“Sacra Tharrhica Project”: Preliminary Results of 3D Virtual Reconstruction of the Punic-Roman Sacred Areas of Tharros, Sardinia

: The “Sacra Tharrhica Project” was started by the University of Bologna in cooperation with the University of Cagliari in 2017. The aim is to obtain a 3D virtual reconstruction of all temple structures of the Punic settlement of Tharros on the central west coast of Sardinia, starting from a systematic architectural and archaeological study of the Punic and Roman phases of the buildings. The project has firstly focused on the “Monumental Temple” or “Doric half-columns Temple”. This Punic sacred area was probably monumentalized between the late 4 th and 3 rd centuries B.C. After the Roman conquest, it was rebuilt between the 1 st century B.C. and the 1 st century A.D.


Introduction
The Punic-Roman site of Tharros1 is located on the central west coast of Sardinia ( Fig. 1 a), between San Giovanni hill, Su Murru Mannu hill, and the Oristano Gulf coastline (Fig. 1 b). The site was systematically excavated between 1956 and 1964 by the Archaeological Superintendent of Sardinia, Gennaro Pesce (Pesce, 1966). Subsequently, annual archaeological campaigns were conducted in the area of Su Murru Mannu hill by the Alma Mater Studiorum -University of Bologna, CNR (Centro di Studio per la Civiltà fenicia e punica) and the Archaeological Superintendence of Cagliari and Oristano until 1998 (Bultrini et al., 2000)2. In addition, in recent years the archaeological fieldwork resumed in the northern necropolis by University of Cagliari (Del Vais, 2017 and previous bibliography) and in the southern necropolis by the Alma Mater Studiorum -University of Bologna (Fariselli, 2013;Secci, 2014Secci, -2015Fariselli, Silani, & Vandini, 2017;Fariselli, 2018), and this is still ongoing. In particular, the sacred areas of the site were discovered since 1958 (Barreca, 1958;Pesce, 1961Pesce, , 1966Marano, 2014;Floris, 2014Floris, -2015Floris, , 2016Marano, in press) and study of them has continued until now through analysis of the historic documents and through new archaeological fieldwork activities3 (Acquaro, 1983(Acquaro, , 1991Floris, 2014Floris, -2015Fariselli, Boschi, & Silani, 2016;Floris, 2016). Because of the reuse of Punic buildings in Roman period and Late Antiquity and the considerable dismantling after the abandonment of the city about 1000 A.D., it has been difficult to achieve complete knowledge of these structures so far. For this reason, the "Sacra Tharrhica Project" was started in 2017 by the Departments of Cultural Heritage-DBC and History and Cultures-DiSCi of the Alma Mater Studiorum -University of Bologna (Coordinators: A. C. Fariselli, E. Giorgi, R. Secci, M. Silani) in cooperation with University of Cagliari (Coordinator C. Del Vais). The aim of the project is to obtain a 3D virtual reconstruction of all temple structures of Tharros4, for supporting a new systematic architectural and archaeological study of each phase. Achieving an exhaustive architectural re-reading of the Punic phase is one of the aims of the "Sacra Tharrhica Project" and a review of the data in the light of the new methodologies available is in progress.
The project has firstly focused on the sacred area known as "Monumental Temple" or "Doric halfcolumns Temple" (Figs. 2-3), located in the central area of the site. The sacred building is located South of the decumanus maximus, North of "Court Temple of Semitic type", West of the street leading from Bath n. 1 to Bath n. 2 and East of areas nn. 39-53 (Fig. 2). The area under consideration was probably enclosed by a street along the southern side, where part of a sewer is preserved; the western side, instead, shows some walls and two cisterns, so that a street was probably only in the South-West corner, allowing movement into the southern part of the adjacent sector (Marano, 2018, in press).

The "Monumental Temple" from Punic to Roman Era: A Diachronic Overview
According to traditional reconstructions, the "Monumental Temple" underwent three building phases (Pesce, 1961;Acquaro, 1991;most recently Floris, 2014most recently Floris, -2015. In its first phase, dating from the beginning of the Middle Punic Age (480-300 B.C.)5, the core of the sacred area was a natural rocky spur encircled by a temenos of large squared stones. The upper surface of the rocky core was carved by an uneven series of funnel-shaped holes interpreted as cupulae for receiving ritual or votive offerings (Pesce, 1961, pp. 340-343). In the second phase, dated in the 4 th -3 rd centuries B.C., the rocky core was carved into a platform with an access ramp and decorated with shafts of a Doric pseudo-portico crowned by an Egyptian gorge cornice on the three sides (Pesce, 1961, pp. 343-402;Acquaro, 1991). The platform was the support for an Egyptian style aedicula according to Gennaro Pesce (Pesce, 1961, pp. 390-395, grafico XIII) (Fig. 4 a) or an altar according to Enrico Acquaro (Acquaro, 1991, p. 549, fig. 8)6 ( Fig. 4 b). Between the 1 st century B.C. and the 1 st century A.D., the previous Punic temple was dismantled and its architectural elements were reused in the foundations of the new Roman temple (Fig. 5 a). According to Pesce, the area was organized like a sacred "labyrinth" with an altar in the middle and a small prostyle temple built on the quadrilateral structure erected at the base of the Punic temple ramp (Pesce, 1961, pp. 402-419) Based on the review of both Pesce's edited and unpublished archive data, a new hypothesis of reconstruction of the structural restoration of the temple known from the Roman period has recently been proposed (Floris, 2014(Floris, -2015. According to this reading, a new structure erected in the Roman Era followed the limits of the previous Punic Temple. A Doric capital and two large Egyptian gorges found inside the Roman cistern testify that the new building retained its hybrid architectural style, as shown in 5 See Maraoui Telmini, et al. (2014, pp. 116-117, Fariselli (2018, p. 115). For the possibility that the well-known inscription from Tharros celebrating some architectural interventions in the temple of Melqart in Qrtḥdšt -probably the same Tharros -may refer to the second building phase of the "Monumental Temple" see most recently Fariselli (2018, pp. 110-118), with updated bibliography. 7 A more recent hypothesis proposed by Dolores Tomei accepted Pesce's idea that a small prostyle temple was erected on the quadrilateral structure but proposed that the area was arranged as an "artificial wood", proposing to identify the third phase building with the templum dedicated by the disp(ensator) of Fundan(ia) Galla, whose construction and inauguration are mentioned in an epigraph from Tharros (Tomei, 2008, p. 126).

Methods
The preliminary phase of the fieldwork concerned the planning of a new framework of topographical vertices around the areas of the main temples of Tharros, for obtaining the absolute geographic positioning of all new surveying activities. This operation was carried on through differential GPS and total station (Boschi & Silani, 2014, pp. 43-45).
In a second stage, the "Monumental Temple" complex (Temple Ramp, Platform, Quadrilateral Building, the bagnarola Cistern and all the space delimitated by the temenos) was detected for the first time with laser scanning technology.
The application of laser scanning within a topographical survey allows the measurement of millions of points in an all-around view across space and the generation of a point cloud of surveyed objects (Remondino & Campana, 2014;Giorgi, 2009, pp. 253-256;Silani, 2017, pp. 29-36). In the field, several scans are collected from different points to cover the whole planimetric and architectural development of the structures.
In the "Monumental Temple" topographical survey, the complete coverage of monument surfaces was guaranteed by the acquisition of 73 scans with a Faro 3D Cam2 Laser Scanner (with a scan detail equal to 6 mm to 10 meters) equipped with a high-resolution ISTAR Fusion HDR spherical camera. Faro 3D Cam2 is a shift-phase based Laser Scanner that allows the recording of data with high detail, so it is particularly suitable for measurement of objects and surfaces at close range distances and for architectural survey. On the other hand, this laser is characterized by a lower range of acquisition if compared to other instruments, such as time-of-flight type laser scanners.
Subsequently, the raw data collected in the field were processed with dedicated software (ReCap by AutoDesk) and different scans were recorded and joined through a specific workflow: a first phase of prealignment consists in the identification of targets or homologous points between pairs of scans or pairs of groups of scans (cloud to cloud alignment); in a second phase, the software, through application of ICP algorithm (Iterative Closest Point), compares the scans, reduces the differences between homologous points and creates constraints between single scans (Silani, 2017, pp. 29-36). The texturing of the points took place through the internal camera of the laser scanner or in association with the NcTech ISTAR spherical camera to obtain a better colour balance of the photographic sockets. By recording all scans previously processed, at the end of this post-processing workflow, a single cumulative, texturized and georeferenced point cloud of the whole "Monumental Temple" of Tharros was created.

Results and Discussion
Topographic mapping instruments and very high precision lasers are ensuring a detailed record with different levels of analysis (Fariselli, Boschi, Silani, & Marano, 2017, pp. 322-324). The topographical survey of the temple through the application of laser scanning technology enables an updated 2D documentation (plans -sections and cross-sectional views). In fact, the final point cloud (Fig. 6) represents the base product for extrapolating plans, sections and perspective drawings of the buildings, produced with Computer Aided Design software (CAD) through the elaboration of horizontal or vertical slices of the cloud. First results of this phase of work on the Tharros "Monumental Temple" or "Doric half-columns Temple" comprise updated plans of the structures (Fig. 7) and new perspective drawings of the whole sacred area (Fig. 8), according range of precision and accuracy -thanks to the use of Faro 3D Cam2 Laser Scannernever previously achieved in the topographical documentation of monumental buildings of Tharros. Considering the lack of similar archaeological and topographical documentation for the Tharros sacred spaces and sites, this methodological approach -applied for the first time to the "Monumental Temple" -is able to support the analysis of the wall stratigraphies and to achieve complete knowledge of the monument: its original planning, its different building phases and its monumental development between the Punic and Late-Roman periods as well as the ritual use of the spaces.
Meanwhile, in 2018 we worked in the temple beside the "Doric half-columns Temple", the so-called "Court Temple of Semitic type" using the same methodological approach. In 2019 the "Sacra Tharrhica Project" will carry on with the topographical survey of two more sacred areas, "Temple K" and the so-called "Demeter Temple", but using a time-of-flight laser scanner, in order to acquire wider range measurements, useful for the survey and for the reconstruction of the urban and environmental context of the temples, but also to compare different technologies and approaches to the field-work.
The topographical survey of the temples by the application of laser scanning technology will also enable the creation of 3D models. The "Monumental Temple's" point cloud will be processed in order to obtain 3D models of the buildings: each point will be interpolated to create surfaces (mesh) and volumes that will be texturized with spherical images collected during the survey on the field, using laser integrated camera or external High Definition cameras, made coaxial to the laser scanner instrumental centre. Apart from historical and archaeological study, the resulting model aims to be useful for the conservation and modern Unauthenticated Download Date | 2/4/20 9:47 PM management of the archaeological area, giving a basis for the analysis of the archaeological monument's structural aspect and its health in order to facilitate restoration and securing projects, as well as to foster the public fruition of the whole archaeological area of Tharros.