Experiencing the Past: Computer Graphics in Archaeology (Digital Imaging) Part 3

Temenos and Room III

The sacred area represented by the central part of the acropolis, during the eighth century BC, was partially enclosed by a low and wide precinct wall of eccentric shape, a Temenos, well preserved along the eastern and northern slopes. It was made with stone blocks in double curtain technique (emplecton), with a constant width of 1.50 to 2.50 m. Totally obliterated on the western and southern sides, as a result of the slip of land and weather agency, it probably included a monumental entrance on the north side in front of building A, as shown by the particular bend of the wall and the construction technique of its northern limit. It is not excluded that a second main entrance could also be located to the south, where the circuit wall was damaged by building works and additional changes of later period. Another modification was the adjunction of a small rectangular ambient, later in chronology, Room III, partially built and excavated inside the Temenos, along its east side (Figures 1.11(c), 1.13(e), 1.13(f)).

Precinct F, East House, Temenos House

Research on the central part of the acropolis revealed a large and low rectangular precinct of 8.30 x 5.60 m, called Precint F (Recinto F) that contained traces of animal sacrifices, feasting activities, and pottery depositions that could be dated to the sixth century BC. The excavation of the Temenos and of the area east and north east of it, led to the discovery of a residential quarter represented by two houses, dated back to the end of the fifth century BC, namely the Temenos House (la Casa del Temenos), adjacent to the Temenos wall, and the East House (la Casa Est), in a smooth plain in eastern slope (Figure 1.13). The two buildings reflect the construction techniques of Greek Sicily and have such characteristics that they can be intended as part of a workshop district still partially unrevealed. The Temenos House (Figures 1.13(c), 1.13(d)), with a total length of 14.50 x 6 m, is adjacent to the exterior part the Temenos wall. The house consists of four rooms, with entrances to the east, and of an open area paved with cobblestones, on the north side. The construction technique shows large rectangular blocks with two courses and a flat roof with tiles. Within the rooms, rolled on the floor by the collapse of the ceiling, was found sets of pottery and objects, such as between transport amphorae, tablewares, cooking pots and storing jars, and especially some large mortars for grinding olives. Approximately 25 m northwest of the Temenos House was identified the second complex of the East House (Figures 1.11(e), 1.13(a), 1.13(b)), with an area of 10 x 2.50 m; it was built using the steep slope of the mountain in this area, using the rock as rear wall. It has the same kind of flat tiled roof and was accessible via a five step scale, located on the north side. Of the entire building just two connecting rooms were highlighted, the rectangular room A, to the south, 2.80 x 2.00, and a trapezoid room B 7.20 m long. Inside room A above the floor, many bronze arrowheads and large storing jars, amphoras, common wares, and mortars were found.


The Virtual Acropolis and the Multilayered 3D Model

The technique of 3D modeling in the case of the acropolis of Polizzello gave two completely innovative and extremely significant achievement, to augment the cognitive ability of the archaeologist: the promoting of an archaeological site and the monitoring of its conditions of degradation. Because of logistical problems, the Acropolis archaeological park will remain closed to the public for several years. Moreover some of the buildings (actual conditions of the site are shown in Figure 1.11), the oldest discovered in the exploration, were buried and not yet brought to light, so it was decided to create a virtual version of all the buildings of the acropolis in the same preservation conditions as at the time of the discovery. The “virtual acropolis,” thus, allows the experience of visiting an interactive and immersive 3D environments.

The second result is to overcome all the traditional documentation methods of the many phases and chronological stages of a multilayered site like this, through color plant phase, with the creation of a multilayered 3D model, where all monumental evidences are organized into four temporal phases that summarize the history of the site between the eighth and the fourth century BC (Figure 1.14). In this way it’s possible to focus better on the detailed planimetric evolution of the sanctuary between the eighth and sixth centuries BC and highlight the major functional difference of the last phase of the fourth century, that was only residential. With this methodology the overall development could be integrated with the architectural features of a single building, like building E, which itself has undergone many complex transformations. Finally, only for the last phase, for which the evidence revealed during the excavation was particularly significant, it has been possible to propose 3D models of how original buildings had to be, even on the basis of other evidence known from contemporary and historical sources, both for what concerns the structural data, the pottery, and objects that were used in everyday life.

Digital Restoration

The technique of 3D digital restoration of archaeological objects is perhaps the most common trend in interdisciplinary projects related to the interpretation and dissemination of archaeological knowledge. This is because of the potential that 3D has in subtracting the archaeological goods to the destructive effects of atmospheric agents, of pollution, of time, and, in some cases, of natural disasters and wars. The digital restoration is not only aimed to keep the archaeological goods from future risks, it is also suitable to return the conceptual and artistic integrity to monuments or complex objects, which in antiquity were considered as a unit and nowadays, for different reasons, are disassembled and divided between museums of different countries (a well known example is the complex of Parthenon sculptures [75]). It is also the chance to produce three-dimensional snapshots of specific phases of past life on the basis of the historical documentation of a monument [76]. The digital restoration is also the virtual version of the physical restoration, which for practical or economic reasons can not be made [77], which aims to give back a true image of a fragmented reality and, in some cases, wrongly recomposed [78]. In the last decade, in all the projects of digital archeology and also of 3D digital restoration, the reverse engineering approach had a large application in the policies of promotion of cultural goods [79-82,82]. The high-definition 3D laser scanner is an instrument that collects 3D data from a given surface or object in a systematic, automated manner, at a relatively high rate, in near real time using a laser ray to establish the surface coordinates.


(a) East House, virtual replica; (b) East House, 3D re-constructive model; (c) Temenos House, virtual replica (d) Temenos House, 3D re-constructive model; (e) Room III; (f) Room III 3D re-constructive model.

FIGURE 1.13

(a) East House, virtual replica; (b) East House, 3D re-constructive model; (c) Temenos House, virtual replica (d) Temenos House, 3D re-constructive model; (e) Room III; (f) Room III 3D re-constructive model.

Multilayered 3D model of the Polizzello Acropolis: (a) phase I, half of the eighth century BC; (b) phase II, from the half of seventh to the beginning of sixth century BC; (c) phase III, end of sixth century BC; (d) phase IV, between the end of fifth and the beginning of fourth century BC.

FIGURE 1.14

Multilayered 3D model of the Polizzello Acropolis: (a) phase I, half of the eighth century BC; (b) phase II, from the half of seventh to the beginning of sixth century BC; (c) phase III, end of sixth century BC; (d) phase IV, between the end of fifth and the beginning of fourth century BC.

From a decade, this technology has been applied to archaeological research to construct geometric models with different characteristics [83,84]. Most archaeological work has been carried out to digitize objects of an intermediate size, such as settlement structures, statues, and vessels. The most recent works have been focused on modeling structures during the excavation of archaeological sites, either of only one zone [11] or the complete ensemble [85]. These studies have been carried out from the ground surface or using helicopter and airplanes [86]. Traditional methods such as tapes and theodolites, and more modern technology such as total stations and GPS, provide accurate but relatively slow methods for gathering spatial data, and their use to scan small objects is not feasible.

The possibility to obtain in a limited amount of time a virtual exact replica of reality makes the laser scanning method ideal for studies of 3D digital restoration, where the virtual recomposition of fragmented elements, both physically and narratively, is fundamental [88]. The Archeomatica Project team of researchers in this field has proposed integrating the Blender-based 3D modeling and image-based 3D modeling with the laser scanning technique, in order to solve the possible data voids problems connected with complex scanning. The laser scanner hardware used is the relatively cheap Next Engine [89]. The choice was based essentially on the fact that it is very compact and handy, and then it proves to be very versatile especially when the objects to be scanned are placed in restricted spaces or cannot be removed. The case studies to test the 3D digital restoration, presented below, were chosen because they presented different levels of difficulty but also to demonstrate how the application of this technique has offered several new elements for the interpretation of objects and, sometimes, of their contexts.

Minoan Model

A good example of research in which 3D graphics techniques are applied to the problem of fragmentation is represented by an enigmatic small clay model, only partially preserved, from the site of Phaistos in Crete (Figure 1.15(a)), dating from the mid-fourth millennium BC (Early Minoan I-II in terms of Minoan chronology). The model was recovered in the south east room of the so-called Western Bastion, located on the northwestern side of Piazzale I [90]. A recent analysis of the piece [91], long known but ignored as incomprehensible at first glance because of its poor state, has led to its interpretation as a figurative scene of a religious nature. This interpretation was supported by its digital restoration the experts of Archeomatica Project have carried out. Basing on the conservation status of the object, it was possible to suggest the presence of two distinct anthropomorphic figurines, which body and long arms with large hands were stretched on the ground, and of a couple of cylindrical objects in front of the figurines (Figure 1.15(c)). The good level of knowledge achieved in the field of Minoan religion, and the several iconographical comparisons also present in other classes of artifacts, has led scholars to interpret the scene represented by the model as a scene of adoration of betili, large phallic stone symbols considered as bearers of good fortune, by two female figures in accordance with the custom of the Minoan religion [92]. This insight was made explicit through the creation of a 3D model, basing for the iconography of the female figures missing, the well known statue of the goddess of Myrtos [93], which is contemporary to the Phaistos model.

Asclepius

Another application of 3D digital laser scanning was the restoration of a colossal marble bust of the god Asclepius (Figure 1.16(a)) with an inscription [94], probably a copy of the I-II century AD of a late Hellenistic original and commonly considered one of the most representative pieces of the collection of Roman statuary of the Archaeological Museum “Paolo Orsi” of Syracuse [95-97]. The statue, 154 cm high, 90 cm wide, and 37 cm deep, kept for two fragments reassembled of torso and head, was found during the excavation of the foundations of the Spanish fortifications of Ortigia, around the mid-sixteenth century. Kept until 1810 in the Castle Maniace, the main Spanish fortress of Syracuse [98-100] and known also as “Don Marmoreo,” the statue of the god was re-utilized within the castle with radical changes, which altered the iconography, and probably it was placed in a niche or fixed to a wall, as evidenced by the work of chipping and smoothing performed on the back. These changes implied the engraving on his chest of a commemorative inscription in Spanish (Figure 1.17(a)), which remembers the granting of King Philip III to the noble ruler of the castle, John Rosa, of dedicating, on 20 July 1618, the whole castle to St. James, and the four corner towers to patron saints St. Peter, St. Catherine, St. Philip, St. Lucia, and the granting of the guns firing blanks at the feast of the patron [95]. The epigraph is especially known for its transcripts made by scholars of the last century. At present due to the deterioration of marble surfaces the inscription is almost illegible.

(a) Early Minoan clay model from Phaistos; (b) digital reintegration of the virtual model; (c) virtual version of the clay model.

FIGURE 1.15

(a) Early Minoan clay model from Phaistos; (b) digital reintegration of the virtual model; (c) virtual version of the clay model.

The statue of the Castle Maniace brings with it many issues of historical and archaeological heritage, including the iconographical interpretation, the hypothesis of the presence of a cult of Asclepius at Syracuse, the location of the temple which originally housed the statue, and the type of alteration carried out in the Spanish ages. Although there was no recognizable signs on the statue of the iconography of the god of medicine, son of Apollo, nor the caduceus and the serpent, and although the beard and thick curly hair recall many canonical representations of divine brothers Zeus, Hades, and Poseidon, a careful examination of certain stylistic features, such as facial lines and strophion over his head, suggest a comparison with the statue of Asclepius of Mounichia, built in the second century BC for the Asklepieion of Piraeus, and now kept in the National Museum of Athens [96]. Chronologically closer is also the Roman Aesculapius of Villa Torlonia, of the first imperial age, which shows the bearded god standing with caduceus, half naked, covered by an himation supported by a prop [101]. The great reputation that the worship of God in the Greek world had [102,103], which devotion continued to the Roman Aesculapius, and the widespread presence of his sanctuary in Sicily, often characterized by large architectural complexes as Agrigento [104] and Eloro [105], all suggest that Syracuse, primate of the Western Greek city, was home for an Asklepieion. Among the references of the literary sources, first of all is the quotation of Cicero in the oration in Verrem (57.127-128) about the robbery made by Gaius Licinius Verres, propraetor of Sicily from 73 to 71 BC, accused of the theft of a statue of Apollo Paian from the temple of Asclepius at Syracuse. Moreover, the hypothesis that Asklepieion of Syracuse had its own place in Ortigia, as the discovery of the statue Castle Maniace Asclepius would suggest, is further strengthened by the discovery of a statue of Igea, daughter of Asclepius and associated for worship to the father as a god of salvation, in the excavations of Piazza Pancali [106], and of an honorary inscription dedicated to the city by a doctor found in the excavations of Corso Matteotti, probably, placed inside a sanctuary area [107]. After the discovery by the Spanish, during his transfer to the Castle Maniace, because of its large size, the statue probably had to be cut into separate blocks. In fact it is possible to see clearly the horizontal cuts at the neck, head, and half lower torso. On that occasion, were also likely to be selected only those parts necessary to build a herma, which suitably amended, was then relocated in the architecture of the castle.

(a)    Marble statue of Roman Republic period depicting the god Asclepius, from Syracuse Museum; (b)    3D model of the statue obtained with laser scanning technique.

FIGURE 1.16

(a)    Marble statue of Roman Republic period depicting the god Asclepius, from Syracuse Museum;

(b)    3D model of the statue obtained with laser scanning technique.

The decision to produce a 3D model of the statue of Asclepius, using a laser scanner and improving the results with the 3D modeling during data processing, had two aims. First it was useful for increasing the knowledge about the artifact, investigating in detail the signs of ancient and modern working in order to correctly identify and distinguish the stylistic archetype, the changes made by the Spanish, and the restoring of the last century. Second, the creation of a virtual replica of the statue is a strong incentive for the promotion on multimedia, computer, and web totem, of this very fragile archaeological good, not suitable to be moved for exhibitions and cultural events. The 3D model of Asclepius was obtained by the technique of laser scanning, with a deliberate use, in this case, of an optical triangulation scanner rather than a time of flight (Figure 1.16(b)). The maneuverable and small scanner NextEngine has proved very useful for scanning the torso of Asclepius, as the statue, nontransferable elsewhere for the scan, was located very close to the wall of the exhibition hall of the museum, a fact that left little leeway to the operators of the laser scanner, allowing to capture correctly most of the details, leaving a small void area on the shoulder, extremely complex to acquire, and the back. Specific study of the result of 3D scanning and data processing has revealed some very significant changes to the original conditions of the statue. It is clear that the left deltoid has been removed as the upper left chest and lower abdominal part has been carved and smoothed. These operations, invisible to a simple analysis, should be interpreted as a conscious elimination of the drapery of his dress, which occurs constantly in the canonical representations of the god, in order to make the statue more symmetrical when, during the Spanish time, it became an inscribed herma (Figure 1.17(b)). It was also possible to observe how the reassembly of the head with the torso was a mistake that led to the anomalous downward inclination and slight twist to the left, unusual in ancient iconography, and probably due to incorrect restoration of the last century. The optimization of the graphics gave a much more precise transcription of the engraved inscription. The work on the statue of the god Asclepius of Syracuse, however, is still a work in progress. In the future the research will include both the possibility of developing the model obtained to remove the erroneous restoration and attempts to bring back, based on stylistic evidence, the original iconography with which the god was represented before the Spanish era changes, also dealing with polychrome details, where these are documented.

(a) Detail of the Spanish inscription on the chest of the Asclepius statue; (b) enhanced version of the inscription on the 3D model.

FIGURE 1.17

(a) Detail of the Spanish inscription on the chest of the Asclepius statue; (b) enhanced version of the inscription on the 3D model.

Next post:

Previous post: