Articles by Maurizio Forte

In this paper the authors present the approach in the study and reconstruction of archaeological landscapes that has characterized their work carried out at CINECA Supercomputing Center of Bologna, in the Visualization lab (VISIT lab), and in the Institute of Technologies Applied to Cultural Heritage of CNR (CNR-ITABC). The digital pipeline defined in these years of work has lead to the reconstruction of actual landscape (and archaeological landscape is part of our contemporaneity), past landscape, and ecosystems. The presented methodological model is a relational model that uses both bottom-up (data processing from fieldwork with integrated technologies) and top-down (landscape reconstruction through conceptual models, comparative analysis and mental maps) approaches. Landscape virtual museums can be built as ecosystems made of models and dynamic behaviors, where data can be read in a transparent way because of their association with a visible ontology. The proposed digital protocol is defined by procedures, tools (hardware and software), exchangeable data/formats and technologies such as GIS, OpenGL graphic libraries, terrain generators, Open Source software. It integrates 2D spaces and 3D, raster and vector, grid and polygonal models, text and multimedia, with the goal of offering a real time access to cultural and environmental information through off-line and on-line Virtual Reality applications and, in the future, virtual communities that could share experiences in and of the same spatial 3D landscape-mindscape.

The revolution of digital technologies in the past has focused attention mainly on the technical power and not on the semantic level of informative and communicational aspects. In the field of virtual heritage the risk was/is to enhance the amazing esthetic features despite the informative/narrative feedback and cognition within the virtual worlds. How much information can I get from a virtual system? How does it communicate? How can we process this kind of interactive information? The importance of the virtual reality systems in the applications of cultural heritage should be oriented towards the capacity to change ways and approaches to learning. The Virtual communicates, the user learns and creates new information. Typically we define as linear learning, tools and actions, such as books, audio guides, catalogues and so on (in this case the communication is a linear sequence), and reticular learning VR systems where the user is immersed within reticules of information and visual data. In this paper we try to analyse the relations between virtual reality, cultural heritage and cybernetics according to an ecological approach.

What is Virtual Archaeology (from now on abbreviated as VA) really? And what is virtual? In a period of great technological-digital evolution in all scientific fields, it is even more important to try to decipher, monitor and critically describe the state of the art, with particular attention to those interdisciplinary areas which will represent the avant-garde of future research. The great communicative impact that archaeology offers in itself is greatly enhanced by the possible digital interfaces and by the comprehensibility that these provide for much more than the scientific community. Therefore, considering what has been noted in this overview and what will be discussed below, VA can be defined as digital reconstructive archaeology, computational epistemology applied to the reconstruction of three dimensional archaeological ecosystems, therefore, cognitive ecology. The epistemological aspect is essential in the assessment of computational processes and therefore, in archaeological activity. To the out-going elaboration one must increase the cognitive significance of the in-going data (“augmented” reality). The context is cognitively greater than the sum of its components and we must identify the “environment” of the VA in a structuralist sense. In the assessment of the application of VA therefore, an epistemological measurement is essential; if, in fact, we try to “measure” the cognitive quality of models there is a risk of completely destructuring the information in respect to the context. Moreover it is evident that virtual space, in the archaeological dimension, must be contextualised and hierarchically restructured in order to allow for the identification of the logical units of information in the geometry of the models; theoretically one should “undo” and “redo” the context to completely verify the geometric and functional system. Key words might be 3D, interaction, virtual models, and other variables described in the text.

This paper illustrates preliminary results of the research project “An inventory of the Terramare in the central Po plain: physiographic context, stratigraphic and structural characteristics, state of preservation”, part of the Cultural Heritage Special Project, promoted by Italian National Research Council. The project involves GIS and remote sensing applications in order to integrate different 2D-3D georeferenced data (sites, excavations, surveys, landscape and territorial data) such as: a) raster data (aerial photographs of different periods starting from 1950, regional cartography, DEM); b) vector data (cartography, thematic layers, archaeological sites, etc.); c) a DEM created by cartographic contour lines and using a total laser station on the ground; d) alphanumeric data (excavation databases, territorial databases). The methodological approach has been to represent and analyse archaeological data from micro-scale (intra-site) to macro-scale (inter-sites), in particular exploring the perspectives of 3D GIS visualisations. Attention was therefore concentrated on the topographical reconstruction of microrelief in relation with the aerial photos (of different periods) used as textures, geomorphological features and archaeological data. We can define this kind of processing as a visualisation of an invisible landscape, as much more information can be retrieved from the terrain than using traditional techniques (aerial photo-interpretation, survey, etc.); in many cases this is very useful in order to help plan an excavation. Regarding the acquisition and processing of multi-temporal, multi-layer and multi-dimensional data, this research deals with a large-scale detailed study of the data collected by topography, but enhanced by surveys and acquisition of data on the ground. In fact one of the main tasks of our project is the creation of detailed models on the basis of the microrelief.

The main target of the Sistan Project is the reconstruction of the prehistoric archaeological landscape, beginning from multispectral satellite data. In order to draw a new map (historical, cartographic and geological) of Southern Sistan, a TM image of Landsat 5 satellite was used, with a resolution of 28.5 mt per pixel, including 7 spectral bands. By comparing geological features with the position of archaeological sites in the prehistoric age, and processing this digital data, new information have been obtained and hypothesis proposed for the ancient population of the region. In particular, DTM (Digital Terrain Model) reconstruction, multispectral classification (raster data) and vector integration of data (archaeological sites, terraces, geomorphological features, contour levels), have allowed us to visualise a complex and dynamic model in 3 dimensions. For this aim virtual reality techniques (not immersive) have been used: on a workstation, the user can explore in 3D the landscape model in an interactive way, navigating through the digital data and choosing different perspectives and points of view. Moreover, it was also possible to process at the same time multidimensional information, such as the altimetrical model, unsupervised classification, natural spectral color, different spectral bands, vector data and so on.

In every region of the world there are some areas that assume an important role for cultural change and development of the neighbouring regions. This was the case of the Belice Valley in Sicily: its primary role in cultural change was the product of its long running in North-East/South-West direction that cuts almost all of Sicily from North to South, connecting the Tirrenian Sea with the African Sea. This preliminary study concerns the project “The Belice Valley: early cultural development in the Mediterranean area”, carried out in order to analyse the archaeological landscape on the basis of the socio-economic activities in pre-defined archaic societies. In order to process this complex information, we have started to undertake GIS and remote sensing applications reconstructing 3D models of the valley from macro-scale (territory) to micro-scale (sites). Finally, with virtual interactive navigation through the archaeological landscapes, we have created cognitive models of archaeological information that may hopefully also be useful for planning new archaeological parks.

The ARCTOS project (Visualization and Virtual Reality methodologies for a cognitive system on a archaeological Sicilian pattern) has been carried out by CINECA (Interuniversity Consortium for Supercomputing Applications) and the Scuola Normale Superiore (Pisa, Laboratory of Ancient Topography) with the support of IBM SEMEA, in order to study the archaeological site of Rocca di Entella (Palermo). This is an important archaeological multistratified site dating back to the Neolithic through to the medieval period; in particular, 13 archaeological areas have been investigated in the last years. Rocca di Entella can be described as a separate geomorphological space 60 ha wide; for every chronological phase the structures discovered show different features, such as buildings, materials, functions and uses. To analyse these complex layers of information, data was processed in 2D and 3D format so as to visualize the scientific content; in particular, it was important to allow the users to move in real time into virtual spaces, such as archaeological landscapes. We think that interactive 3D perception is fundamental for our cognitive system as it allows us to understand all the features of the archaeological landscape and the inter- and intra-site relationships.

The recording of archaeological data during excavation and their description is a fundamental question for visualization and processing. Typically, this acquisition of data includes conventional 2D drawings, photos, graphic reproductions and videos. Further, we must also consider that for reconstructing the archaeological context (monuments, buildings, stratigraphic layers) it is very important to describe the 3rd dimension. The processing and visualization of 3D information may be considered as a virtual research lab, in which it is possible to recreate all the phases of excavation. In order to obtain these results, we have implemented the Shape from Motion Project, for modelling and 3D reconstruction of digitized and calibrated analogies video data. The project has been undertaken as a scientific partnership between CINECA, CALTECH (California lnstitute of Technology, USA) and AIACE (International Association of Computing in Archaeology

The research activity developed at the Scientific Visualization Laboratory of CINECA (Interuniversity Computing Center, Bologna, Italy), concerning the virtual navigation of archaeological landscapes, has produced important results in archaeological data visualization. We have implemented the application of virtual reality in the archaeological field relating to archaeological landscape exploration, archaeological site visualization, and ancient topography reconstruction. The virtual navigation is not full immersion but uses the 3D Crystal Eyes System, an ultrasound tracking system with six degrees of freedom. The system runs on an Indigo SG Extreme workstation. Some of the data was processed prior to visualization using GRASS GIS with a 3D viewer module

S. Rosa terramara, which measures 7 hectares, is a Middle and Recent Bronze age site, excavated since 1984. Cooperation between archaeologists and geologists has made it possible to experiment with the comparative analysis of computer image processing of the aerial photos, integrated with the detailed study of a DTM (Digital Terrain Model), in particular in relation to the geopedological and geoarchaeological interpretation of the site. The integration of two kinds of data, aerial photographs and a DTM, has been complemented by the texture mapping of the aerial photo overlaid on the corresponding 3D model. Significant ranges in the pixel distribution in the digital aerial image identified four main areas; any area presents particular digital features. For example, the digital features of the small village are very different from the characteristics of the large and more recent village. The digital classification of these areas identified the following: area 1, alluvial sediment (posthumous) which hides part of the earthwork; area 2, the nucleus of the small village; area 3, the diking of the big village; area 4, a Roman villa (another posthumous event). The final interpretation, after processing, distinctly shows the formation of natural (vertisoils) and artificial deposits (earthworks). In particular in the north-western area of the aerial photograph the interruption of the diking means that in that point the structures are buried because of a flood. Moreover, it results that the two villages are separated by a large ditch. On the basis of these results it has been possible to reconstruct the evolution of the site and of the environment in different periods: 1) the site before the Bronze age; 2) the terramara in the Middle Bronze age; 3) the terramara in the Recent Bronze age; 4) the site in Roman age; 5) the site in Medieval age. The computer processing, integrated with the aerial photo-interpretation, shows an important series of data not obtainable through traditional techniques. The construction of the DTM, the texture mapping and the digital image processing have clearly enhanced the shape of the structures of the terramara as well as the stratigraphical excavations. This also resolves the problems which emerged in the aerial photo interpretation. In particular, the interruption of the earthwork of the big village in the northern area seems connected with the burial of part of the anthropic structures, after the abandonment of the terramara. In conclusion, the computer image processing, together with the DTM and the texture mapping of the site, is an exportable tool, useful for an evaluation of the state of preservation of the Bronze age deposits in the Po valley. These results were obtained without excavation, using only simple stratigraphical surveys on the ground.

Ceramigraph is an electronic and mechanical system designed to draw pottery through automatic processing and therefore excluding the problems of manual drawing. The system, particularly suitable for large quantities of pieces, is composed of a high precision 3D pantograph, connected with a Personal Computer and a digital tablet. The main features of the drawings are the following: digital; vectorial; processed by software; classifiable (on the basis, for example, of the Freeman code); printable on normal or glossy paper at any scale; recordable on databases, CD rom, syquest, floppy disks, and so on (the size of vector files is very small; for example on a 1.44 floppy disk, 100 drawings can be recorded). The classification and the representation of the graphical information processed in this way are fundamental for the typological and typometric interpretations.

Computer simulation of natural phenomena is one of the most attractive and modern subjects for image synthesis. Simulation is the result of many processes, computed with mathematical models, which can be visually represented on a graphic screen. The synthetic image of the model generated can then be compared with other available information, and thus the image becomes an instrument for furthering knowledge. Two problems exist in the visual simulation of natural environments and 3D navigation. The first one is the construction of a reliable and detailed Digital Elevation Model (DEM or Digital Terrain Model, DTM); the second one, closely tied to ambient simulation, is terrain rendering, that is, the reproduction of the colour vision in the observer. DTM’s can be generated from isoliner or regular point data, using classical models (linear interpolation and Kriging) or fractal models (Brownian interpolation). In this example the aim is to create a landscape model (including archaeological sites) using a DTM and satellite or aerial images; these applications involve the following steps: acquisition of isolines from cartographic maps at any reasonable scale; DTM generation; digital image classification to determinate the pixel distribution map for the DTM; image synchronization (digital aerial photographs or satellite images synchronized with the DTM); texture mapping and generation of 3D images. In practical terms, the texture mapping involves the overlaying of the original image point by point on the DTM: the result is a realistic and significant landscape 3D image. This kind of simulation is especially useful to enhance the geomorphological characteristics of the landscape in connection with its evolution and the ancient settlement. Inside the image the researcher can move, navigate and explore, as in the real world. The example described concerns the Etruscan town of Marzabotto in the Reno Valley (Bologna). A realistic and representative 3D image was achieved which includes important topographical and geomorphological information about the archaeological site and the Reno Valley, the natural resources, and the correlation between the Reno river and the Etruscan town. A digital vertical aerial photography was overlayed on the DTM of this area, generated from cartographic isolines and contour lines. The processing consists of different steps: the first one is the digitisation of the aerial photograph (scale 1:30.000), in order to create a numeric input for part of the Valley of Reno, including the archaeological area and the DEM model with a topographical sample. The aerial photograph was digitised using a CCD camera and converted into a numeric format in raster file (RGB 24 bit plane, resolution 595 x 394 pixels). It was aligned with the DEM model using a regular grid with a resolution similar to the one of the digital image. Special hardware (SGI workstation) was used for the final rendering; the polygon rendering did not follow the usual texture mapping technique, but instead a geometric texturing was produced (one polygon per pixel). This technique allows a lower sampling noise (antialiasing) without heavy software interpolation. In this way the only problem is related to the dependence on the graphic library GL which is implemented either on a Silicon Graphics or RISC 6000 IBM platform.

The digital image processing technique is a complex computational tool which allows the powerful extraction of relevant information from digital data. A research project has been developed at CINECA (InterUniversity Supercomputing Center, Bologna) in cooperation with the University of Rome “La Sapienza”, in order to produce specific image processing tools for archaeological applications. The application fields are: digital analysis of aerial photographs; remote sensing; automatic classifications; automatic drawing; Digital Elevation Models (DEM); texture mapping; 3D landscape navigation.