C er-A Cyb Arch haeologyy E Edited by b M rizio Fortee Maur B BAR Innternaationall Seriees 21777 2010 Published by Archaeopress Publishers of British Archaeological Reports Gordon House 276 Banbury Road Oxford OX2 7ED England bar@archaeopress.com www.archaeopress.com BAR S2177 Cyber-Archaeology © Archaeopress and the individual authors 2010 ISBN 978 1 4073 0721 3 Printed in England by 4edge, Hockley All BAR titles are available from: Hadrian Books Ltd 122 Banbury Road Oxford OX2 7BP England www.hadrianbooks.co.uk The current BAR catalogue with details of all titles in print, prices and means of payment is available free from Hadrian Books or may be downloaded from www.archaeopress.com 3D Cybermaps of Western Han Mural Tombs Fabrizio Galeazzi, Paola Di Giuseppantonio Di Franco and Nicolo Dell’Unto University of California, Merced, USA. Abstract The Virtual Museum of the Western Han Dynasty Project is a joint research between UC Merced and the Jiaotong University aimed to the digital documentation of archaeological sites, artifacts and cultural relics of the Western Han Dynasty. The outcome of this process will be the creation of a virtual museum, based on collaborative environments, dedicated to the Western Han Dynasty and able to integrate new archaeological datasets coming from the fieldwork activities (most part of them unpublished), monuments, and famous collections of artifacts of the Xi’an archaeological museums. One of the most important archaeological examples in Xi’an is represented by the mural paintings of the monumental tombs of the Western Han Dynasty. Despite their cultural and historical importance they are at risk of being lost because of the critical conditions of plasters and colors. The murals show a very rich repertory of subjects such as scenes of daily life, rituals and ascension to heaven. These examples of mural paintings contain a very complex interpretation code explaining the relations between life and death during the Western Han dynasty. A simple description of the subjects and also the 3D virtual reconstruction of the tombs are insufficient for approaching a correct cultural interpretation. In this paper we present a preliminary case study on the semantics of the tomb M 27’s iconography (excavated in Xi’an in 2004 and documented by laser scanning) obtained through 3D virtual cybermaps. The use of virtual-cyber mind maps emphasizes the interpretation of the spatial, religious and symbolic connections (affordances) of the different subjects and images decorating the vault and the walls of the tomb. Through this simulation process the potential semantic recomposition of the tomb creates new metaphors of learning and communication. Key words: 3D data collection, 3D reconstruction, cybermap, communication, learning process. monuments are mainly discovered during emergency surveys in construction sites. In the last few years the city has rapidly increased, and archaeologists are forced to collect quickly all the information on the ancient sites before them to be covered again, and disappear under a modern building. M 27 is one of the fortunate tombs to be physically preserved. But, unfortuately, the lack of economical resources prevent both a good preservation approach, and the public fruition of the monument. For all these reasons the VHLab’s work is of extreme importance, because it permits the preservation of the monument through the digital documentation. This is not the only important aspect of the data-collection fieldwork. The data have already been processed in the lab, and the outcome has been the 3D virtual reconstruction of the tomb. If the model is useful for preservation aims, it is not enough when talking of musealization. Without a good infrastructure for showing the original context of any monuments, every 3D reconstruction becomes an empty box. The virtual musealization doesn’t differ from the real. Every archaeological site, every museum, need infrastructures useful for the comprehension of ancient contents. 1. Introduction The Xi’an University of Technology Mural Tomb (M27) is an important monument discovered in the city of Xi’an and excavated in 2004. In June 2008 members of the University of California Merced and the Italian CNR (Bational Research Council) VHLabs (Virtual Heritage Lab) went to Xi’an and could survey the monument using a laser scanner. The mission, directed by Maurizio Forte, was possible thanks to an agreement between UC Merced and the Jiaotong University of Xi’an, aimed to the digital documentation of Western Han monuments for preservation and communication pourposes. The outcome of the project will be the creation of the Western Han Dynasty (206 BC-9 AD) Virtual Museum based on collaborative environments, and able to integrate new archaeological datasets coming from the fieldwork activities, monuments, and famous collections of artifacts of the Xi’an archaeological museums. M 27 is one of the few Western Han Mural Tombs discovered in the city, which was the capital of the Western or Former Dynasty under the name of Chang’an. Despite its importance, the preservation of this heritage is at risk. In particular paintings inside the tomb are disappearing because of the critical conditions of plasters and colours. Since they are made over a very thin stratus of clay, directly applied on the bricks composing the structure, their removal from the walls and preservation inside a museum is impossible. A common problem, when thinking to heritage communication, is the traslation of all the information in a comprehensible and explanatory musealization system, that could help visitors to interpret ancient codes. For the M27 case-study we tried to create this infrastructures working on the idea of 3D cybermaps. With the term cybermap we define the 3D graphic translation of those spatial connections. This is not the only case. Every year, in fact, chinese archaeologists in Xi’an discover hundreds of tombs. The 97 Cyber-Archaeology 2. Xi’an University of Technology Western Han Mural Tomb Xi’an University of Technology Mural Tomb is located on Leyou Plane, northwest of Yue Jiazhai Village in the south suburb of Xi’an (fig. 1,). Originally it had to be surmounted by an earth mound on the top, that was cut during the 1950s and 60s. The mural tomb was excavated between January and March 2004.1 During the excavation robbery holes were found in the north wall of the tomb chamber, and on the brick wall closing the main chamber entrance. The monument is characterized by the following elements: a tunnel excavated directly in the ground; two side rooms, where grave goods were preserved; the main chamber. The orientation is south-north as Chinese houses were traditionally set up in that time. Through the tunnel is possible to have access to the three underground chambers, that are all made of bricks. Figure 1. The Xi’an University of Technology Mural Tomb (M27). We started from the analysis of the paintings, that show a very rich repertory of subjects, such as scenes of daily life, rituals and ascension to heaven, containing a very complex interpretation code, which explains the relations between life and death during the Western Han Dynasty. We think that this contents can be very well understood stressing the spatial relations between every scene. Visiting the tomb we immediately perceived that the orientation and the location of every single scene was of extreme importance. We are convinced, in fact, that in this monument there is a corrispondence between spatial and conceptual relations. The side rooms are located at the end of the tunnel, before the main chamber gate. In the eastern side room four seals and one pottery basin were discovered. In the western room two lacquer wooden chariots were placed in the front and back position. Both were rectangular in plane and had double shafts and single horse. Of these chariots only the lacquer pieces and the bronze ornaments remain, while the wooden part has deteriorated into wooden powder. The main chamber has a rectangular shape (4.6 meters long from the south to north and 2.08 meters wide from the east to west). The chamber wall is 1.25 meters high, and the chamber itself is 2.10 meters high. It was completely covered of frescos. Inside the main chamber, the coffin of the deceased was found located in the northeast corner (2,10 meters long and 0,60 meters wide). Next to the coffin there were two jade eye masks, a jade object outlining in the mouth of the deceased, two jade nose elements, and a jade necklace ornament. Moreover 200 Wuzhu coins and a bronze seal were found in the chamber. The cybermap has been presented in a short movie in which we explored the idea of a learning process obtained through different layers of perception: the virtual recostruction of the tomb, the same model texturized with archaeological sketches, the cybermap. We are also working on meta-data; the final goal should be the creation of an interactive cybermap. In conclusion our work has stemmed from two queries: can 3D data-collection increase the preservation capacities of our cultural heritage? The tomb was dated at the end of the Western Han Dynasty (206 BC-9AD) thanks to a typological comparison with similar structures that were dated, and to the bronze Wuzhu coins discovered inside the tomb. The identity and status of the tomb owner have been assumed based on the size of the tomb, the importance of the burial objects, and the paintings. He was probably a governmental official during the Western Han Dynasty. Can we use these data and different digital tools to improve the communication and the learning process in the museum, and how? To answer to these questions we developed a project divided into several specific tasks: - tomb 3D relief, realized using laser scanner tecniques; - high resolution 3D model of the monument, useful for both preserervation and communication purposes; - cybermap;- short movie to present in public, as the actual output of this project. F.G., P.D.G., N.D. After the establishment of PRC (People’s Republic of China), with the economical development of China, 1 All the information on this tomb comes from the excavation report of the tomb: VV.AA. “Excavation Report on West Han Mural Tomb on the Campus of Xi’an University of Technology”, Cultural Heritage [J], (Issue 5). Xi’an Municipal Institute of Cultural Relics Conservation & Archaeology, 2006. The book was translated in an English inedited version by Lizhi Zhang, Jaotong University of Xi’an. 98 3D Cybermaps of Western Han Mural Tombs building works have increased and archaeologists have found a big number of Han Dynasty Mural Tombs. Over sixty of them have been reported through media, but mostly they are dated back from the period of Xin Wang Mang (9 AD - 25 AD) to the end of Eastern Han Dynasty (25AD - 220 AD). Few Western Han Dynasty Tombs have been excavated so far and, according to incomplete statistics, one is dated at the beginning of the dynasty and eight at the end. Only four are discovered in the region of Chang’an, ancient capital of Han Dynasty, partially corresponding to the modern Xi’an. Their typology and size are similar, but they differ for style, layout and contents of mural paintings. The paintings in the Xi’an University of Technology Mural Tomb are very innovative. They are richer from an ichonographic point of view, and more structured and elegant. The innovation consists in the introduction of scenes of daily life, which become very popular during the Eastern Han Dynasty. In this latter period, in fact, there is a shift from the absolute depiction of celestial figures to the expression of ordinary people, considered the switch from visionary romanticism to rational realism.2 According to Chinese scholars, this tomb together with the XJTU Mural Tomb, has bridged the gap concerning the Western Han Mural Tombs in the central plain of Shaanxi Province, gaining significant academic values in offering valuable references for the study on Western Han mural paintings. P.D.G., F.G., N.D. Figure 2. Side walls of the chamber gate (south): the tomb guardians. Archaeological drawing. 3. Mural paintings description The mural paintings inside the main chamber of the Xi’an University of Technology Western Han Mural Tomb, are realized on a thin white clay layer applied on the walls and ceiling. Because of the nature of the murals, there are important conservation issues that need to be addressed. Even though the mural tomb is closed to the public, and the temperature and humidity are being controlled, timely anti-molding and anti-germ processing have completed, the successful conservation of these paintings is still at risk. They cannot even be detached from the bricks and collocated into a museum, because of the way they have been realized. All the paintings are characterized by a black ink contour line, filled up with natural colors. The main colors are green, white, yellow, red and black, and they have a symbolic meaning linked to the universal elements of chinese philosophy. A second representation of a dragon and a tiger is on the ceiling, respectively in the south-east and in the northwest angle. The green dragon is connected with the sun in front of it -inside which there is a golden crow- and symbolically associated, in the chinese philosophy, to the East and the day. In the opposite angle the white tiger stands linked to the moon -in which there are a toad and a jade rabbit- representing the West and the night. In association with these two fairies, in the middle of the south part of the ceiling, is the red bird of the South (zhuque), which seems to fly in the south direction. The zhuque, or red bird, is sometimes mistaken for the fenghuang, but they should be two separate entities. Fenghuang is a fantastic animal made up of the beak of a rooster, the face of a swallow, the forehead of a fowl, the neck of a snake, the breast of a goose, the back of a tortoise, the hindquorters of a stag and the tale of a fish.3 It represents both male and famale entities as other symols in Chinese culture. Entering in the main chamber, the first subjects that appears in the eastern and western sides of the gate are the two tomb fairies guardians, the dragon and the tiger (fig. 2). They are both in the standing position between clouds, holding a long narrow flag; the dragon body traces an “S” and it is characterized by a sharp mouth, round eyes, double horns, and golden scales; the tiger is winged with black stripes on the back, and the face is not recognizable. 2 南方朱雀, Nán Fāng Zhū Què literally means ‘the South red bird’. It appeared in association with the other three animals during China’s Warring States period (476 BC 3 He Xilin 2001. 99 Chang 1983: 56. Cyber-Archaeology - 221 BC), and they were frequently painted on the walls of early chinese tombs.4 In M27 the bird predominant colour is red, but it is not the only one; the body in fact is yellow, the peacock tail is multicoloured, the long neck is blue. The last cosmic symbol is represented by a snake or a tortoise. They are strangely not depicted on the ceiling, but we can recognize two snakes on the northern wall, where there is the symbolic representation of ascension to heaven for immortal life. On the ceiling it is also possible to recognize three celestial cranes among clouds. All the celestial birds and auspicious animals are flying to the south. In conclusion it can be said that the ceiling reveals the heaven in which the soul of the tomb owner lives. On the northern wall is a Yuren -the celestial being who leads the dead to ascend to heaven for immortal life (plate 3b). He faces a dragon and the west, and his arms are stretching forward in the steady position, as if to hold the dragon snout. He has red face, huge animal ears, round eyes, high nose, protruded lip, curly and fluttering hair, and wings on the shoulder. The dragon is red in belly and green in the back, the head of which has been severely mutilated due to the robbery hole. Below the dragon are a yellow and a green snakes. In addition, there is another animal, which has striking eyes but unidentifiable trunk. Among those images clouds are painted. F.G., P.D.G., N.D. 4. Tomb historical context On the side walls murals are featured by scenes of daily life, which underline the social status of the deceased: In the iconography of the tomb M 27 we can recognize the symbolic expressions of the Western Han culture. - On the eastern wall scenes of horse hunting are represented. On the top of the south end of the wall there are chariot outgoing scenes: the master seems to be represented sitting in the two-horse leading chariot escorted by two riders with running horses opening the way, followed by one rider in the middle. On the middle and the northern part hunting scenes are represented; all the figures seems in movement to the north. We can recognize nine groups of characters: a red-clad hunter riding a white horse and holding a bow in his left hand and pulling an arrow in the right hand to shoot two fleeing deers in the front; two riders riding shoulder by shoulder; a hunter in red riding a black horse, and pulling his bow to shoot a deer; a red-faced hunter in grey riding a dark brown horse; a hunter in green off the horseback to pick up the prey; a hunter riding a white horse, holding the rein in the left hand, and keeping the lash, to whip the horse forward at fast speed; a hunter in red running after a wild boar; a white-clad ride hunter holding a spear on the back on a white horse; a hunter dressed in yellow, riding a red horse, and shooting the prey over his back; other figures are mutilated and unrecognizable. In the lower part, the most damaged, the scenes are difficult to be understood and described. The only recognizable is another scene of chariot outgoing. The Han period marks the beginning of an imperial bureaucratic state, where the social status rests on on a rudimentary examination system and the growth of a land based aristocracy.5 - On the western wall, paintings in the north are striped off seriously. It is assumed that those paintings should be the scenes of musical and dancing performance. In the middle of the wall is the scene of rooster fighting. In the south of the wall is the banquet scene with dances; some characters are sitting on a wooden couch with a screen on the back; others are enjoing the show sitting on the floor; at the centre of the scene there are two dancers. The screen is a very important element during the Western Han period, but more generally in Chinese culture. It represents a division between the private part of rich houses and the representative space. During this period there was the first operation of imperial unity, in the sense of the continuity of a single dynastic house. Government was now more effective that ever been; cultural life was richer, with more frequent contacts with non-chinese people, a more sophisticated view of literature, and the embellishment of many of China’s arts and crafts. In this period the religion had formed an integral element in society and politics. The religious belief and practices of Han China are based on three major principles: that of the Five Phases, which regulated the cycles of growth, change and decay; that of the complementary forces of Yin and Yang; and that of the single overwriting presence of tao. Five Phases The term wu hsing is variously rendered as the ‘Five Phases’ or ‘Five Elements’ or ‘Five Agents’.6 In a 100 B.C. source it is said that the so called ‘Yellow Emperor’, Huang ti, who examined the movements of the stars, worked out their cycles and initiated the concept of the five phases that comprehend universal activity. The powers of the five elements became associated with materials (wood, metal, fire, water, earth) and other sets of objects or qualities that could be numbered in five, such as the colors (red, black, white, green and yellow) or the directions (south, north, west, east and center). The number five assumed a strong symbolism: there were five sacred mountains, five senses of human perception, five musical notes ect. Wu hsing were associated also with different animal symbols (green dragon at east, red bird at south, white tiger at west, serpent and turtle at north, no symbol at the 5 4 Loewe 1970: 72. 6 100 Ch’ü 1982. Loewe 2005: 38. 3D Cybermaps of Western Han Mural Tombs center). These animals marked the four seasons and four cardinal directions: the green dragon of the East (spring), the red bird of the South (summer), the white tiger of the West (autumn), and the black snake or tortoise of the North (winter). The fifth direction was the centre linked with no animal symbols.7 The four symbols appeared frequently as a decorative motif on the backs of mirrors, on porcelains and of roof tiles. It is important to notice that from the middle of the first century before Christ the Five Phases affected iconography. The four animals sometimes may be accompanied by what may be a fifth symbol, a mound. Yin-Yang According to one theory which was evolved at about 300 B.C., the creation of the world and the continued processes of nature were to be attributed to the complementary powers of two major forces of Yin and Yang. The different impact of these two forces could be recognized in the everyday phenomena of the world. Yin was associated with female, dark and cold, Yang with male, light and heat; and the rhythmical procession of natural phenomena depended on which of the two forces happened to be in the ascendant. Yin and Yang were manifested in types of energy or qualities, or the material elements of fire, water, metal, wood and earth, whose creation they had contrived but which were themselves powerful enough to ordain the form of the material world. Tao Tao is known in writings as the Tao-te ching and the Chuang-tzu as the rule that underliens the universe. Tao is also defined as the ‘way’, “is majestic, and brings into question the value of human assumptions, judgments and aspirations”.8 Tao theories had to be well known during Han Dynasty. According to Loewe, in a daoist school of thought the movements of nature had to be seen as advance and decline of Yang, followed by that of Yin, in a total of five phases (tab. 1). Yang Equilibrium rising growth maturity tranquillity wood fire earth green dragon red bird no symbol/ mound Yin rising growth metal white tiger maturity water snake/ tortoise Table 1. Schematic representation of daoist interpretation of the nature universal movement. Table elaborated from Loewe 1982: 38. 7 8 Loewe 1970: 118-121. Loewe 1982: 38-41; Loewe 2005: 43. To those who thought in terms of Five Phases and Yin and Yang, Tao was the order of nature within which those rhythms operated. Dynastic governments identified themselves to a colour and to an element as representative of its power. Han sovereignty was explained as representing the dominant element of water-black, or later earth-yellow, and the appropriate colours were chosen for ceremonial use and display. The yellow color became increasingly popular, so much so some emperors started to be named “Yellow Emperor”.9 Another important aspect of the Western Han ethical and philosophical system is the introduction of Confucianism as official imperial doctrine under the emperor Han Wudi (156-87 BC). The aim of Confucianism was the creation of a complex system of social and moral laws to end the Chinese spiritual decay. Confucianism focuses on the human experience and never on supernatural and metaphysic aspects. For this reason it was the imperial instrument for the organization of the chinese system of emperor and government. Moreover Confucius thought the importance of ritual and music in shaping moral sensibilities, and he advocated the benevolent sort of hierarchical social order. The idea was a society where everyone knew their position and acted in accordance with it: “Let the rulers be rulers, ministers be ministers, fathers fathers, sons sons”.10 He was convinced of filial piety as the base of a good society. According to Grant Hardy and Behenke Kinney, if Daoism is associated with individualism, freedom, non-conformity, nature, retirement, wit, and mysticism, Confucianism is associated with hirarchy, order, social responsbility, service, and conformity.11 At this period the Chinese society could be classified in emperor, officials and non-officials, organized in a pyramidal hierarchy (fig. 3). To be official meant to have one of the most important position in the hierarchy; officials were chosen originally in the base of hard qualifications, then more frequently thanks to sponsorship or favoritism.12 Also if lineage was not a requirement for the official career, the proximity to the central government, or good family connections, played a high role in shaping the official advancement. Officials were in charge of bureaucratic duties. They were divided in three main branches and this division dated back to the Quin Empire: civil, military, censorate.13 The senior office of the civil branch was the chancellor, the most powerful man in the administration, working directly with the emperor to evaluate reports and set policy. Under the chancellor there were nine ministers, head of government departments as that of ceremony, the palace, trials, palace gards, transport, state visits, the imperial clan, agriculture and the lesser treasury. 9 Khon 2005: 136-137. Analects, 12:11. 11 Hardy and Kinney 2005: 5-6. 12 Lowe 2006: 71-85. 13 Hardy and Kinney 2005: 31-33. 10 101 Cyber-Archaeology Riegl LMS Z390i. It permits an acquisition with an accuracy of 6 mm for a range of 1-400 m. This technology allows the digital acquisition of tridimensional objects, as point clouds. The resolution setted for the acquisition defines the density of the point cloud and the detail of the representation. Every point is described by a spatial position in x, y, z coordinates respect to the origin represented by the position of the scanner. The model obtained is characterized by high geometric resolution, that is fundamental for the correct interpretation of the structure. Figure 3. Western Han governmental structure. Elaboration from Hardy – Kinney 2005: 32. At the beginning of Han Dyasty (Western Han) one third of the empire was organized into fifteen commanderies, while the rest of the land was divided among the kings. However the number of kingdoms decreased in favour of new commanderies that became about eighty in total. Each commandery was divided in counties and was headed by a civil governor and a military commandant. During the Han Dynasty the cult of immortality was also important and it influenced religious practices. The world of the immortals is sometimes depicted in the fresco paintings of Han tombs. The Yuren, a celestial being partly human partly animal, was considered the spirit who leads the dead to ascend to heaven for immortal life. The desire to prolong life was not just linked to an individualistic conception of life, but to the desire of ensuring lineage and community continuity or survival. There were both the desire of a physical immortality and the conviction that was possible to obtain the bliss in a non-worldly immortality; the latter was proper of ascetics and hermits.14 Both the definition of this complex political and social system and the diffusion of Confucianism in the Western Han Dynasty could have brought about the introduction of scenes of daily life in the tombs. They could be read representing the social status of the tomb master. F.G., P.D.G. 5. Fieldwork and post-processing: from the 3D datacollection to the 3D modelling Fieldwork and 3D data-collection The 3D data collection of M 27 was realized through laser scanning. The laser scanner used for the project was the 14 Loewe 1970: 114. The data acquisition plan is the most important step during the fieldwork. It is fudamental to choose the level of detail in advance, while planning for the result of the final data output. The 3D data capturing during the fieldwork depends, in fact, on the final project purpose. A project finalized to the fruition of the 3D models in a virtual reality environment, for instance, requires the optimization and pre-processing of the high resolution models. A high number of polygons could decrease the virtual reality engine performances, because they work on a real-time calculation and loading of the model polygons. The M 27 3D relief is strictly connected to the Western Han Dynasty Virtual Museum project. The 3D data collection of this tomb was realized with a high level of detail (8 mm), even if the final goal of the project, the fruition in a virtual reality environment, doesn’t necessarily need a such a detailed acquisition. This choice is strictly connected with the huge preservation problems linked to this heritage at risk. According to these arguments our project his necessarily focused on two different research lines: if on one side we are working on communication of data in a collaborative virtual environment, on the other side we can’t loose sight of the preservation value of an accurate 3D digital survey, and this in accordance with the so called CASPAR project (Cultural, Artistic and Scientific knowledge for Preservation, Access and Retrieval). This is a largescale pilot scheme focused on the implementation of a pioneering framework to support the end-to-end preservation lifecycle for digital information based on existing and emerging standards.15 In other words, the aim of this international project is the creation of a huge archive of digital data, collected for preservation purposes all over the world. It will provide information to scientists and permit the consultation and the scientific analysys of a library of different kinds of data in real time on the web. Even if this project is currently in its embryonic phase, it is very important to start thinking about this new way to preserve information, decreasing the loss of world heritage. 15 http://www.unesco.org/science/remotesensing/?id_page=98 &lang=en 102 3D Cybermaps of Western Han Mural Tombs Post-processing and 3D modelling The first step of the elaboration process of M 27 point clouds was the filtering. In order to obtain reliable 3D models the smoothing of point clouds is fundamental. It is necessary to smooth point cloud data in reverse engineering, or the inspection of free-form surfaces, because noisy points will have a negative influence on the post-processing of this data.16 Different kinds of filtering were applyed (filter noise, filter redundancy, smooth points, sample points), without losing sight of the metric accuracy of the final 3D model. The following step was the point clouds triangulation. This is a very delicate operation, whose success depends on the acquired data quality. In our case it was necessary to process two different point clouds on the basis of the project needs: the first one at high resolution was realized to archive the data for a preservation purpose. The second one was processed considering the data communication; in this case it was necessary to optimize the point cloud before triagulating it. This process allowed the creation of a 3D model with a controlled polygons number, an ideal solution to increase the virtual reality engine performances. The digital model was texturized using different maps, in order to provide different levels of perception. The first texture was obtained by the high resolution pictures of the tomb. It is a georeferenced map coming from different photo captures of the tomb frescos. The images were applied on the surfaces of the objects using 3dsMax “unwrap modifier”, which is a special tool of mapping, which permits to apply the image directly on the mesh. With this technique it is possible to link the plain of projection to the position of the digital camera.17 In order to provide a second level of interpretation and perception, a graphic reconstuction of the fresco was realized using the drawings done by the archaeologists, georeferencing them on the regular texture. The final level is the overlapping of the regular texture with the drawings. Different 3D model outputs were realized for the Xi’an University of Technology Western Han Mural Tomb. The first one was a 3D short movie in computer graphics, able to explain the structure, the frescos, and all related iconographies. Finally the tomb was imported in a virtual reality system using an open source engine (Open Source 3D Graphics Engine). F.G., N.D. 6. The cybermap State of art The M27 mural paintings contain a very complex 16 17 Xue-Chang Zhang et alii 2006. Galeazzi et alii 2008: 133-136. interpretation code, which shows the relations between life and death during the Western Han dynasty. Both the simple description of the subjects, and the 3D virtual reconstruction of the tomb, are insufficient for approaching a correct cultural interpretation. In this paper we present a preliminary study on the reconstruction of semantics of the tomb’s iconography, obtained through a 3D virtual cybermap. The cybermap (or hypertextual map in three dimensions) is the graphic layout of a set of relations between each scene and its context. Interacting with it, users are able to acquire as more information as possible on the tomb iconographic apparatus. A cybermap could be also defined as a mindmap, since it is the geometric translation of a mindscape.18 Thanks to an abstract code it is possible to represent a symbolic environment, using different kinds of metadata. The first cybermap was realized in 2001, as part of the Scrovegni Chapel Virtual Reality Project.19 This chapel is located in the city of Padua (North Italy), and is one of the most important masterpieces of the European art. It was painted by Giotto between 1303 and 1305 and commissioned by Enrico Scrovegni. The paintings were restored in 2002, because of serious problems of preservation; but the accessibility to the monument is still limited in numbers of visitors (twenty persons) and in visit lenght (fifteen minutes). Therefore a Virtual Reality System was needed for improving on the musealization and the understanding of the monument. The paintings represent stories of the Virgin and Jesus Christ, and the Final Judgment, all organized in registers over the walls. The map was designed to show the spatial relations between scenes and the thematisms which they were linked to: 1. themes concerning the general meanings and the paintings symbolic contents (thematic reading, exegetical reading, reading according to the lighting of the walls); 2. themes concerning the pictorial style (the light, the colour, the composition, the space).20 Narratives and maps In the case of our tomb, a cybermap make-up was felt to be more challenging because of the complexity of contents. The idea of this work originates from the fieldwork. Visiting the monument we immediately understood that there was a big difference in the conception and use of space for the realization. As previously stated, the paintings are realized on a white clay stratus which hides the material support, giving the sense of an immaterial whole with intangible boundaries: contents and frescos spatial relations. We can argue that an understanding of the tomb contents is possible just showing that intangible boundaries. 18 “The mindscape is a virtual landscape perceived and interpreted by mental maps”; Forte 2002: 95-108. 19 Forte et alii 2002: 43-52. 20 Ibid.: 5-6. 103 Cyber-Archaeology Through a simulation process the potential semantic re-composition of the tomb creates new metaphors of learning and communication. The iconographic complexity of the tomb frescos needs a cybernetic approach that could permit the decoding of the single representations and their pragmatic relations. Thanks to the cybermap it is possible to underline the strong symbolism that springs from the scenes. The tomb is the logic and practice result of the revolutionary historical moment in which it was built -the end of the Western Han Dynasty-, and its paintings partially narrate and describe this period. They are visual narratives composed by scenes and themes. It is well known that the human brain responds directly to the inability to process all the visual elements of a scene simoultaneously. As our eyes move from one point to another, they recreate a continous narrative that is perceived by the brain as seameless whole.21 According to this statement the cybermap acquires an added value. It guides visitors in a virtual tour, showing the main iconographic themes paths; therefore it helps people to recreate narratives, moving from one scene to another in the right sequence. We should think of human consciousness as emerging from the complexity of such optical narratives through cause-and-effect-models, graphs and timelines. For a century, the dominant view of the brain has been that of a simple “reflexive” organ. In this view, human brains are little more than input-output machines. But it has been demonstrated that neurons don’t simply wait for incoming data to be activeted. They are always active and choose whether and how to respond to stimuli.22 John J. Ratey argues that the brain is: “a powerful prediction machine, continously making elaborate mental maps of the world that are reliable enough to enable us to predict what lies ahead, both in space and in time”.23 If the material monument represents the tangible remain of Western Han heritage, the frescos spatial relations are traces of its intangible one. The map schematizes the themes and simplifies the information. Scenes, themes and paths The spatial analysis of frescos in M27 permitted to underline their semantic value, but also to understand the monument pragmatics. The scenes described before are connected to four main themes: Daily life (fig. 3a): as already said, this theme is rarely present in late Western Han tomb. It symbolizes the social 21 This idea was developed by Vik Muniz in the exibition “Rebus” at the New York MOMA museum. He arranged art and design objects from the MOMA’s collection in a special order, and asked visitors to create a narrative from these artifacts. http://www.moma.org/visit/calendar/exhibitions/304. 22 Ratey 2002: 110-114. 23 Ibid.: 112. status of the owner, and testifies the introduction of Confucianism as official imperial doctrine. The scenes are also symbols of earth and mortality. They are painted in the two lateral walls of the tomb. The path starts from the eastern wall (representing daily activities) and continues to the opposite (representing nightly activities). Ascension to heaven (fig. 3b): the core of this theme is the Northern wall (opposite to the entrance), where the yuren stands waiting for the deseased for the immortal life transfer. The yuren is the means of this transfer. The trip symbolically starts from the entrance where, on the two sides, are guardians animals (tiger and dragon) defending the sacred place from intruders. It continues with the daily life scenes, then with yuren on the northern wall, and ends on the ceiling where the heaven is represented. Five Phases (fig. 4a): this path is designed on the ceiling, where the red bird, green dragon, black snake, white tiger, design a map themselves, being symbols of cardinal points. The path shape is circular, and it describes a continuous movement, defining a circular conception of time (eternal repetition). Yin and Yang (fig. 4b): following this path the tomb can be devided in two triangles, where the verteces are cardinal points: the South-East/North-East/South-West triangle represents the yang (light, male, day); the South-West/ North-West/ south east triangle represents the yin (dark, female, night). This idea is reinforced by an observation: as already described, the green dragon of the east is painted in direct relation with the sun, and the white tiger with the moon. While the red bird and the snake are perfectly at north and south, the east and west symbols are designed at the two opposite corners South-East and North-West. Why this anomaly? We don’t have any certain answer to this question. We discussed a lot with Chinese archaeologists we are collaborating with, and the question is still open. We would just propose a suggestion: that the position at the corners of the two symbolic animals, the sun, and the moon, is not accidental. We tried to superimpose a symbol of Tao to an unwrapped image of the frescos and we saw that the location of that elements can suggest the background of this philosophical symbol, also if it appears later in time. We shouldn’t forget that the creation of a symbol is just the final, graphic result of a cultural process. In the 3D reconstruction we translated every scene in a simple object (a cube), created 3D connections between scenes, and assigned a colour to each theme. Contents communication and learning process The cybermap has been presented in a short-movie as part of a more complex process of contents layout. In a movie of three minutes we decided to “musealize” the tomb, showing different layers of perception. In other words we started the movie with the simple 3D reconstruction of the tomb; then we showed the tomb model texturized using the paintings drawings made by archaeologists; in 104 3D Cybermaps of Western Han Mural Tombs a third step we overlapped the drawings to the texture of actual paintings, adding the cyber map; finally we reproposed the original 3D model (fig. 5). We conceived every layer as a cognitive model which helps the users to have added knowledge on the object. The viewer should be able to collect the information, step by step, and to retain it. The idea to end the movie with the simple 3D recostruction is based on the convintion that the user can recreate the fresco contents using information previously collected from the cybermap. The human brain collects information thanks to mirror neurons. They are premotor neurons discovered in a sector of the posterior paretial cortex, that permit to map observed, implied, or heard goal-directed motor acts on their neural substrate in the observer’s motor system; they also allow a direct form of action understanding, through a mechanism of embodied simulation.24 Through mirror neurons, the user is able to retain the map information and is able to mentally locate it in the original position in the 3D space. In this way it will be possible for the visitor of the virtual tomb to enjoy the paintings without any graphic (cybermap, drawings overlapped to the texture) obstacle, but with a new knowledge, previously acquired. Figure 4. Themes: a. Daily life; b. Ascension to heaven. As already said, we are working on a complex system that includes meta-data. As a final result the cybermap will become interactive. It will be possible to link every cube to metadata, activating the learning process through affordances. According to Gibson the affordance is the quality of an object or an environment allowing individuals to perform an action25; “affordance consists in the opportunities for interaction that things in the environment possess, relative to the sensorimotor capacities of the animal”.26 They are stimuli for the brain to activate a learning process. P.D.G., F.G. 7. Conclusions In the Xi’anUniversity of Technology Mural Tomb case study a new methodology was tested, with a focus on the creation of new parameters in the archeological and communication field. The possibility to use new technological tools today, forces scholars to re-think and rearrange the old way to make archaeological documentation and musealization. Starting from the 3D data collection on the fieldwork, and concluding with the creation of a 3D cyber map, we tried to explain the added values of this new approach. We think that increasing the number of perception level of heritage through technologies, it is possible to improve the user capacity to collect information, retain it and transform it in knowledge, Figure 5. Themes: a. Five Phases; b. Yin and Yang. 24 Gallese 2009: 521. Gibson 1979. 26 Varela et alii 1991: 91. 25 105 Cyber-Archaeology Figure 6. The four levels of perception of the tomb. after a subjective interpretation. As already said, the output of this work has been a short movie were the perception levels were combined with the cybermap. The learning process linked to this approach can be described as an hybrid learning in between symbolic reconstructive and sensory-motor. According to Antinucci27 the symbolicreconstructive way to learn is based on textuals that are conceived as symbols. The user reads, decodes textual symbols, and eventually recreates in mind a visual idea from the textual description. In the sensory-motor learning process, he/she learns through perception and action on the reality; users perceive an event with senses, acts on objects and changes the perception on the event after the action. This second process is augmentative: the action can be seen as a cause producing an effect, which is a new action. If the short movie urges people to utilize senses, the absence of interaction avoid a full sensorymotor learning. The latter is the core of an immersive experience. The final aim of the project will be the creation of an immersive collaborative environment, where the cybermap will be interactive and linked to metadata such as visuals, images, textuals and videos. The idea is close to that realized in the Virtual Museum of the Villa of Livia. This museum is exposed inside the National Museum of Rome, and it is the virtual reconstruction of Augustus wife’s villa (first century A.D.). It has been conceived as a virtual collaborative environment, where visitors can 27 Antinucci 2004a: 17; Antinucci 2004b. interact with the system, but also share information between them. They can visit the virtual, choosing an avatar that represents them in the 3D space. In conclusion this research stemmed from two queries: can 3D data-collection increase the preservation capacities of our cultural heritage? Can digital data ameliorate the communication and the learning process in the museum, and how? With this reaserch it has been proved that an high resolution data capture has a huge potential for preserving heritage at risk. However the 3D model alone is not enough to show the original context of an ancient monument. Every archeological site, every museum need an infastructure for the general public. At the same time a virtual environment needs digital tools for users in order to understand ancient codes and be able to reconstruct the context in every monument (fig. 6). F.G., P.D.G., N.D. Acknowledgements Special thanks are due to Xi’an Jaotong University in the person of Li Jiajun, Gong Yenyin and Li Wen. Special thanks are also due to the Xi’an Municipal Institute of Cultural Relics Conservation and Archaeology in the person of Cheng Linquan, Guo Yongqi, Zhang Xiangyu, Shao Zhenyu, Yang Yonggang; and to the Xi’an ICOMOS in the person of 106 3D Cybermaps of Western Han Mural Tombs Figure 7. Hybrid representation of the tomb paintings. Sun Fuxi. To professor Li Jiajun and doctor Cheng Linquan especially we owe acknoledgements, because of their scientific advise on our research, and for sharing their knowledge and all the material collected in the fieldwork. We are thankful to Lizhi Zhang, in art Abby, for her efficiency, kindness, help in any kind of situation. Thanks to her we felt China as our country. We are also grateful to Mandy Chan, an incredible young and bright researcher, with the hope of future collaborations. 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