A web information system for the management and the dissemination of Cultural Heritage data

Safeguarding and exploiting Cultural Heritage induce the production of numerous and heterogeneous data. The management of these data is an essential task for the use and the diffusion of the information gathered on the field. Previously, the data handling was a hand-made task done thanks to efficient and experienced methods. Until the growth of computer science, other methods have been carried out for the digital preservation and treatment of Cultural Heritage information. The development of computerized data management systems to store and make use of archaeological datasets is then a significant task nowadays. Especially for sites that have been excavated and worked without computerized means, it is now necessary to put all the data produced onto computer. This allows preservation of the information digitally (in addition with the paper documents) and offers new exploitation possibilities, like the immediate connection of different kinds of data for analyses, or the digital documentation of the site for its improvement. Geographical Information Systems have proved their potentialities in this scope, but they are not always adapted to the management of features at the scale of a particular archaeological site. Therefore this paper aims to present the development of a Virtual Research Environment dedicated to the exploitation of intra-site Cultural Heritage data. The Information System produced is based on open-source software modules dedicated to the Internet, so users can avoid being software driven and can register and consult data from different computers. The system gives the opportunity to do exploratory analyses of the data, especially at spatial and temporal levels. The system is compliant to every kind of Cultural Heritage site and allows management of diverse types of data. Some experimentation has been done on sites managed by the Service of the National Sites and Monuments of Luxembourg.     

Fibre Optic Reflectance Spectroscopy as a non-invasive tool for investigating plastics degradation in contemporary art collections: A methodological study on an expanded polystyrene artwork

Fibre Optics Reflectance Spectroscopy (FORS) is a well-established technique, widely used in the conservation field for in situ investigations and non-invasive diagnostics on traditional artworks. Nevertheless, there is little knowledge on the use of this technique for investigating modern artists materials used in contemporary artworks. The present study, carried out within the wider framework of the EC funded Project “POPART” (Preservation of Plastic ARTefacts in museum collections”), was aimed at investigating the possibility of extending the applications of FORS to synthetic polymers, and proposing this technique as new non-invasive analytical tool for diagnostics on plastic artworks in museum collections. Thus, a real case was selected from the permanent collection of the Conteporary Art Centre “Luigi Pecci” (Prato, Italy). The artwork, created in 1990 by the artist Stefano Arienti, was entirely constituted of expanded polystyrene (EPS) and it showed diffused signs of degradation. The need of singling out the main causes of deterioration in order to prevent further damages was evident. An in situ FORS measurements campaign was performed with the aim of gaining in-depth information about its conservation state and identifying the main agents responsible for the observed degradation. Thanks to the non-invasivity of the technique an extensive spectroscopic characterisation of different areas of the EPS surface could be performed and the spectral data were exploited to build a map of the degraded areas of the artwork. Data acquired in field were compared with those obtained from laboratory test performed on artificially aged EPS samples. These results helped in ascertaining the detrimental actions of the light sources used to back illuminate the artwork. In particular, in this case FORS proved to be effective in detecting EPS alterations before the chromatic effects became visually evident. These results suggested that FORS may be considered as a good candidate to be used for non-invasive investigations also on some modern materials and contemporary artworks. The research was completed with an interview to the artist Stefano Arienti, whose point of view was constructively integrated with the scientific results obtained. This emphasized the importance of an interdisciplinary approach to the solution of conservative problem in the field of contemporary art.     

Generation of virtual models of cultural heritage

Different techniques and tools currently exist to generate three-dimensional models of small elements, buildings and cities. Apart from being easier to interpret than two-dimensional drawings, these models facilitate data necessary for reconstruction projects, preservation or rehabilitation of the architectural or archaeological heritage. Traditional surveying only enables us to obtain discrete information of the characteristic lines that define each surface, edge, slope change etc. whereas work with massive capture techniques allows us to obtain continuous points of the surfaces. Photogrammetry or laser scanning combined with conventional photography provides information of the building in addition to its geometry. We carried out a review of the different techniques showing the advantages and disadvantages of each technique as well as the information that can be obtained by applying these techniques to the survey of the great Gate of Antioch in the town of Aleppo, declared a World Heritage Site by UNESCO in 1986, in Syria.     

An integrated and automated segmentation approach to deteriorated regions recognition on 3D reality-based models of cultural heritage artifacts

In the field of Cultural Heritage, image analysis represents an indispensable practice for restorers to collect information about the state of preservation of monuments and artifacts and plan restoration interventions. In addition, during the last two decades, the wide spread of remote sensing technologies and the possibility to build 3D reality-based models of artifacts allow the extension of image analysis to 3D environments. In this context, the purpose of this contribution is to show the results of investigations held in order to provide a methodology for the automatic detection of deteriorated areas within architectures and artifacts using colour images as a field of examination. Using both 2D and 3D segmentation approaches, our methodology aims at speeding and efficiently performing the automatic detection of deteriorated zones within Cultural Heritage and therefore segment 3D digital models acquired using different survey technologies. Within our investigations, we selected case studies concerning recurrent deteriorations, such as, for example, detachments, cracks and chromatic alterations; we run them both to manual and to automatic recognition and selection tests, in order to compare the results obtained using these approaches and evaluate the reliability of the automatic one. Results comparison included computational and user time, quantification of the deteriorated area error between manual and automatically detected zones. Additional parameters characterizing the specific type of deteriorations were also computed for each case study. Comparison between the automatic and the manual procedure showed that the automatic detection is faster and reliable in all our selected case studies, with evident improvements in the efficient evaluation of the entity and extension of deteriorated areas on 3D geometry.     

AI and virtual crowds: Populating the Colosseum

Computer technologies and digital recreations have been widely used in the field of Cultural Heritage in the past decade. However, most of the effort has concentrated in accurate data gathering and geometrical representation of buildings and sites. Only very recently, works are starting to go beyond that approach by including digital people. The impressive development of computer graphics techniques and computing power, makes now possible the creation and management of virtual environments where a big number of virtual creatures interact and behave in a smart manner.In this paper we present a novel use of virtual crowds for Cultural Heritage: we use them to predict behaviors, or to help scholars draw more educated conclusions on unknown matters. We specifically present a case study based on an artificial intelligence crowd simulation which is being used by scholars to study the ergonomics of the Roman Colosseum: it was formerly believed to be an excellent people-mover, but currently that belief is seriously questioned, as potential bottlenecks seem to have been detected.     

Surface analysis of stone materials integrating spatial data and computer vision techniques

This paper deals with a possible application of computer vision techniques in the field of Cultural Heritage. These techniques allow an effective integration of data from different sources. Particular consideration will be given to an accurate geometric analysis of the zone under study in order to detect degradation damage in historical building-stone materials. To this end, we employ a computer vision technique, known as the Shape from Shading method, for which a photographic image of the stone material under consideration is the only input data required. By using this method, it is possible to recover, under some constraints, the shape of the three-dimensional surface of the object from the photographic image. In order to improve the results, in this paper, we implement this technique by using an optimization approach which allows a suitable integration of photographic and spatial data, the latter of which is obtained by a topographical device. We outline the potentialities of the method which mainly consist of two relevant capabilities. The first one is the geometric shape reconstruction of the surface material at a resolution much higher than the one allowed by topographical acquisition. The second one is the correction of the lighting-induced distortions in the photographic image. Such a correction is relevant for further image-based analysis of the degradation of the stone material. Experimental results, obtained by using both photographic and spatial data relative to a pudding stone with degradation, are presented and discussed.     

Daily natural heat convection in a historical hall

The use of numerical simulation methods for the Cultural Heritage is of increasing importance for the analysis, conservation, restoration and appreciation of works of art. This is particularly important when their preservation and planned maintenance is the primary aim. Today museums, and particularly historical buildings converted to museums, should be considered as places where precious artefacts should have first-rate protection and conservation. It is a question of solving the compromise between protection, conservation and comfort for works of art and/or visitors, with the consequence that preservation and planned maintenance criteria must prevail over use requirements. Refurbishment and conservation of a building, and requirements for visitor presence and works of art need different thermo-physical indoor parameter values. The present paper concerns the thermal and air velocity analysis of the Salone dei Duecento (the Hall of the Two Hundred of the Palazzo Vecchio (Old Palace)) in Florence. In this paper an appropriate transient 3D model by Computational Fluid Dynamics (CFD) software based on the finite element method (FEM) was used. Variations and interaction between indoor and outdoor microclimatic conditions, and thermo-physical behaviour of the building connected to lighting, visitor presence and cooling–heating fan coils system were considered. The 3D modelling method provided by the present paper can be applied to several situations where there is interaction between outdoor and indoor climate variations and the building structure. It can be very useful for defining measures to preserve tapestries, understanding deterioration processes, and developing new conservation techniques and strategies for care and exhibition.     

Decay regions segmentation from color images of ancient monuments using fast marching method

This work faces the problem of detecting decay zones from color images of stone materials. In Cultural Heritage, the extraction of degradation regions from images of ancient monuments represents an important step forward in studying and analyzing the state of preservation of historical buildings. Generally the decay diagnosis is provided by “naked eye” analysis done by expert scientists “walking around” the artifact and recording the conservation state of each individual element they observe. In addition to this kind of investigation, the application of an image segmentation strategy to color images of stony materials can be used in order to extract regions characterized by a visible chromatic alteration, changes in color, for example, as oxidation or concretion. This paper features a color image segmentation approach founded on the fast marching numerical method. We have applied this technique for its possibility to work locally, that is, only the contour of the region under study is processed. In addition to this method, we present a global approach, that is, the possibility to extract decay regions from the entire image; these regions are spatially disconnected but with similar colorimeter value. The main aim of the present work is to provide a tool that helps the expert to contour the degraded regions. In this sense even if the results of the proposed procedure depend on the expert evaluation, the approach can be a contribution to improve the efficiency of the boundary detection process. The study case concerns the impressive remains of the Roman Theatre in the city of Aosta (Italy). In the image segmentation process the color space L*a*b* is utilized.     

A practical approach to making accurate 3D layouts of interesting cultural heritage sites through digital models

On many occasions, the graphic information handled by people working in the cultural heritage sector is still bidimensional. Layouts showing elevations and cross sections are the most widespread tools. However, there is an increased need for carefully detailing the complexity of valuable sites with an improved accuracy. This implies the measuring and handling of three-dimensional data, using both commercial and turn-key hardware and software solutions. Taking the usual traditional process as a reference, in the present paper a new effective methodology for carrying out computer assisted delineation of layouts from cultural heritage sites, using 3D digital models, is described. The proposed procedure has been tested in five intervention projects on representative churches within the “Merindad de Aguilar de Campoo” medieval area, in the north of Spain.¹ This area has the largest collection of Romanesque art in the world, and is currently under European Heritage Site and World Heritage Site declaration process by the UNESCO.     

Effects of wax-based anti-graffiti on copper patina composition and dissolution during four years of outdoor urban exposure

The protection against graffiti has become a serious problem in most cities. Unfortunately such form of vandalism does not save the cultural heritage. The use of anti-graffiti coatings is a common treatment that can also temporary protect the surface from degradation due to interactions with the environment. Aspects that have not yet been sufficiently investigated from a metal artefact perspective are whether the presence of the anti-graffiti coating will influence the patina composition and reduce the degree of patina dissolution. Long-term (four years) effects of wax-based anti-graffiti coatings on bare copper sheet and pre-patinated copper exposed to urban atmospheric conditions are presented and discussed in terms of changes in patina dissolution rates, barrier properties and composition. The investigation is based on a multi-analytical approach combining chemical analysis, analytical and electrochemical tools (stereomicroscopy, FTIR, XRD, SEM/EDS, AAS, EIS, colorimetric measurements). Results are believed to provide important information related to the long-term applicability of such coatings to preserve the Cultural Heritage.     

Integrity in UNESCO World Heritage Sites. A comparative study for rural landscapes

Since 2005, Outstanding Universal Value (OUV) is the standard by which United Nations Educational Scientific and Cultural Organization (UNESCO) evaluates world cultural heritage site suitability. The sites worthy of UNESCO preservation as well as the parameters used to demonstrate OUV are diverse. Our study focused on the uniquely distinguished rural landscape sites and the OUV parameter of integrity. Integrity however, is an elusive concept for which UNESCO provides no definitional protocol, and for which the scientific community objects to a static or pure historical interpretation. Given this, our work aims to analyse the concept of integrity and how it can be used to preserve the heritage of rural landscapes. After reviewing the UNESCO approach, we focused on the international scientific debate on the meaning and application of integrity. We designed and conducted a comparative study of UNESCO rural landscapes selected from the 2011 World Heritage List. Documents describing the historical, rural, and agro-ecological features of each of the fourteen rural sites were analysed. From this, several historical and ecological parameters were chosen as “values to have” and several socio-economic and management parameters were chosen as “values to maintain” to assess the integrity of each landscape. Our results found integrity to be a value of both cultural and natural landscapes and that it is key to site identity. We demonstrated that UNESCO assigns a high value to the following parameters: historical features, traditional crops and local products, land-use and agricultural practice permanence, and the presence of architecture related to agricultural activity. Finally, we found the relationship between culture and nature to characterize best the integrity of a rural landscape, rather than nature or culture alone.     

Cartographic heritage: Toward unconventional methods for quantitative analysis of pre-geodetic maps

Historical cartography all over the world is a fundamental part of Cultural Heritage, and it needs to be preserved from damage of its analogical support due to ageing. Regeneration of ancient cartography in digital form is an interesting way not only to preserve historical cartographic documents as Cultural Heritage, but also to allow new chances of understanding and using the historical information they record. In such a way, modern digital techniques, in particular study of map deformations and map georeferencing, help in metric analysis of ancient cartography, and at last they appear to be useful for researchers to derive historical information for their studies, for example related to urban development or to geomorphological and environmental topics. The present research would give an example of the usefulness of the digital regeneration of ancient cartography, but also an example of possible difficulties in correctly interpreting information preserved in historical cartography, especially the pre-geodetic one. The study subject consists in three contemporaneous pre-geodetic maps (late 16th century) from the ancient Po river delta area (Italy), by means of which a geometrically correct representation of those parts of the landscape, not preserved today because of sea erosion, was tried. In fact, standard georeferencing methods, that use reference control points to compare historical cartography with the present one, in this specific case demonstrated to be not successful in describing the real location of disappeared landscape details with an adequate level of accuracy. For these reasons, in order to define which map among the others was the most faithful to the contemporaneous physical reality, a compound methodology, consisting of a three-step analytical process, is here applied to the three samples. Starting from measurement of sighting angles and distances applied to a number of landmarks, a splitting of the old maps in sub-areas, probably corresponding to the set of original surveyed zones, was performed. In the area of main concern, the use of absolute measurements was avoided in order to check the level of inner congruence of the representation. Finally, a new specific error index, that can also be applied to maps lacking an explicit graphical scale, is proposed to evaluate the map truthfulness degree. The proposed method can be applied to other similar examples from ancient cartography.     

Multispectral data cube acquisition of aligned images for document analysis by means of a filter-wheel camera provided with focus control

Multispectral imaging techniques are widely used to analyse and restore digital images of ancient documents degraded over time. In particular, acquisitions in infrared and ultraviolet bands can reveal information invisible by naked eye, which is not captured by conventional RGB imaging. Multispectral acquisitions are usually performed with filter-wheel cameras that mount a series of interference filters in front of the sensor to select the spectral band in which the document has to be acquired. Due to the use of different filters, the focus of the lens changes and it is necessary to adjust it manually for each filter, because such imaging systems are devoid of automatic focusing. Thus the acquired images may not be perfectly in-focus and have misalignments. In this work we present an automatic solution to acquire a multispectral data cube of aligned images that can be used in document analysis to extract and/or separate information through enhancement techniques. A custom-made motorized autofocus system controlled by software has been installed on a filter-wheel camera, which allows us to acquire in-focus images automatically at each filter changing, and a registration method based on Fourier-Mellin transform aligns these images. A preliminary calibration is performed to set the focusing of each filter with the working distance. As a result, the camera can capture images independently from the contrast of the scene, also in presence of documents with homogeneous texture. The proposed solution reduces considerably the acquisition time and offers a tool to acquire automatically the data cube to be used in further image analysis techniques. The results of experimentations are hereby presented and discussed.     

Smart surfaces for architectural heritage: Preliminary results about the application of TiO2-based coatings on travertine

The development and application of self-cleaning treatments on historical and architectural stone surfaces could be a significant improvement in conservation, protection and maintenance of Cultural Heritage. In this paper, a TiO₂-based coating has been investigated in order to evaluate its possible use as a self-cleaning treatment. This coating was obtained by a sol-gel and a hydrothermal (134 °C) processes and then it was applied on travertine (a limestone often used in historical and monumental buildings) in two ways, obtaining a single-layer and a three-layer treatment, respectively. In order to verify its potential use in the field of Cultural Heritage, the maintenance of appearance properties of the treated travertine surfaces was monitored by colour and gloss analyses. Besides, de-pollution and soiling removal tests were carried out under ultraviolet-light exposure to evaluate photo-induced effects and self-cleaning efficiency. Results seem to allow the use of TiO₂-based treatments on historical and architectural surfaces made up by travertine, where de-pollution and self-cleaning photo-induced effects are well evident, maintaining their original visual appearance. Anyway, before applying TiO₂-based coatings as conservative treatments, further tests are needed especially on their durability, that is mandatory for Cultural Heritage applications. On-site test in an urban environment and accelerated test by weatherometer are currently under way.     

Methods for 3D digitization of Cultural Heritage

Complete digital recording of Cultural Heritage is a multidimensional process. It depends highly on the nature of the subject of recording as well as the purpose of its recording. The whole process involves the three-dimensional digitization, digital data processing and storage, archival and management, representation and reproduction. In this paper we briefly review methods for three-dimensional digitization that are applicable to cultural heritage recording.     

Digital preservation of Brazilian indigenous artworks: Generating high quality textures for 3D models

Three-dimensional (3D) digital preservation aims at generating 3D models of objects that have cultural or scientific value. It allows realistic visualization of objects through virtual museums or scientific applications, and the restoration of the preserved object in case of natural wear or accidents. This work contributes to this research area by presenting a method to improve color texture quality of 3D models obtained from color and depth images of a laser scanner. Although this device offers precise depth information, the resulting color information is still poor and limits the generation of realistic textures. Our approach is to capture photographs of the object with a high-resolution digital camera and use them to generate a new color texture for the 3D model. Our work proposes a practical technique, easy to replicate, to generate high quality textures for 3D models from photographs. The method is composed by three main steps: (1) calibration of the image acquisition devices; (2) data acquisition; and (3) texture generation. In this paper, we detail our color texture generation method and apply it on the digital preservation of many artworks made by native Brazilians (indians) from the Wauja and Karaja communities. These indigenous communities are acknowledged as great ceramic artists, each bearing their own main themes, using a very rich symbolism in their paintings. Their artworks represent important aspects of the native South American culture and their digital preservation is motivated by three main reasons: (1) their fragility; (2) the paintings loose their original appearance with time; and (3) the possibility of extinction of these communities. We present several results of preserved artworks with enhanced quality realistic texture maps. Also, we present a methodology to analyze the quality and accuracy of texture maps. The resulting 3D models can be visualized through a tool we developed to support the virtual exhibit of 3D preserved heritage.     

西湖申遗彰显文化魅力——本刊记者访西湖申遗专家组组长陈文锦

记者：陈老师,今天想请你谈谈杭州西湖申遗的事. 答：我作为一个了解西湖历史和文化的过来人,主要是思考者的角色,所以,下述谈话内容,也只能是我个人的观点。     

Approach to environmental risk analysis for the main monuments in a historical city

The analysis of environmental risk in historical cities facilitates the development of conservation strategies that can minimize the deterioration of historical heritage sites. Risk maps built with GIS software provide information about the probability of the main hazards in a region, and is a very useful tool to identify, evaluate and prioritize the restoration budget of a city in order to manage preventive conservation. In this paper, new methodologies are applied based on the vulnerability matrix and its relationship with static and structural factors, climate conditions, air quality and social agents. This technique has some obvious advantages in the application of risk analysis for cultural heritage conservation, such as the capability of simultaneous risk assessment and geographical references. The vulnerability study implies an on-site diagnosis analysis and requires an adapted protocol for archaeological heritage. The validation of this methodology was carried out in the historical town of Merida (Spain) with a GIS application (ArcGIS software), where the main monuments of this UNESCO World Heritage site were studied.