Methodological approaches for the protection of cultural heritage in the digital age

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Thesis

Reference

Methodological approaches for the protection of cultural heritage in the digital age

FONI, Alessandro

Abstract

Les perspectives offertes par les représentations digitales 3D dans les domaines liés à la protection de l'héritage culturel posent des questions d'ordre méthodologique concernant le type de média et les technologies qui peuvent être utilisées afin d'obtenir un résultat qui soit satisfaisant pour tous ceux qui oeuvrent dans ces secteurs. De ce fait, l'objectif principal de ce travail est celui d'identifier les éléments que ces différents acteurs considèrent essentiels pour qu'un projet de visualisation puisse satisfaire aux exigences et aux défis qui caractérisent leurs secteurs d'activité. Notre étude déterminera quelles approches, quelles stratégies de création de contenu et quelles technologies chacun de ces groupes perçoit comme étant les plus adaptées afin de répondre à leur besoins respectifs. Cette analyse posera également les fondements conceptuels nécessaires à la définition d'un ensemble d'éléments convergents et de traits communs qui caractérisent les préférences de ces acteurs : ces convergences pourront être exploitées afin de proposer des représentations polyvalentes qui [...]

FONI, Alessandro. Methodological approaches for the protection of cultural heritage in the digital age . Thèse de doctorat : Univ. Genève, 2013, no. SES 826

URN : urn:nbn:ch:unige-323837

DOI : 10.13097/archive-ouverte/unige:32383

Available at:

http://archive-ouverte.unige.ch/unige:32383

Disclaimer: layout of this document may differ from the published version.

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approaches for the protection of cultural heritage in the digital age

THÈSE

présentée à la Faculté des sciences économiques et sociales de l’Université de Genève

par

Alessandro Foni

sous la direction de

prof. Nadia Magnenat-Thalmann

pour l’obtention du grade de

Docteur ès sciences économiques et sociales mention systèmes d’information

Membres du jury de thèse:

Mme. Nadia MAGNENAT-THALMANN, Professeur M. Dimitri KONSTANTAS, Professeur, président du jury

M. Jean-Henry MORIN, Professeur

M. George PAPAGIANNAKIS, Professeur, Université de Crète

Thèse no 826

Genève, 2 décembre 2013

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La Faculté des sciences économiques et sociales, sur préavis du jury, a autorisé l’impression de la présente thèse, sans entendre, par là, n’émettre aucune opinion sur les propositions qui s’y trouvent énoncées et qui n’engagent que la responsabilité de leur auteur.

Genève, le 2 décembre 2013

Le doyen

Bernard MORARD

Impression d'après le manuscrit de l'auteur

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Résumé

L’utilisation de représentations graphiques, usuellement sous forme de dessins ou perspectives en deux dimensions, constitue une de premières tentatives pour mieux conserver, diffuser et disséminer la documentation relative aux découvertes archéologiques et de manière générale concernant les sites d’héritage culturel [OGLEBY01]. La création manuelle de restitutions détaillées constitue un support précieux qui permet une meilleure compréhension du contexte de l’époque à laquelle un site a été bâti. De plus, ces méthodes de représentation offrent la possibilité d’expérimenter graphiquement et de transmettre des hypothèses spécifiques [SANDERS99] concernant l’apparence originale supposée d’un site donné. Cela permet donc à la fois de répondre au besoin de documentation du site et, en même temps, crée un support pour l’interprétation des découvertes.

La démocratisation des technologies de l’information, l’arrivée récente sur le marché de cartes vidéo GPU à haute performance et la disponibilité de CPU rapides à bas couts, ainsi que les avancées récentes dans le domaine de l’

infographie 3D, ont permis l’essor de nouvelles méthodes de représentation, d’analyse, de conservation et de divulgation de la documentation relative aux sites d’héritage culturel. Ces techniques offrent des nouveaux supports pour effectuer des études de restitution afin de tester des hypothèses, ainsi que la possibilité de toucher un public plus large [MILLER94] [FORTE97].

Bien que plusieurs projets se basant sur différentes technologies et approches, et visant la réalisation de représentations virtuelles de sites d’héritage culturel, aient été réalisées, il n’a pas été possible d’identifier une méthodologie qui réponde aux attentes et besoins de plusieurs groupes ciblés. Cela a souvent limité l’utilité de ces travaux à un seul groupe spécifique d’utilisateurs finaux. Par exemple, si d’un côté les reconstructions adressées au public général, telles que les films générés par ordinateur, ne sont que rarement considérées favorablement par les archéologues, de l’autre côté les reconstructions qui visent en premier les historiens et les archéologues ne sont souvent pas d’accès facile pour le grand public [SIDERIS02].

Cependant, les perspectives offertes par les représentations digitales 3D dans le domaine de l’archéologie et de la conservation de l’héritage culturel [REILLY92]

posent certaines questions d’ordre méthodologique concernant la forme optimale, le type de média, l’approche appropriée et les technologies à utiliser pour obtenir une restitution qui soit satisfaisante à la fois pour les besoins de documentation du conservateur, pour les besoins d’interprétation de l’historien ainsi que pour les attentes de haut réalisme visuel du public [ADDISON00].

Par conséquent, un des principaux objectifs de ce travail est celui d’identifier les éléments essentiels pour les différents groupes actifs dans le domaine de la protection de l’héritage culturel et sur lesquels ceux-ci basent leurs décisions de considérer un type de visualisation comme réussie. Par ailleurs, on essayera également de déterminer quelles approches et technologies chacun de ces acteurs perçoit comme étant les plus adaptées afin de répondre à leur besoins et nécessités.

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Ainsi, cette étude essayera d’établir les bases conceptuelles nécessaires à l’identification de lignes directrices méthodologiques claires et de pratiques adaptés qui puissent correspondre aux spécificités des groupes d’utilisateurs finaux. Ces lignes directrices, si appliquées, devraient permettre une amélioration de l’efficacité, de l’utilité et de l’impact de futurs projets reliés à l’héritage culturel virtuel, puisqu’elles devraient faciliter la mise en place de cycles de prototypage plus courts. En effet, la quantité de travail requise pour produire une représentation virtuelle qui réponde aux attentes et aux besoins d’un groupe d’utilisateur final donné en serait ainsi optimisée.

De plus, la possibilité d’employer un ensemble d’éléments convergents et de traits communs, dans le but de créer une représentation virtuelle polyvalente prévue pour plusieurs groupes d’utilisateurs finaux, sera explorée afin de permettre l’identification d’une approche méthodologique équilibrée et généralisée qui puisse répondre simultanément aux besoins de tous les acteurs ciblés.

La détermination à la fois d’une stratégie de visualisation, et d’une approche de création de contenu, qui pourraient offrir à ces acteurs un compromis acceptable par rapport à leurs préférences, serait un atout de taille. Notamment, cela éviterait d’avoir à créer plusieurs versions d’une même application d’héritage culturel et permettrait ainsi d’économiser en amont le temps qui actuellement est dédié à une procédure de recherche par tâtonnement du média et de la forme plus appropriés pour répondre aux demandes de différents groupes d’utilisateurs finaux ciblées par chaque nouveau projet entrepris dans ces domaines.

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Abstract

The use of graphical representations, usually in the form of two dimensional drawings or perspectives, constitutes one of the first attempts to better preserve, extend and divulgate the documentation that pertains to archeological, and more generally, cultural heritage sites [OGLEBY01]. Detailed hand-made restitutions represent a precious support which allows for a better understanding of the time dependant context in which a selected site was built. Furthermore, such visualizations offer the possibility to graphically experiment and easily convey specific hypothesis [SANDERS99] regarding the supposed past appearance of a given site, thus satisfying both the need to offer an accessible way to document a site and to offer a support for the interpretation of any finding.

The democratization of information related technologies, the recent advent of low cost, high-performance GPU based video cards, the availability of affordable and fast CPUs, as well as the recent advances in the field of 3D graphics have opened new ways and forms to present, analyze, preserve and divulgate the documentation linked to cultural heritage sites. Such modern technologies have offered new supports for the creation of restitution studies for the purpose of hypothesis testing, as well as they have provided the possibility to reach a broader audience [MILLER94] [FORTE97].

Even though several projects that rely on different technologies and approaches, aiming at the creation of virtual representations of heritage sites, have been developed in the past years, no clear methodology has been identified in order to achieve an optimal balance between the expectations and the needs of the all the groups that could have been targeted by those reconstructions, thus limiting the benefit of such work only to one specific group of end users. For instance, the reconstructions that are targeting the general public through computer generated movies rarely encounter the appraisal of archeologists, while on the other hand, restitutions that target primarily archeologists and historians appear often less accessible for the general public [SIDERIS02].

However, the perspectives offered by the use of 3D digital representations in the field of archeological and heritage preservation [REILLY92] raise some methodological issues as well as some fundamental questions regarding the optimal form, the type of media, the correct approach and the technologies that are to be deployed in order to achieve a restitution that could satisfy both the preservationist’s need for documentation, the historian’s need for interpretation and the public’s expectations for high visual realism [ADDISON00].

As such, one of the main purposes of this work is to identify the primary elements that each of the groups that are active in the field of cultural heritage protection regards as being the most important, and upon which it bases its decision to consider a proposed visualization as a successful one or not.

Moreover, we equally seek to determine which approaches and technologies each of those actors perceives as being the most appropriate to satisfy their needs and requirements. As a result, our study will attempt to establish the necessary conceptual bases to allow the identification of clear and practical methodological guidelines that match the specificities of the considered end user groups. Such guidelines, if implemented, should then permit an improvement of

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the effectiveness, usefulness, and impact of future projects related to virtual cultural heritage, as they should allow for shorter prototyping cycles, since the amount of work required to produce a virtual representation matching both the expectations and the needs of a given user group will be optimized.

Additionally, the possibility to employ a set of converging elements and common traits to enable the successful constitution of a multi-purpose virtual representation intended for multiple end-user groups will be explored to allow the identification of a balanced and generalized methodological approach that could simultaneously meet the needs of each targeted actor.

The determination of a visualization strategy and a content creation approach that could offer such actors an acceptable trade-off regarding their preferences should prove to be a valuable asset to eliminate the necessity to prepare, through a trial and error process, several different virtual heritage applications, on different medias and under different forms, in order to meet the requirement of different end-user groups.

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Acknowledgements

First of all, I would like to take this opportunity to express my gratitude to Professor Nadia Magnenat-Thalmann for the guidance, the support and the encouragement she continuously provided, as well as for having offered me the privilege to join a gifted and multidisciplinary group such as MIRALab. Her unique perspective as well as her novel ideas supported and inspired me all the while.

I equally wish to extend my gratefulness to all the members of the jury, to Professor Dimitri Konstantas and Dr. George Papagiannakis as well as to Dr.

Jean-Henry Morin, Dr. Laurent Moccozet and Amal Tawfik: their expert advice, their help, as well as their sharp comments and feedback have been an invaluable source of incentive and motivation.

Moreover, I gratefully acknowledge the funding received from the INCO-MED FP5 European Project ERATO (2006) as well as the funding received from the Swiss Virtual Campus projects CATCH and Understanding 3D (2008): they supported preliminary research on some of the topics discussed in this manuscript as well as the creation of most of the 3D models that have been used to produce the renderings included in the questionnaires that have been employed during the data gathering process.

Furthermore, I desire to express my thanks to Professor Jean-Paul Descoeudres (University of Geneva), Professor Pierre Sánchez (University of Geneva) as well as to Marc-Andre Haldimann (head of the Geneva museum of archaeology) who preciously contributed to this work by kindly accepting to share their experience and their opinion concerning the themes discussed in the frame of this work. For the same reasons, special thanks are equally due to Cristina Dalla Valle, Marco Fontanini, Dr. Michel Pawlak, Agostino Giaffreda, Massimo Soldini, Nedjma Cadi-Yazli, as well as to Cpt. Roberto Piantoni and the personnel dedicated to the protection of cultural heritage serving in the Civil Protection of the Region of Lugano.

Amid both the former and the current members of MIRALab and the CUI, many have helped and supported me through the years on countless occasions and in ways far too diverse to be fully described: suffice to say that their talents, trust, dedication and friendship have greatly contributed to render the time I spent among them an interesting and exciting period of my life filled with exhilaration and enthusiasm. More particularly, I am very grateful to Marlène Arevalo-Poizat, Nabil Sidi-Yacoub and Jean-Claude Moussaly, which have been my mentors before becoming my colleagues and friends. Their guidance, passion and constant encouragement have significantly and positively influenced my academic choices: without them, my latent interest for computer graphics would probably have remained just a hobby.

Additionally, I would like thank Camillo Tanzi, Angela Macciocchi and Anna Ferrara, whose confidence in my ability to survive University never wavered, as well as Antonio Latella and Luciano Valsangiacomo, who taught me that studying our past is not just a boring exercise exclusively involving dusty books or neglected ruins, but that it is instead a necessary element to understand our present and a defining aspect of our cultural identity.

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Finally, I would like to express my deepest gratitude towards my family and close friends, who never hesitated to push me and kick me, whenever necessary, to better help me put things into perspective throughout the long, difficult, and sometimes sleepless, process that has been the preparation of this work. A special thanks to Margherita and Valentina Foni, my sisters, as well as to Carlo and Tiziana Foni, my parents, who taught me how to appreciate art in all its forms, and who educated me to value, preserve, respect and treasure our cultural heritage: their unconditional patience, reassurances, understanding, love and support have been essential during all these years.

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Chapter 1. Introduction

From the dawn of time, and during the course of centuries, humankind has always shown the need to build organized groups to survive the hostile environment and to optimize their collective efforts through a rational subdivision of the tasks and duties among the members of their collectivities. This behavior originates from the need of these collectivities to effectively gather the necessary resources to sustain their communities and from the desire to grow stronger from their respective differences. At first these groups where small and disperse and lived primarily hunting and collecting fruits and vegetables naturally found in the environment, later the advent of agriculture and the domestication of animals allowed these communities to grow larger and settle to form the first villages.

Later, these collectivities expanded themselves, encountered other neighboring communities and started to exchange their resources extending their network of interrelations. Slowly the necessity to create some kind of superstructure capable to regulate the interrelation between the growing number of individuals and between groups issued from a common region began to rise and different forms of social and political structures started to appear. Eventually some of these communities gave birth to whole civilizations, empires, cities and republics that rose and fell through the course of history, due to natural causes or due to the shock they may have accused clashing between themselves, through cultural assimilation or military conquest.

Another peculiarity that mankind has demonstrated to be inclined to, is its necessity to express its creativity, to record the past events in order to better understand the present challenges and to adapt themselves to their environment, or to modify it in order to make it more suitable for their needs. For these reasons, during their lasting, these civilizations evolved, gave birth to exceptional individuals, developed philosophical, legal and religious systems, made fascinating discoveries and invented amazing techniques, built remarkable structures and produced fine works of art. Rarely these civilizations disappeared without leaving any trace of their presence or passage; nor were destroyed completely when they were subjugated by other civilizations. More often, their infrastructure would rather have been integrated, preserved or used to similar or other purposes by the new order in place and, in some cases, the population would have been assimilated in the new social structure through an intercultural bi-directional socialization mechanism. In other terms, on the long run, the adopted and the adopting civilizations could respectively influence each other to the point at which they would share or acquire some of the values, social behaviors or beliefs of the other one. This process would create a more stable society that could benefit from the differences between the two amalgamated cultures and that could reduce possible raising cultural and social tensions.

The world as it is today is often the reflection of the marks that all these successive civilizations have left in the course of their development on the trails of history. It is not possible to understand the problems, cultural differences and challenges that we are facing today without the knowledge of the past and of the roots from which our present has directly developed. Our respective cultures, belief systems, philosophical approaches, political systems, technological and scientific knowledge, language and more generally our forma mentis are, in fact,

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the legacy of the past civilization that preceded us and upon which our societies emerged and developed. Since we, as individuals, are best defined by our cultural background, more than by our social one, we cannot ignore the lessons and the heritage that was entrusted to us by our ancestors. This legacy was preserved throughout the centuries, generation after generation, and we are bound to transmit it to our descendants as a concrete testimony of the development of humankind and its diverse societies, because without the knowledge of the grounds that made possible the growth of our culture, without our culture, we lose what makes us what we are.

In this respect, our cultural heritage, specific to each community, is a precious legacy that encapsulates the origins of the diverse spectrum of possible societies and ideas that humankind has experienced, built or produced, and that even today has a strong influence on our daily life, even at a subconscious level.

Our cultural heritage can encompass very diverse items such as our religion, mythology, philosophy, architecture, poetry and literature, artifacts, dialects and languages, paintings or statues. It is evident however, that while all human production can be generally considered as our cultural heritage, due to practical limitations it cannot equally be protected in its entirety. Therefore, since it is not possible to preserve everything that is issued from the human production, the question of the relative importance of the separate items that constitute our collective heritage could be posed. It is clear that some items could be categorized in respect of the degree of importance that they represent for the communities at their different levels or in respect of their rarity. For example, a cultural item that is perceived as important at the level of a certain village, such as an old farmhouse, could be considered less important, if a choice should be made, compared to a cultural item that is perceived as important for a whole country, such as an old roman vestige. More generally, we can therefore define our cultural heritage as any human production that bears witness to a certain stage in the development of a certain civilization and that should be protected for the general interest and preserved for future generations.

Our heritage does however not limit itself exclusively to concrete or abstract productions of the human mind. If we are to draw a parallel between the evolution humankind, its civilizations, cultures, societies and the slow evolution and development of our environment, we clearly see that not only some natural places are invested with a cultural significance due the connotations that they may have in respect to certain human cultures, activities or beliefs, but that they possess an inherent importance on their own. Through the course of centuries different civilizations periodically clashed and history has been often characterized by the alternation of periods of war and peace. These struggles, along with natural disasters, have constantly threatened, to a certain extent, the preservation of human cultural heritage due to their inherent destructive power.

In the past, natural cataclysms, such as, for example, volcano eruptions, were in this respect more dangerous than the fires of war, and respectively human activities had a limited impact on the natural environment.

The advent of the industrialization and the modern times inverted this relation.

The scientific advances, applied to warfare and to the civil society, made progressively possible to decrease or prevent to a certain extent the damages that could come from natural causes, but on the other hand, they equally

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allowed humankind to create weapons that could match the destruction brought by the most severe natural cataclysm. Moreover, the impact that human activities had on the environment grew more important with the massive urbanization and the atmospheric pollution caused by the growing use of polluting energy sources and chemical compounds employed by the industry. In a relatively short time, humankind managed to reshape and modify, with new tools and techniques, the landscape to better adapt it to its needs. Only recently, we have measured and considered the extent of the negative impacts that such radical changes in our societies had on the development of the natural environment, ranging from climatic changes, which threaten the survival of certain biotopes and generally harm the biodiversity, to the destruction or alteration of unique natural places. Since our diverse natural environment and its uniqueness made possible the appearance of human civilizations and their survival, we should consider it as an essential part of our heritage that we are equally bound to preserve from the dangers our societies may pose, trying to maintain its delicate balance. For these reasons, in respect to the general definition that we used to characterize human cultural heritage, natural heritage could therefore also be defined as any natural phenomenon or manifestation that bears witness to a certain stage in the development of the natural world and that should be protected for the general interest and preserved for future generations.

Our collective heritage, either issued from human cultural production or issued from the eminently creative and astonishing work of nature, should then be protected, conserved and preserved to the best of our abilities against the dangers to which it could be exposed: natural disasters, pollution, destruction caused by armed conflicts, vandalisms, pillage, economic speculation, ignorance. In order to preserve the knowledge of the past and promote the awareness of the delicate balance of our environment, different methodologies have been experimented in the past. This approaches range from making written or pictorial reproductions, to establishing specific documentations and archives, to the democratization of the access to education and the instauration of museums and research institutions, to the creation of divulgative essays and informative campaigns targeting the public.

The recent development of new digital information and communication technologies and their rapid diffusion among all the different strata of our societies, due to a fast process of democratization to their access, has triggered a profound societal change that affected and modified in a substantial way most of the aspects of our daily life. The emergence of these new technologies, accompanied by an increasing interconnectivity of these information systems on a global scale, has redefined and modified our work habits, our social interactions, our educational system and even our entertaining activities with the appearance of new media. The advent of the digital age and the revolution that modern countries have experienced with the introduction of these new technologies, offers new tools, possibilities and chances for the protection of cultural heritage while providing the main actors that are involved in this fields with new supports to document, analyze and disseminate pertinent and reliable material concerning specific cultural items. Moreover, the introduction of modern 3D visualization technologies, popularized through the increasing diffusion of

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video games, the recent advent of low cost, high performance GPU based video cards and CPUs, in conjunction with the recent advances in the field of interactive 3D graphic and scientific visualization, have opened exciting new opportunities of integration and synergy between these technologies and the classical approaches traditionally applied to cultural heritage protection.

The scope of this thesis is to analyze the new possibilities and perspectives that are offered to the actors involved in the field of cultural heritage protection by the introduction of these new information and communication technologies. Even though a general presentation of all possible visualization approaches and methodologies, both traditional and modern, will be introduced, our primary focus will be centered on the technologies that are issued from the field of 3D visualization and simulation when applied to cultural heritage items. Our attention will be mainly directed towards the different actors whose work is in direct relation with cultural heritage, towards the specific needs their work involves and towards the expectations they display in respect to the introduction of 3D visualization technologies. One of our central interests is to clarify which opinion they have regarding these technologies, which usefulness they see in their introduction in their specific field of activity and under which conditions and to which extent they are willing to consider them as a valid new tool. An equally important aspect we will explore is whether these new methodologies can represent a positive addition and a real contribution to the usual approaches these actors normally implement in the frame of their activities, and how these new tools can be integrated with the traditional ones they are used to rely upon.

This chapter will present an introduction to the themes and elements that will be discussed, analyzed and formalized more in depth in the following chapters. An overview of the actors and approaches that belong to the domain of cultural heritage protection will be presented along a brief summary of the general themes and objectives we seek to investigate in the development of this thesis.

1.1 Background: actors involved in cultural heritage

The general definition of cultural heritage, as previously introduced, regroups a wide range of items, ranging from small artifacts and large natural or built sites, to more abstract notions, like specific languages and oral tradition. Likewise, the range of activities, studies, institutions and research fields that are linked, directly or indirectly, at different levels, to the protection, promotion, conservation, interpretation and investigation of this heritage is very broad and regroups diverse actors.

Concerning the protection and conservation of cultural heritage, we can mention the role of international organizations, whose mission is to identify world heritage items, to promote and define guidelines and standards for the practical protection and the safeguard of cultural heritage and to instigate the conclusion of treaties, intended for the member states of the international community, to institutionalize the necessity for the protection of cultural heritage at a global scale. Then we can cite the essential involvement of national governments and regional and local authorities, which is indispensable to implement effective policies aimed at the safeguard of our heritage as well as to guarantee the availability of concrete means to achieve this goal of public interest. At last, we

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should equally consider the public structures and agencies that could be directly involved with the safeguard of cultural heritage, such as the ones specialized in the cataloguing of heritage sites and items, or the ones that are to intervene when a real danger is menacing those items. Depending on the nature of the threat, we can cite organizations such as, for example, the police, the fire departments or the civil protection, or even private bodies like artisans, architects and restoration specialists.

Regarding the interpretation and investigation of cultural heritage, two broad categories, and their different specializations and related fields, are primarily concerned: historians and archeologists. Each of these groups strives to better apprehend the past, to better understand past civilizations, historical periods, their changes and revolutions, either political, social, ideological or technical, and more generally to comprehend the mechanisms, forces, interrelations and mistakes that characterized the development of humankind. Access and analysis of original sources and documentation, written, pictographic or physical, and availability of consistent data is a prerequisite for their work to be carried out in suitable conditions, and their mission relies heavily on the capacity of the previously mentioned groups to provide an adequate protection of our collective heritage. Since these two groups are the wardens of the knowledge we have of our past, and of our capacity to interpret and learn from the lessons we may find in the path that humankind has taken through its evolution, they are equally the most competent to identify and recognize whether a specific item is characterized by any important cultural significance and whether it belongs to our cultural heritage. Thus, the work of such specialists plays a fundamental and essential role in the determination and identification of those items, and their collaboration, supervision, expertise, dialogue and interaction with the other actors involved in the field of cultural heritage ensures the definition of valid, effective and coherent lines of action.

In relation to the promotion of cultural heritage we can point out the mission of divulgation, knowledge dissemination and education carried out by entities such as museums, the educational system at all its levels and the public authorities through actions such as awareness campaigns organized either by the press, the media, the action of individuals or by institutions with the publishing of books, essays and papers related to the topic of cultural heritage. More generally, these are the actors that produce, diffuse and divulgate information pertinent to the field of heritage protection. In this respect, first the educational institutions, then the media, due to their coverage and the possibility to reach a large spectrum of the population, are in the best position to raise the awareness of the public towards our cultural heritage. For these reasons, those groups are the ones that could benefit the most from the new synergies between the new information technologies and the traditional methodologies associated with the presentation and divulgation of material related to cultural heritage. Concerning this last point, it has to be stressed that the public, generally supposed to receive the results of the actions and initiatives initiated by the previously mentioned groups, is not a passive element but should be regarded as a full actor, whose needs and expectations should be considered to ensure that the messages convoyed by those initiatives are properly targeted, suitably transmitted and correctly perceived by it.

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Finally, if we consider the possible interactions and collaborations between the new digital information and communication technologies and the previously cited groups of interest, we should note the central position that technicians and information and visualization specialists occupy in the frame of such interrelations and synergies. Since these technologies generally require a certain amount of technical expertise to be deployed efficiently, it is clear that the main group responsible for the development of adapted tools to be integrated in the traditional pipelines is represented by the experts and researchers connected with these new fields. One specific area towards which we will particularly direct our attention is the field of computer aided visualization techniques applied to activities and applications relevant to cultural heritage protection, documentation and dissemination.

In view of the fact that the groups involved in the area of research and development of new digital tools generally present prototyping cycles of variable length, in order to deliver usable and stable applications, the existence of strong ties, communication channels and feedback mechanisms between those and the previously identified actors must be guaranteed. The most exciting visual application or the most astonishing digital tool intended for cultural heritage, despite being developed with the best possible intentions or employing the most advanced technologies, loses all its meaningfulness and usefulness if the needs of the targeted groups are not properly considered during its development stages. A multidirectional and reciprocal communication between the information specialists and all the concerned actors is therefore indispensable for these new instruments to actually represent a valid option to be integrated alongside the existing traditional methodological tools available to those groups. Likewise, the existence of such consultation mechanisms, and the implication of all the targeted actors and intended users in the conception and development of these new tools, would facilitate a positive reaction, an optimized impact and a better response to the diffusion and adoption of such tools by those groups, triggered by their increased effectiveness and usefulness.

1.2 Traditional Approaches

All the groups that are involved into cultural heritage related fields have developed specific tools and methodological pipelines that are suited to apprehend the particular dimensions of a cultural item toward which their mission and work is directed. Some of them may be more interested in the extent of the historical substance impregnating the item, others in the successive possible uses to which it was destined through the centuries: their objectives could therefore be different, ranging from analyzing the object to extract useful information to better understand the past, to preserve it for future generations against possible threats that could compromise it. Although their finalities might be different, the tools employed by those groups to apprehend the dimensions of the concerned item are often similar, even though their use might differ from case to case. The traditional approaches, with which the concerned actors are commonly used to work, and that were adapted to their specific needs, are generally characterized by the presence of strong components of manual, physical or mechanical work, and by the presence of paper based, not reusable, supports.

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An additional particularity of such tools is their relative accessibility and their limited flexibility: given the necessary prior intellectual knowledge, the amount of time required to deploy them on the field is generally short and does not necessitate any particular preparation. On the other hand, these tools can subsequently generate a considerable amount of work in the further manipulations and modifications that the collected data could demand.

Moreover, these tools profoundly rely on the creation of a direct relation between the observed item and the observer, hence disallowing the possibility to post process or improve the quality of the gathered data without further direct contact with the concerned item.

As some examples of such tools in the sphere of cultural heritage analysis, study, documentation and conservation we can cite: the direct on site observation, intervention and manipulation of the concerned items, the constitution of extensive written descriptions, the depiction of sketches and the preparation of restitution drawings, the establishment of architectural, archeological or topographical plans and sections, the creation of visual recordings and the organization of photographical surveys. In order to illustrate to a better extent the abovementioned characterization, we can take as examples directly connected to the field of visualization the case of photography as a tool for documentation, and the use of architectural plans as a tool for intervention and protection.

In the specific case of the photographic documentation of a cultural heritage item, given the basic prior knowledge of the manipulation of a camera, no particular preparation is necessary to start the gathering of data: it is sufficient to setup correctly its controls, considering the lighting conditions, arrange, if necessary, some form of artificial illumination, and take the picture. Subsequent to the data gathering process on site, the film is developed and the pictures are printed: such procedure requires a certain amount of time and expertise in order to produce optimal usable results. However, the results of this process could present specific problems, such as, for instance, overexposure, underexposure or the presence of excessive blur, which would require the shooting of new images of the concerned subjects. In some cases this necessity could lead to organizational or logistical complications, since a further session should be arranged on site and the concerned items inspected for a second time. Once the final material meets the fixed requirements, the negatives are used to produce the necessary number of copies for further use. One advantage that printed pictographic documentation presents is that is generally easily accessible by non-specialists and efficiently conveys its information; its disadvantage is that, due to its fragility, it has to be properly conserved, since its support tends to degrade easily. Moreover, in order to produce copies of such material the exploitation of the physical negatives is necessary: their proper conservation is therefore essential to ensure the reusability of the originally collected data.

In the case of handmade architectural descriptive plans or drawings, similar remarks can be made. While it is relatively easy to deploy such measures, given the proper talent and the understanding of the necessary notations, it is more delicate to preserve the finalized work, to further modify or rectify it, and to quickly prepare and disseminate the necessary copies to the actors that require them to fulfill their mission. Furthermore, in the specific case of architectural

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plans and sections, it is important to note that, due to their inherent technical nature, they could pose some clarity problems in respect to their interpretation and exploitation by non-specialists. This kind of representation, in fact, usually does not convey its information intuitively, and since it could be used as a base, or reference, to prepare evacuation and intervention plans, intended for field personnel responsible for the protection of heritage items in the occurrence of natural catastrophes that would require expedite action, such as floods or fires, the exploration of alternative methods to ensure a better transmission of such information could be constructive.

Beside the evident benefits that such tools and methodologies offer, it is clear that they do present some inherent limitations and practical restrictions in their implementation which could be optimized. In this respect, the introduction of new approaches issued from the recent advances made in the development of digital media, communication and visualization technologies could reduce the extent, impact and repercussions of such constraints, while allowing a lessening of the amount of manual and repetitive work that is required to ensure a better reusability and ease of manipulation of the produced results.

1.3 Advent of New Media and Digital Tools

The second half of the twentieth century witnessed the rapid development of information related technologies and their fast, generalized diffusion in the occidental civil societies at all levels. The appealing possibilities offered by such technologies, first in terms of data management and numerical computing, later in terms of optimization and automatization of repetitive or time consuming tasks, triggered their progressive migration from the sphere of military applications, to the field of scientific research, to their adoption in the area of commercial applications in order to allow for a better productivity and efficiency.

The progresses made in electronic miniaturization, energy consumption and interface ergonomics, and the consequent reductions of manufacturing costs, subsequently facilitated the access to such technologies and assisted their diffusion. The introduction of the first low-cost personal computers produced an acceleration of this phenomenon, marking their transformation into ordinary and necessary tools present in all the aspects of our everyday life, and equally signed the emergence of a first digital revolution.

A distinctive trait that characterizes such technologies is the inherent diffusion of digital supports supplanting the traditional ones, and the progressive adoption of the no-paper paradigm. Slowly, the conventional physical paper based format formerly favored to support our written production changed to assume an immaterial digital form. This change offered undeniable benefits, such as for instance the possibility to freely modify a given text without the restrictions characterizing the physical supports. On the other hand, the problem of the preservation of such digital supports and their content, to ensure a long-term persistence of our production, has to be considered. Currently available portable and fixed digital supports present remarkable storage capacities, allowing the condensation of large amount of data, that otherwise could have filled entire libraries, in a relatively small space; however, these supports suffer a certain structural fragility that can compromise their content: such occurrence could

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have catastrophic effects due to the high concentration of information they can hold. To prevent such eventuality, the creation of redundant data and the instauration of data replication and duplication mechanisms are necessary.

Likewise, the growing acceleration in the development in this field, both hardware and software oriented, caused the emergence of a rapid obsolescence phenomenon striking digital supports and data formats. In this respect, although a digital support can be properly preserved form physical degradation, it is still necessary to preserve as well the means to access and read its contents. At short term, this could be achieved by ensuring the retro-compatibility of older formats in new software, or by transferring the content to other media when the obsolescence concerns the physical support itself and the devices able to read it. At longer term, other solutions must be considered, like for instance hardware emulation or even the complete physical preservation of the original hardware and software used to produce such contents. In view of this concerns, it is interesting to note that although the advent of the digital era has offered like never before the possibility to easily create, manipulate and archive all sort of information and intellectual production, paradoxically has never been so difficult to preserve at long term such digital production from degradation caused by the passing of time.

The rapid increase in the computing performances of central processing units and the augmentation of the storage capabilities of digital supports, progressively allowed for the handling of even more complex data. Such evolution marked an extension of the applicative possibilities of informatics, facilitating the introduction of digital tools in a varied array of fields. Thus, due to the increased capacities featured by computerized systems, the digital manipulation of material constituted not only by textual information became achievable. The opportunity to digitally create, archive and modify music, images, videos, and more generally multimedia items, became accessible, encouraged by the diffusion of low-cost dedicated hardware intended to accelerate such particular tasks, and specifically adapted to handle such data, such as, for example, graphical and sound processing units respectively specialized in the treatment of video and audio operations. The diffusion of these new tools, joined with the increasing development of their computational power, equally introduced the possibility to manipulate such large amount of data more interactively while providing an increasing number of operations with the support of real time feedback to the user. These capabilities are particularly interesting when applied to the fields of computer graphics, scientific visualization and more generally to the fields that are aiming at the reproduction and transposition of specific attributes of the physical world and its characteristics into computerized models and synthetic representations for testing and simulation purposes. Such potential coupled with the emergence of three-dimensional visualization technologies and with the advances made in image synthesis and rendering, provided the means to reach a digital representation of reality closer to its original counterpart. Moreover, the synergy between these new tools and the multimedia properties of the newly available supports and digitally exploitable data, has allowed the surfacing of new approaches and opportunities applicable to content creation, manipulation and interaction. At the same time, the possibility to link, layer and encapsulate different types of information to such

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content encouraged the development of new forms of knowledge transmission and interpretation, and eventually gave birth to new means of semantic communication and expression.

The evolution of digital information technologies and the diffusion of digital supports were accompanied by the progressive development of communication related technologies and their infrastructure. The last decades of the twentieth century have witnessed the outcome of a second digital revolution represented by the extension of the interconnection capabilities between computerized systems at a global scale alongside the development of mobile applications. The rapid development of the Internet, its adoption as preferred support to provide fast access and dissemination of information and services and the low cost availability of broadband channels facilitated the introduction and diffusion of such technologies in the civil society and to the general public; this developments fundamentally modified our social habits concerning the way we relate ourselves to the intercommunication process. The improvements in both spatial extension and transmission speed of networked environments have provided new communication and data manipulation tools that have modified our working environment. The diffusion of instant messaging software, e-mails, shared data repositories remotely accessible and the possibility to establish collaborative environments have extended our capability to quickly and easily reach different people and retrieve pertinent information on a global scale, independently from their physical location.

Moreover, the increased interconnectivity of digital networked systems, have equally allowed the sharing and exchanging of decentralized heterogeneous resources between multiple users to be employed for dissimilar purposes.

Finally, the convergence between the multimedia capabilities of computerized systems and telecommunication and network related technologies, have both provided new methods to convey, disseminate and access digitally stored reusable resources, and have created new opportunities to reach and interact with larger audiences, hence ultimately contributing to the establishment a of a new medium for content manipulation and transmission.

1.4 Modern Approaches to Cultural Heritage Protection

Given the growing possibilities that are offered by the new technologies of information and communication, and the development of new multimedia applications for the digital representation of information, the fields related to cultural heritage preservation, protection and interpretation can clearly benefit from the adaptation and adoption of such new digital tools. Their introduction could then contribute to the establishment of new approaches and methodological pipelines that are particularly adapted to the cultural heritage field. Such new approaches, which are based on the extensive use of digital tools, are generally characterized by the presence of strong components of automatization in the acquisition, treatment and processing of the data relative to the investigated item and by the presence of reusable digital supports to store the gathered information.

Additionally, these tools feature a relatively limited accessibility and an extended flexibility: the deployment of such tools on the field requires a good

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understanding of their technical functioning, and necessitates the setup of specific conditions to ensure the acquisition and creation of exploitable information. On the other hand, given the appropriate technical competencies, the amount of work necessary to further manipulate or modify such material in its digital form is greatly reduced. Moreover, these tools do not require the creation of a permanent direct relation between the observed item and the observer, therefore allowing the possibility to interactively rectify, modify, enhance, adapt and manipulate the gathered information without further contact with the concerned physical item. Finally, these tools give the opportunity to organize and present heterogeneously gathered data on a unified medium, while allowing a user to simultaneously consult, interact and access a varied combination of different content resources, such as, for instance, textual, pictographic or musical information.

As a few examples of the possible application of such digital tools to the sphere of cultural heritage, we can cite: the creation of digital catalogues and databases for the consultation and retrieval of the digitally archived material, the digitization of paper based sources through optical scanning for analysis, conservation studies or long term preservation, the digitization of physical artifacts through laser scanning techniques, the constitution of bi-dimensional or three- dimensional CAD models for simulation, hypothesis testing, restitution studies or dissemination purposes, the creation of digital visual recordings and the organization of digital photographical surveys. To better understand the specificities and possibilities offered by the application of digital tools, we can consider, similarly to the development we employed concerning the illustration of the traditional methods, the specific cases represented by digital photography and computer aided architectural drawings.

In the specific case of a photographic documentation, the advantages offered by the introduction of digital technologies are manifest. After the on site gathering of the digital pictures, the acquired material is directly exploitable and accessible by different computer applications for varied purposes. It can be stored and linked to a database together with other pertinent information relative to its subject for archiving, or it can be easily manipulated and modified for further use. Even though a correct setup of the shooting conditions should not be disregarded, the possibility to digitally correct and rectify the collected images, through operations such as, for instance, perspective correction, color balancing, exposure compensation or tone mapping, offers a considerable asset. The opportunity to post process such data thus lessens the necessity to reacquire most of the compromised material and therefore limits the need to organize further sessions on site.

Moreover, since digital cameras generally feature the capacity to store a much greater amount of images than traditional ones, and offer the possibility to visualize such data immediately after the acquisition, the necessity to carefully control the shooting conditions is significantly reduced. By employing a traditional camera such precautions are clearly required, since the results of the shooting can only be observed after the printing process of the negatives. On the contrary, the use of a digital camera allows for the instant verification of the results: in the eventuality that a specific picture presents excessive flaws, such image can easily be deleted and replaced by a new one. Furthermore, since the

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acquired images are stored on a digital support, such data can be straightforwardly distributed and accessed by multiple users: digital copies of the original image files can be made effortlessly if specific users need to modify them for their particular needs. Additionally, several printed copies on physical paper based supports can be produced as well, either of the original data or of its modified versions, without having to go through time-consuming processes.

In the case of the preparation of computer aided architectural descriptive plans or drawings, similar remarks can be made. The introduction of computer aided tools provides the possibility to effectively archive, retrieve and modify digitally produced drawn material, and it offers the necessary assistance to expedite the interactive data creation and refinement processes. Lines and surfaces that might be incorrectly placed can be quickly erased and corrected without altering the working support, as it is the case when employing a pen and paper approach to execute the same activity. Moreover, the inherent information present in the digitally produced plans can be extended by the superposition and inclusion of additional data, such as for instance material attributes. In addition, such plans can be transposed, with appropriate tools and with the necessary expertise, into three-dimensional models of the concerned items. Such models primarily present the advantage to offer the possibility to rapidly produce arbitrary sections of the studied object and to quickly create perspective views of its volume and appearance by using real world parameters to simulate a virtual camera. Inversely, the preparation of additional sections and isometric representations manually created with the help of traditional tools would necessitate a considerable amount of time and effort.

Additionally, the digitally portrayed item can be interactively visualized under different angles and could be employed to create high quality nearly photo realistic renderings of specific static or animated points of view, producing as results either an interactive application, a set of images or an animated movie.

Secondly, three-dimensional rendered visualizations feature a more pronounced accessibility and a better clarity concerning their interpretation and utilization by non-specialists than bi-dimensional plans and section on a paper based support.

The exploitation of the newly available multimedia capabilities of modern computers, coupled with the digital visualization possibilities offered by computer graphics, therefore provide, in this respect, more adapted ways to efficiently and intuitively convey pertinent and accessible information regarding the concerned items. Such advantages can be particularly significant when expedite decisions or actions are required from field personnel, which has to access such information to coordinate their activity in order to protect cultural heritage related items from the sudden occurrence of some sort of threat to their integrity.

Most of the previously cited methods are clearly intended to produce a computerized representation of real items and their characteristics, especially those that include a visualization component. Some of them are simply a direct transposition of traditional methods with the addition of digital features, as it is the case with architectural drawing: the nature of the task is the same as the one performed with traditional tools, but it is achieved through the use of specialized software while replacing the traditional supports with a computerized interface.

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In this respect, it interesting to note that such examples can be classified depending on the varying degree of relation they feature toward the studied item. Certain tools, such as optical scanning, produce as a direct result a digital counterpart of a real object through a digitization process: the original resource still exists and is the essential base for the creation of the digital representation.

Other tools, inversely, produce results that are fully digitally created: no intermediary step and little to none physical relation is necessary between the real object and its digital counterpart. This difference clearly appears if we consider the example of photography. One approach consists in employing a normal camera, developing the pictures shot and later scanning the printed supports to transpose them into a digital format; another approach consists in using a digital camera in order to have the pictures directly available in a digital format without requiring the digitization process. This distinction clarifies the double mission that the introduction of digital technologies has to fulfill. First, it has to support the documentation, study, dissemination, protection and conservation of cultural heritage with the creation of new tools and by providing traditional ones with increased capabilities. Secondly, it needs to assist the transition that has to be applied to the already constituted resources, stored or produced on traditional supports, to transpose them to new digital formats and supports.

As a concluding remark, it is important to note the central role that information specialists have in the implementation and deployment of such new technologies. As they are in the best position to understand the real possibilities and the inherent limits that such new tools present, their responsibility as intermediaries between the needs expressed by the end users and the development of specific applications that could answer those necessities is indispensable. In order to guarantee an adequacy between those requirements and the proposed solutions, the prior knowledge and understanding of such constrains is crucial: any developed application could otherwise entirely lose its usefulness. Moreover, due to their increased exposure to technological novelties information specialists and researchers find themselves in a privileged position to consider the possible applications that such advances could offer whether transposed to other fields, such as cultural heritage.

Since the impulsion to adapt, extend and implement new digital tools issued from the scientific research could as well come from the sphere of informatics as a mean to verify, test or validate newly developed approaches or technologies, the risk to create specific ad hoc tools exploitable only in the context of a given case study exists: in such case, these tools would then be characterized by a limited usefulness and by limited generalization possibilities to other cases.

Therefore, in order to establish a coordinated effort and a coherent approach to the application of such new technologies to these fields, the role of supervision and consultation provided by the specific experts, such as, for instance, historians or archeologists, is essential to ensure a proper degree of usability of the created content as well as a suitable degree of adaptation of any developed application to the end user requirements.

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1.5 Problem statement

The use of graphical representations, usually in the form of two dimensional drawings or handmade perspectives, along with carefully noted measurements of the considered elements, constitutes one of the first attempts to better preserve, extend and divulgate the documentation relative to archeological, historical and, more generally, cultural heritage items [OGLEBY01]. Moreover, the creation of detailed handmade restitutions represents a precious support that allows for a better understanding of the context in which those items were built or manufactured. These representations equally offer the possibility to graphically experiment, easily convey and formulate possible hypothesis [SANDERS99] regarding the original supposed appearance of a heritage item at the time it came to existence, thus satisfying the need to provide an accessible way to document the item and offering, at the same time, a support for the interpretation of the findings. The democratization and advances in information and visualization related technologies have opened new ways and forms to present, analyze, preserve and divulgate the documentation relative to cultural heritage items, as well as they have both offered new supports to produce restitution studies for the purpose of hypothesis testing, and have provided the possibility to reach a broader audience [MILLER94] [FORTE97]. Nevertheless the perspectives offered by the particular use of 3D digital representations in the field of archeological and heritage preservation [REILLY92], raises some methodological issues as well as some questions regarding the optimal form, the type of media, the correct approach and the specific technologies that can be deployed in order to achieve a result that satisfies both the preservationist’s need for documentation, the historian’s need for interpretation and the public’s expectations for a high visual realism [ADDISON00].

Even though several projects that rely on different technologies and approaches, aiming at the creation of virtual representations of heritage sites, have been developed in the past years, no clear methodology has been identified in order to achieve an optimal balance between the expectations and the needs of the all the groups that could have been targeted by those reconstructions, thus limiting the benefit of such work only to one specific group of end users. For instance, the reconstructions that are targeting the general public through computer generated movies rarely encounter the appraisal of archeologists, while, on the other hand, restitutions that target primarily archeologists and historians appear often less accessible for the general public [SIDERIS02].

1.6 Motivation and pertinence

Given the fact that the domain of cultural heritage can intersect with the respective fields of diverse groups and actors, meeting their interest for dissimilar purposes, it is evident that some kind of common ground is needed to allow a proper communication and a mutual understanding between all the parts involved in order to ensure the establishment of consistent approaches and constructive collaborations. Since the nature of cultural heritage is profoundly interdisciplinary, the definition of a set of adapted and effective methodologies is therefore primarily relevant for projects targeting such domain. The constitution of such methodologies is even more pertinent and valuable when the actors that

Methodological approaches for the protection of cultural heritage in the digital age

Thesis

Reference