3D digitizing of cultural heritage

In this paper, the authors briefly review the state of the art of the 3D acquisition and digitizing techniques applied to heritage. The main focus is on motivations, issues and technical specification of the 3D digitizing of heritage artworks. Different digitizing technologies currently available for this specific application have been evaluated and tested, with application to a pair of case studies, showing that 3D digitizing technologies are sufficiently developed for extensive application in the field of cultural heritage.     

Automated camera network design for 3D modeling of cultural heritage objects

Image-based modeling is an appropriate technique to create 3D models of cultural heritage objects, which starts with the basic task of designing the camera network. This task is, however, quite crucial in practical applications because it needs a thorough planning and a certain level of experience. The optimal camera network is designed when certain accuracy demands are fulfilled with a reasonable effort, namely keeping the number of camera shots at a minimum. In this study, we report on the development of an automated method for designing the optimal camera network for a given cultural heritage building or statue. Starting from a rough point cloud derived from a video image stream, the initial configuration of the camera network is designed, assuming a high-resolution HR state-of-the-art non-metric camera. To improve the image coverage and accuracy, we use a mathematical non-linear optimization with constraints. Furthermore, synthetic images are created to guide the camera operator to the designed images. From the first experimental test, we found that a target accuracy of 10 mm could be maintained although the initial number of more than 300 high-resolution images got reduced to less than 90 for the final, optimized network.     

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.     

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.     

Efficiently capturing large,complex cultural heritage sites with a handheld mobile 3D laser mapping system

Accurate three-dimensional representations of cultural heritage sites are highly valuable for scientific study, conservation, and educational purposes. In addition to their use for archival purposes, 3D models enable efficient and precise measurement of relevant natural and architectural features. Many cultural heritage sites are large and complex, consisting of multiple structures spatially distributed over tens of thousands of square metres. The process of effectively digitising such geometrically complex locations requires measurements to be acquired from a variety of viewpoints. While several technologies exist for capturing the 3D structure of objects and environments, none are ideally suited to complex, large-scale sites, mainly due to their limited coverage or acquisition efficiency. We explore the use of a recently developed handheld mobile mapping system called Zebedee in cultural heritage applications. The Zebedee system is capable of efficiently mapping an environment in three dimensions by continually acquiring data as an operator holding the device traverses through the site. The system was deployed at the former Peel Island Lazaret, a culturally significant site in Queensland, Australia, consisting of dozens of buildings of various sizes spread across an area of approximately 400 × 250 m. With the Zebedee system, the site was scanned in half a day, and a detailed 3D point cloud model (with over 520 million points) was generated from the 3.6 hours of acquired data in 2.6 hours. We present results demonstrating that Zebedee was able to accurately capture both site context and building detail comparable in accuracy to manual measurement techniques, and at a greatly increased level of efficiency and scope. The scan allowed us to record derelict buildings that previously could not be measured because of the scale and complexity of the site. The resulting 3D model captures both interior and exterior features of buildings, including structure, materials, and the contents of rooms.     

A definition of cultural heritage: From the tangible to the intangible

The aim of this work is to analyse the evolution of the concept of cultural heritage in West European states. In the last decades of the 20th century, the term “heritage” was characterised by expansion and semantic transfer, resulting in a generalisation of the use of this word, frequently used in the place of another, such as, monument and cultural property. However, all these terms are not able to cover the same semantic field. Starting by the reflection on the semantic evolution of the notion of cultural heritage in France, we approach to the international definition of heritage given by the directives, charters and international resolutions in order to define a global outline of the meaning of heritage that is not just limited to a particular national dimension. From a purely normative approach, one went to a less restrictive approach, one based on the capacity of the object to arouse certain values that led the society in question to consider it as heritage and therefore, to a further step in which heritage is no longer defined on the basis of its material aspect. This development has also made it possible to recognise intangible cultural heritage, which was ignored for a long time, as heritage to be protected and safeguarded.     

Multi-image 3D reconstruction data evaluation

A number of software solutions based on the Structure-From-Motion (SFM) and Dense Multi-View 3D Reconstruction (DMVR) algorithms have been made recently available. They allow the production of high quality 3D models by using unordered image collections that depict a scene or an object from different viewpoints. In this work, we question the quality of the data produced by a commercial SFM-DMVR software. An Ottoman monument located in the region of Xanthi, Greece has been selected as a case study. We attempted to quantify the quality of the SFM-DMVR data in relation to the data produced by a Time-of-Flight terrestrial 3D range scanner. We have implemented a number of comparisons between different parts of the monument in order to assess the mesh deviations and the reconstruction's accuracy. In order to further ensure the validity of our evaluation phase, we performed additional distance measurements between feature points on the monument's surface by using a total station and empirical measurements. The applicability of the SFM-DMVR method was questioned by creating a complete 3D digital replica of the monument.     

Documentation of cultural heritage using digital photogrammetry and laser scanning

Precise documentation of cultural heritage status is essential for its protection and scientific studies carried out during the restoration and renovation process. The close range photogrammetry has been used successfully for documentation of cultural heritage. With recent developments in computer and information technologies, this well-known traditional method has been replaced with digital close-range photogrammetry. This new method offers us new opportunities such as automatic orientation and measurement procedures, generation of 3D vector data, digital ortho-image and digital surface model. Terrestrial laser scanning is another technology that in recent years has become increasingly popular for documentation which provides very dense 3D points on an object surface with high accuracy. In addition, the 3D model and digital ortho-image can be easily generated using generated 3D point cloud and recorded digital images.     

Using contingent valuation and cost-benefit analysis to design a policy for restoring cultural heritage

Historical heritage is proving an ideal field to apply contingent valuation for estimating individual as well as collective preferences as goods tend to be non-market and publicly owned. Yet despite this, findings are seldom used to draw up cultural policies or assess cultural heritage related projects. The current paper thus posits an approach which merges contingent valuation and cost-benefit analysis to design a cultural policy aimed at restoring the urban cultural heritage of the city of Valdivia (Chile). Contingent valuation is used to estimate the expected benefits from heritage for both local residents and tourists visiting Valdivia. We then apply cost-benefit analysis to the findings to evaluate a project to restore the historical ensemble through a non-profit foundation. The originality of the proposal lies in its merging the two approaches and may prove appealing to developing countries in which much of the heritage has been neglected and left to deteriorate, and where few or no resources have been devoted and a lack of effective institutional schemes to address the situation is evident.     

Process for the 3D virtual reconstruction of a microcultural heritage artifact obtained by synchrotron radiation CT technology using open source and free software

Computer tomography (CT) technology has greatly contributed to the feasibility and convenience of detecting and visualizing the internal material constitution and geometrical fabrication of museum artifacts. This paper presents a case study of 3D virtual reconstruction for the CT-acquisition-based study of a cultural heritage artifact. It documents the complete procedure, including the preprocessing, segmentation and visualization of the data by providing coarse interactive exploration and integrated high-quality renderings. A parallel aim achieved was to use open source tools and free software for segmentation and visualization, thus providing full transparency of the adopted methodology and 3D visualization methods, and a cost effective solution for ordinary CPU-based PC users. Furthermore, the challenges of the large data volumes involved have been addressed using preprocessing, a segmentation scheme and linked front-to-back management to keep interaction and high-quality rendering available, thus achieving corresponding demands.     

Designing interaction metaphors for Web3D cultural dissemination

In the last few years the improved performances of graphics hardware and the growing availability of broadband internet connections have eventually led to effectively adding a third dimension to web interfaces, achieving what is commonly referred to as Web3D. Nevertheless, these technologies are not yet widespread, especially in the cultural sector, for at least two factors: technological limitations, mostly in the lack of coherent and effective metaphors to visualize and interact with digital cultural assets using the third-dimension as an added value rather than as a stylish gadget, and communication issues, as, despite the principles stated in the London Charter aimed at ensuring technical and intellectual rigor for the digital visualization of cultural heritage, a proper way to deal with relevant and sustainable 3D information is not yet completely established. For this reason this paper focuses on identifying and analyzing the aspects that may contribute to a more efficient use of Web3D technologies to access cultural content, in order to set up a set of development standards aiming to encourage web-based learning and guaranteeing systems accessible and usable by the widest possible audience.     

Web technologies applied to virtual heritage: An example of an Iberian Art Museum

Nowadays, some virtual museums include 3D room scenes to show the models of its pieces, just like in real museums. Nevertheless, the generation and maintenance of this kind of scenes is generally difficult and should be done by an expert. For example, any change such as including a new piece or modifying the position of an existing fragment usually requires a different design and the creation of a new scene. In this paper we present a case study on the development of a web-based application to automatize this process. To this end, a database to store both graphic and non-graphic information about the pieces, and some 3D rooms to show them has been created. The designed scenes only contain some pieces of furniture to exhibit the fragments, which will be subsequently included. Thus, when a room is loaded in the web page, its associated pieces are obtained through a query in the database and its models are dynamically included in the original scene. Therefore, the position changes or the inclusion of new pieces are not performed in the 3D model, but in the database. Our application makes the transmission of the knowledge to the general public easier because any new discovered piece can be included in a existing museum effortlessly.     

Copyright and IPR management for cultural heritage digital content in peer-to-peer networks

As a general and effective protection measure for copyright violations, which occur with the use of digital technologies including peer-to-peer (P2P) networks, copyright owners from the cultural sector often use Digital Rights Management (DRM) systems and digital watermarking techniques so as to encrypt copyright information to the cultural content. In other cases, copyright owners restrict or even block access to the digital cultural content through the Internet and the P2P infrastructure. This chapter claims that DRM and P2P can be quite complementary. Specifically, a P2P infrastructure is presented which allows broad digital cultural content exchange while on the same time supports copyright protection and management through watermarking technologies for digital images.     

Combining the travel cost and contingent behavior methods to value cultural heritage sites: Evidence from Armenia

This paper combines the travel cost method (TCM) with contingent behavior questions to estimate domestic visitors’ use values for cultural heritage sites in Armenia, a transition economy in which conservation of cultural monuments is hampered by limited resources. Respondents intercepted at four cultural monuments provided information on their visitation patterns, experience at the site, perception of the state of conservation of the monuments, and rating of the quality of the services and infrastructure. We combine actual trips with stated trips under hypothetical programs that would enhance the conservation of the monuments and improve one of (i) the cultural experience at the site, (ii) the quality of the infrastructure, or (iii) the quality of the services, and use the combined actual and stated trips to fit a panel data model. Our study is one of the few applications of the TCM to value cultural heritage sites. Our investigation shows that (i) significant use values are associated with the four study monuments, and (ii) conservation programs and initiatives that improve the cultural experience, or simply make it easier for the respondent to reach and spend time at the monument, are valued by domestic visitors and would encourage higher visitation rates. Actual and intended trips reported by the respondents exhibit good construct validity, in the sense that they are well predicted by price, location, hypothetical scenario and other individual characteristics of the respondents.

走读英国文化遗产保护利用模式

正2016年10月9日至29日,应英国东伦敦大学邀请,浙江省文物局组团"文化遗产保护与利用"项目,由浙江省文化厅副厅长陈瑶带领18位来自浙江省、市、县文博单位的专业及管理人员赴英国进行了为期21天的培训。此次培训采取授课讲座、座谈交流和实地考察等形式进行,培训地点包括大学、世界遗产、文物建筑保护管理机构、博物馆等。培训内容围绕《英国文     

Cultural heritage interactive 3D models on the web: An approach using open source and free software

Cultural heritage sites and artefacts get a significant added value from high-resolution 3D models. These models are increasingly available due to improvements in technology and to higher integration of survey techniques such as laser scanning and photogrammetry. In this paper we present a case study on the development of a web-based application for user access and interactive exploration of three-dimensional models by providing integrated geometrical and non-geometrical information into an intuitive interface. The main feature of this interactive system is to provide the user with a completely new visit experience based on a free interactive exploration interface of the object (i.e., not constrained by any predefined pathway) and on the opportunity to get more detailed information on specific parts of interest. A parallel aim achieved was to use, in data processing and in the architecture, open source tools and free software, thus providing full transparency on adopted methodology and data processing methods, and a cost effective solution both for server and client. Furthermore, the aspect of data size has been considered using a segmentation and simplification scheme and server-side data management to keep transmission size to a minimum, thus improving access speed.     

Analysing the possible impact of landslides and avalanches on cultural heritage in Upper Svaneti,Georgia

In this paper, the threat posed to cultural heritage by landslides and avalanches is analysed for two communities (Ushguli and Mulakhi) in the Upper Svaneti region in Georgia. The vulnerability of 60 cultural heritage objects has been evaluated through a conservation calculation based on an existing methodology using a State of Conservation Index (SCIx), which served as an input in a Spatial Multicriteria Evaluation (SMCE). Factors that are considered important for the occurrence of landslides (slope, landcover, lithology and drainage density) and snow avalanches (slope, insolation, slope curvature and landcover) have been used to generate a susceptibility map. A qualitative risk assessment was carried out by combining susceptible areas and cultural heritage objects. As there were very limited historical data available on the occurrence of landslides and snow avalanches, a combination of local and expert knowledge has been used to extract information on both cultural heritage and natural hazards. Existing management plans were also analysed to evaluate how natural hazards could be incorporated. Finally, some recommendations are given related to the analysis of the impact of natural hazards on cultural heritage in Georgia.     

Definition of the procedure to determine the suitability and durability of an anti-graffiti product for application on cultural heritage porous materials

Anti-graffiti protection is becoming a common practice in many urban buildings, especially in areas of social decay. When Cultural Heritage objects are affected by graffiti, the application of anti-graffiti products can result not only in an unsatisfactory result but also in an irreversible damage of an invaluable cost. The materials commonly found in these constructions are very frequently porous and present different types of decay forms. For this reason, the protection of these materials should be carefully considered. This paper proposes a criterion to decide on the suitability and durability of an anti-graffiti product prior to its application in a porous surface of a protected building. Performance classifications are defined for a series of properties including colour and gloss, and hydric and durability properties, and minimum acceptable values or reductions in these properties are recommended.     

Trees as natural barriers against heavy metal pollution and their role in the protection of cultural heritage

Leaves of common deciduous trees: the horse chestnut (Aesculus hippocastanum) and linden (Tilia spp.) from the park, near one of the most important cultural institutions, the National Library of Serbia, were studied as bioaccumulators of heavy metal (Cr, Fe, Ni, Zn, Pb, Cu, V, As and Cd) air pollution. The leaf samples were collected from the urban park exposed to the exhaust of heavy traffic. The May–September heavy metal accumulation in the leaves, and their temporal trends, were assayed in a multi-year period (2002–2006). Comparing the obtained concentration of the investigated elements from the beginning to the end of growing seasons, a significant rate of accumulation was determined for a majority of measured elements, and it was concluded that these tree species (horse chestnut and linden) can be used as bioaccumulators of the investigated heavy metals. The SEM-EDAX analysis of individual particles deposited on the leaves showed that the 50–60% belong to a class of fine particles (D < 2 μm), mainly of anthropogenic origin. Thus, the investigated tree species could be grown as a natural barrier against urban air pollution in the vicinity of libraries, museums and other buildings for cultural heritage storage.