. These results confirm that the ANBPO algorithm can effectively segment mural images while preserving the original feature information. Thus, it can be regarded as an efficient mural image segmentation algorithm. Full article

Preserving heritage sites is a complex challenge that requires multidisciplinary approaches, combining scientific accuracy with cultural and historical sensitivity. In alignment with UNESCO’s conservation guidelines, this study investigated the airflow dynamics and wind-induced structural effects within ancient architecture using advanced computational fluid dynamics (CFD). The study site was the Na Phra Meru Historical Temple in Ayutthaya, Thailand, where the shear stress transport $k-\omega$ turbulence model was applied to analyze distinctive airflow patterns. A high-precision 3D computational domain was developed using Faro focus laser scanning technology, with the CFD results being validated based on onsite experimental data. The findings provided critical insights into the temple’s ventilation behavior, revealing strong correlations between turbulence characteristics, wind speed, temperature, and relative humidity. Notably, the small slit windows generated complex flow mixing, producing a large internal recirculation zone spanning approximately 70% of the central interior space. In addition to airflow distribution, the study evaluated the aerodynamic forces and rotational moments acting on the structure based on five prevailing wind directions. Based on these results, winds from the east and northeast generated the highest aerodynamic loads and rotational stresses, particularly in the lateral and vertical directions. Overall, the findings highlighted the critical role of airflow and wind-induced forces in the deterioration and long-term stability of heritage buildings. The study demonstrated the value of integrating CFD, environmental data, and structural analysis to bridge the gap between conservation science and engineering practice. Future work will explore further the interactions between wall moisture and the multi-layered pigments in mural paintings to inform preservation practices. Full article

Guomari fortress in eastern Qinghai Province exemplifies vernacular architecture shaped by multiethnic interaction, environmental adaptation, and localized defense strategies. Originally a Ming Dynasty military-agricultural outpost, it evolved into a Tu ethnic settlement. Fieldwork, including architectural surveys and spatial analysis, identified a three-tiered defensive system: (1) strategic use of terrain and rammed-earth walls; (2) labyrinthine alleys with L-, T-, and cross-shaped intersections; and (3) interconnected rooftops forming elevated circulation routes. Courtyards are categorized into single-line, L-shaped, U-shaped, and fully enclosed layouts, reflecting adaptations to terrain, ritual functions, and thermal needs. Architectural features such as thick loam-coated walls and flat roofs demonstrate climatic adaptation, while the integration of Han timber frameworks, Tibetan prayer halls, and Tu decorative elements reveals cultural convergence. Traditional craftsmanship, including carved wooden scripture blocks and tsampa-based murals, is embedded within domestic and ritual spaces. The fortress’s circulation patterns mirror Tibetan Buddhist cosmology, with mandala-like alleys and rooftop circumambulation routes. These findings offer insights into vernacular resilience and inform conservation strategies for multiethnic fortified settlements. Full article

The colour degradation of murals presents a significant challenge in the conservation of architectural heritage. Previous research has often concentrated on localized pigment changes while paying insufficient attention to the interaction between colour variation and indoor environmental conditions. Although non-destructive analytical techniques are widely used in heritage studies, their integrated application in combination with colourimetry has been limited, particularly in the context of Tibetan Buddhist murals in highland continental climates. This study investigates the murals of Liuli Hall in Meidai Lamasery, Inner Mongolia, as a representative case. We employed a comprehensive methodology that combines non-destructive analytical tools, gas chromatography–mass spectrometry, and quantitative colour analysis to examine pigment composition, binding material, and surface deterioration. Through joint analysis using the CIE Lab and CIE LCh colour space systems, we quantified mural colour changes and explored their correlation with material degradation and environmental exposure. The pigments identified include cinnabar, atacamite, azurite, and chalk, with animal glue and drying oils as binding materials. Colourimetric results revealed pronounced yellowing on the east and west walls, primarily caused by the ageing of organic binders. In contrast, a notable reduction in brightness on the south wall was attributed to dust accumulation. These findings support tailored conservation measures such as regular surface cleaning for the south wall and antioxidant stabilization treatments for the east and west walls. Initial cleaning efforts proved effective. The integrated approach adopted in this study provides a replicable model for mural diagnostics and conservation under complex environmental conditions. Full article

In response to the urgent need for the sustainable conservation of cultural heritage against the backdrop of climate change and environmental degradation, this study proposes a low-cost, non-destructive digital recording method for murals based on close-range photogrammetry. By integrating non-metric digital cameras, total stations, and spatial coordinate transformation models, high-precision digital orthophoto generation for indoor murals was achieved. Experimental results show that the resolution error of this method is 0.02 mm, with root mean square errors (RMSE) of 3.51 mm and 2.77 mm in the X and Y directions, respectively, meeting the precision requirements for cultural heritage conservation. Compared to traditional laser scanning technology, the energy consumption of the equipment in this study is significantly reduced, and the use of chemical reagents is avoided, thereby minimizing the carbon footprint and environmental impact during the recording process. This provides a green technological solution to address climate change. Additionally, the low-cost nature of non-metric cameras offers a feasible option for cultural heritage conservation institutions with limited resources, promoting equity and accessibility in heritage protection amid global climate challenges. This technology provides sustainable data support for long-term monitoring, virtual restoration, and public digital display of murals while also offering rich data resources for virtual cultural tourism, public education, and scientific research. It demonstrates broad application potential in the context of climate change and environmental protection, contributing to the green transformation and sustainable development of cultural tourism. Full article

The main purpose of the review is to analyze the terminology and methodologies for conservation treatment in cultural heritage conservation, in particular, to define key terminology (such as quality, compatibility, efficacy, and durability); to identify methodologies for assessing conservation interventions; to examine case studies where these assessment techniques have been applied. A summary of the various definitions of terms such as quality, compatibility, efficacy and durability found in the literature is provided. This is followed by a presentation of some theoretical approaches found in the literature on how to evaluate different aspects of conservation interventions. Some more practical examples are then considered, with a focus on mural paintings. Finally, the importance of monitoring interventions over time in the context of preventive conservation is highlighted. The present review emphasizes that key concepts such as compatibility, efficacy, and durability are inherently flexible and context-dependent, often overlapping and evolving according to cultural heritage typology, intervention methods, and environmental conditions. Full article

Microbes colonizing cultural artifacts are a ubiquitous phenomenon which may occur during burial, post-excavation, and storage periods, thereby seriously affecting sustainable heritage conservation. In this study, high-throughput sequencing technology was applied to analyze the microbial community structure in ancient mural paintings and the surrounding air, as well as to identify the most characteristic taxa causing black spot contamination. The results showed that members of the genera Gliomastix and Ochroconis were highly abundant in black-spots-contaminated areas and rarely detected in the air and uncontaminated mural paintings. Air samples of the two tombs showed no significant difference in Chao1 and Shannon indices, whereas statistically significant differences were observed compared to those samples collected from black spots. The taxonomic diversity of the microbial community in the soil-covered mural paintings and air exhibited similar structures at the genus level. Moreover, when compared to other areas of the two tombs, the samples from black spots differed not only in microbial community composition but also in microbial assembly processes and the co-occurrence patterns, such as much less network complexity in the black spots area. Functional predictions uncover the presence of microbial functional profiles involved in nitrogen cycling, organic matter degradation, and animal and human pathogens, representing a potential threat to cultural relics and public health. These results advance our understanding of the impacts of archeological excavations on the microbial community variation in tomb mural paintings. Full article

Painted surfaces, regardless of their substrate, possess unique elements crucial for their study and interpretation. These elements include geometric characteristics, surface texture, brushwork relief, color layer morphology, and preservation state indicators like overpainting, interventions, cracks, and mechanical deformations. Traditional recording methods such as handwritten or digital descriptions, 2D scale drawings, calipers, rulers, tape measures, sketches, tracings, and conventional or technical photography fall short in capturing the three-dimensional detail necessary for comprehensive analysis. To overcome these limitations, this paper proposes the integration of two digital tools, Close-Range Photogrammetry (SfM-MVS) and Reflectance Transformation Imaging (RTI), which have become accessible with the advancement of computing power. While other 3D imaging tools like laser scanners and structured light systems exist and may be preferred for very specialized applications, such as capturing the texture of the surface with sub-millimeter accuracy, SfM-MVS and RTI offer a cost-efficient and highly accurate alternative, with 3D modeling capabilities and advanced pixel color fidelity, essential for documenting the geometric and color details of painted artifacts. The application of these highly promising methods to the mural paintings from the Palace of Tiryns (Nafplion, Greece) demonstrates their potential, providing significant insights for art historians, researchers, conservators, and curators. Full article

In October 2021, a mural painting was discovered in the crypt of Parma Cathedral (Italy). It was covered by a wall, erasing it form historical memory. The painting, presumably from the 15th–16th century, depicts the Madonna and Child enthroned in the center, between Saints Peter and John. Before the restoration project, investigations were conducted with different techniques to identify the pigments and binders used, the nature of the surface finish and the efflorescence. Micro-Raman spectroscopy detected numerous pigments compatible with the presumed age. An interesting result concerns the presence of crocoite (lead chromate), an unusual and rare pigment for this period. These pigments were confirmed through investigation by means of Scanning Electron Microscopy coupled to Energy-Dispersive X-ray Spectroscopy (SEM-EDS). Fourier Transform Infrared Spectroscopy (FT–IR) and Gas Chromatography/Mass Spectroscopy (GC/MS) were used to identify the binder and the type of wax used in the finish layer. The rather widespread presence of egg, used to spread the paint, allows us to affirm that this mural painting was created as a fresco, with substantial parts a secco. Full article

Contemporary muralism is a constantly expanding form of urban art, whose preservation is highly debated and for which no specific preventive conservation measures have been defined. The degradation of painting materials remains a dramatic issue as mural paintings undergo rapid and inevitable chemical–physical reactions, leading to their aesthetic decay and chemical–mechanical disintegration. This work started with interviews with, and questionnaires given to experts in the field from which various needs emerged, including defining a testing protocol for the study of the compatibility and effectiveness of organic coatings to protect street art painted surfaces. Five protective formulations available on the market were selected and applied on mock-ups realized with three different types of paintings (alkyd, acrylic, and styrenic). The efficacy and affinity of the five protective treatments in relation to the different underlying painting layers were investigated. The adopted testing protocol enabled understanding the protection efficacy and compatibility of the different tested formulations in relation to the type of painting and wall preparation. The typology of the underlying paint mainly influences the final aesthetic result, while the application of the primer may play a relevant role in terms of the protection effectiveness, confirming the importance of pre-treating the substrate before painting. The results clearly show that there is still no specific and effective protection system that is appropriate for all commercial paints used by street artists. Full article

Microbial deterioration poses a significant threat to built heritage, particularly mural paintings, where traditional synthetic biocides can have adverse environmental and material impacts. This study evaluates the effectiveness of essential oils derived from four aromatic plants—thyme (Thymus mastichina L.), fennel (Foeniculum vulgare Mill.), pennyroyal (Mentha pulegium L.), and green lavender (Lavandula viridis L’Hér.)—as natural biocides against microorganisms isolated from mural paintings in the House of Moscadim, an 18th-century manor house in Portugal. The antimicrobial activity of the essential oils was assessed using both direct contact and micro-atmosphere methods. Four microorganisms were isolated, including two bacteria, Bacillus wiedmannii and Bacillus mobilis, and two fungi, Penicillium brevicompactum and Cladosporium cladosporioides. Fennel essential oil exhibited the strongest antifungal activity against both fungal species, surpassing the efficacy of the commercial biocide Biotin T^® in some cases. Pennyroyal and lavender essential oils also showed significant inhibitory effects. The micro-atmosphere method demonstrated the potential for noninvasive application of essential oils while preserving the integrity of delicate mural surfaces. These findings suggest that essential oils, particularly fennel oil, constitute a promising natural alternative to synthetic biocides for the sustainable conservation of cultural heritage. Further research is recommended to explore their long-term effects and to optimize application techniques. Full article

Digital non-metric cameras with high-resolution capabilities are being used in various domains such as digital heritage, artifact documentation, art conservation, and engineering applications. In this study, a novel approach consisting of the application of the combined use of close-range photogrammetry (CRP) and mapping techniques is used to capture the depth of a mural digitally, serving as a database for the preservation and archiving of historic murals. The open hall next to the main sanctuary of the Virupaksha temple in Hampi, Karnataka, India, which is a UNESCO World Heritage site, depicts cultural events on a mural-covered ceiling. A mirrorless Sony Alpha 7 III camera with a full-frame 24 MP CMOS sensor mounted with a 50 mm lens and 24 mm lens has been used to acquire digital photographs with an image size of 6000 × 6000 pixels. The suggested framework incorporates five main steps: data acquisition, color correction, image mosaicking, orthorectification, and image filtering. The results show a high level of accuracy and precision attained during the image capture and processing steps. A comparative study was performed in which the 24 mm lens orthoimage resulted in an image size of 9131 × 14,910 and a pixel size of 1.05 mm, whereas the 50 mm lens produced a 14,283 × 21,676 image size and a pixel size of 0.596 mm of the mural on the ceiling. This degree of high spatial resolution is essential for maintaining the fine details of the artwork in the digital documentation as well as its historical context, subtleties, and painting techniques. The study’s findings demonstrate the effectiveness of using digital sensors with the close-range photogrammetry (CRP) technique as a useful method for recording and preserving historical ceiling murals. Full article

This research is focused on the laboratory study of salt crystallization inhibitor products as new materials for conservation treatments which can be applied to mortars and painted plasters; as is well known, salt crystallization is one of the most frequent causes of decay processes on decorated architectural surfaces in a wide range of environments. Specifically, the study targets the field of the preventive conservation of mural paintings within rupestrian heritage sites. For the first time, systematic investigations were performed on mock-ups made of plaster painted with two different pigments: yellow ochre and carbon black. Two types of phosphonate inhibitors, PBTC (2-phosphonobutane-1,2,4-tricarboxylic acid) and ATMP (aminotris (methylene phosphonic acid)), were chosen and applied at two different concentrations. Given the limited literature available, and the presence of pigments potentially sensitive to treatment with salt inhibitors, preliminary tests were required. Their effects on the chromatic features of the pigments were evaluated visually and using colorimetry. The changes in the behaviour of water circulation in the mortar resulting from the treatments were evaluated through water vapour permeability and absorption tests. Accelerated crystallization experiments were carried out to assess how inhibitors could influence the growth of salts and the resulting material damage. The latter was carried out by employing sodium sulphate and calcium sulphate solutions, quantifying the damage to the specimens through material loss in weight and the percentage of painted surface loss. Based on the overall results, the product with the best performance was identified was ATMP 0.1% (by volume) in deionized water. The obtained results show that salt inhibitor treatments are promising for in situ application and could represent an innovative approach to promote the sustainable conservation of mural painting, particularly those located in hypogeal contexts, where the salt supply cannot be removed and slowing the growth of salts and/or changing their crystalline habitus may be effective in limiting their damage. Full article

Hypogea are natural or artificial spaces located underground often of great interest from an anthropological, archeological, religious, artistic, or historic point of view. Due to their features, these environments usually present conservative problems and biological colonization could be considered as one of the main threats. The present three-year study was carried out by specialists of the Central Institute for Restoration of Rome (ICR) in the hypogeous site preserved in the Roman Archeological Museum of Positano (Positano MAR) and focused on characterizing biological alterations present on the mural paintings; setting up efficient strategies and protocols for biodeterioration control; and monitoring the efficacy of direct and indirect interventions. Patinas with different morphologies were analyzed through microscopic observations, cultural analyses and next-generation sequencing. The results proved that the alterations comprised a great variety of microorganisms forming very distinct communities, differently distributed over space and time. The main taxa represented were bacteria of phyla Pseudomonadota and Actinomycetota, fungi belonging to the genus Fusarium and Gliocladium, and algae of the genus Chlorococcum. Preservation protocols were set up considering the alterations’ composition and included the application of biocides, limiting daily temperature changes, decreasing illuminance values on painted surfaces, and the screening of natural light sources. Full article

This paper focuses on an integrated approach to study the materials and the degradation issues in the urban mural painting Ama Il Tuo Sogno, painted by the famous street artist Jorit Agoch in Matera (Italy). The study was conducted in the framework of a conservation project, aiming to contrast a progressive decay affecting the artifact that started a few months after its creation. Multi-analytical techniques were used to investigate the stratigraphy and chemical composition of the pictorial film within a low-impact analytical protocol for sustainable diagnostics. They included polarized light microscopy in UV and VIS reflected light, FTIR spectroscopy, Py-GC-HRAMS, and SEM-EDS. The mineralogical–petrographic composition of the mortar employed in the pictorial support was also studied with optical microscopy of thin sections and X-ray diffractometry. To know the mechanism underlying the degradation, IR thermography was performed in situ to establish the waterways and the distribution of the humidity in the mural painting. In addition, ion chromatography and X-ray diffractometry were used to identify and quantify the soluble salts and to understand their sources. The overall results allowed us to determine the chemical composition of the binder and pigments within the pictorial layers, the mineralogical–petrographic characteristics of the mortar of the support, and the execution technique of the painting. They also highlighted a correlation between the presence of humidity in the painted mural and the salt damage. The mineralogical phases were detected in the mural materials by XRD, and the results of ion chromatographic analyses suggested a supply of soluble salts mainly from the mortar of the support. Finally, the study provided basic knowledge for planning appropriate sustainable conservation measures. Full article