Graphic: TecnoArt; © A.R.S 2015.

The Royal Palace is a significant architectural palimpsest, encompassing remains from across the entire history of Palermo, from the Punic-Hellenistic and Roman eras to the Norman period, and from early modernity to today. The importance of this site was made clear between 1984 and 1986, when some sections of the Punic and Hellenistic city walls were discovered below the Palace, together with one of the most ancient city gates of Pànormos, as Palermo was then known. More than 2500 years of history have produced a site of incredible archaeological complexity, the constructional stratigraphy of which is extremely difficult to investigate.12 According to late 11^th-century Latin sources, the Normans founded a fortress soon after they conquered Palermo in 1072. The reconfiguration of the building undertaken in the 16^th and 17^th centuries by the Spanish court and the addition of early modern structures reshaped the medieval castle into a modern palace (fig. 2). A number of medieval Latin and Arab texts and documents permit us to arrive at a hypothetical reconstruction of the Norman Palace as it appeared in the late 12^th century (fig. 3, fig. 4).13 The place where the Normans built the palace did not consist of a natural hill. The whole palace lies at an altitude eight meters higher than the Punic levels (fig. 5), a gap filled with stratifications belonging to pre-Norman phases of construction that were in need of better understanding.14 Importantly, the physical context that surrounds the famous Cappella Palatina – a wonderfully preserved cornerstone of medieval Mediterranean art – had never been properly investigated.15 The idea for a comprehensive project focused on the study of the Royal Palace was prompted by Maria Andaloro in 2009.16 The pioneering holistic approach17 aims to re-contextualize works of art within their original – and often lost – medieval spaces, a project that requires combining different disciplines in order to produce and convey knowledge. A multidisciplinary team from Tuscia University was in charge of the project, which I had the responsibility to coordinate. This challenging endeavor was performed in collaboration with Tecnoart, a company that specialized in innovative information technologies for the presentation and study of cultural heritage.

I wish here to highlight two aspects of the project. The first is related to the concept of epistemological objectivity and transparency. In 1933 Alfred Korzybski stated , “A map is not the territory it represents, but, if correct, it has a similar structure to the territory, which accounts for its usefulness.”18 Well aware that a model is only a way to simplify reality, and that objectivity is only a chimera – something to aim for, but impossible to achieve or encompass,19 as relativity, quantic physics, and Heisenberg’s uncertainty principle have demonstrated20 – and cognizant of Panofsky’s assumption, our archaeological approach sought to integrate historical data, materials, and knowledge deriving from scientific analyses – physical, chemical, geological, mineralogical, hyperspectral – with visual-aesthetical data. The digital surrogates produced through this process, although missing aura, physical substance, scale, life, context, and experience,21 are capable of incorporating material data and evidence into the visual model. More than a simple virtual replica or a digital twin, the surrogate thus becomes something else in comparison to the original starting point: it is identifiable as a new creation. The power of this sort of digital copy lies precisely in its ability to supersede the original object to convey more pieces of information and to do so as they are perceived, recorded, and interpreted. It thus opens avenues to scientific approaches, while also making processes, and uncertainties, trackable and transparent.

The second aspect to be considered is that by analyzing the workflows of different processes during the creation of the digital reconstructions, we could individuate two opposite vectors: one is progressive, as it starts from surviving archaeological evidence and other more readily available data, and reconstructs the lost, disappeared past; the other is regressive, as it starts from the current configuration of the space and architecture – i.e., the product of alterations, transformations, and stratifications – and excavates backward through it until a previous configuration comes to light. In both cases, it is essential to start from objective evidence. However, in the first case, our ‘time machine’, although returning back into the past (in a time before a given destruction occurred), will mainly move forward, in a constructive direction. In the second case, instead, the process starts from the present, returning back to the past through a destructuring process (in a time before a given new phase of construction and stratification happened). The Royal Palace case study began with a regressive approach: before modeling reconstructions, we performed a laser scan three-dimensional survey of the current configuration of the monumental complex. The utility of such a survey is obvious, for it permits us to extract any plan or cross-section (fig. 6, fig. 7).

But the 3D model alone does not represent the real strength of the project. As part of our collective research, we carried out numerous types of scientific analyses, including identification of mortars and building stones, chemical analyses of mosaic glass tesserae, georadar and thermographic imaging, hyperspectral photography, and mapping of the mosaic surfaces. Focused databases preserve all the outcomes, files, documents, and information derived from these analyses, as well as from bibliographic and archival research. The innovative aspect arises from the manner in which the 3D model serves as a virtual platform or container, making it possible to present the data in their precise spatial and topographic context (fig. 8).

Such innovative methodology offers the chance to study the Royal Palace in a new way. Applications of this advanced tool can help to clarify the intricate relationships among the construction phases of the building, the still uncertain relative chronologies, and the original configuration of the medieval space. The most important findings of this project were presented in June 2018 at an international conference which I organized together with Maria Andaloro, William Tronzo, and Jeremy Johns.22 One example will suffice: the resolution of a crucial issue related to the medieval configuration and function of the Cappella Palatina. Many scholars, starting from Ernst Kitzinger,23 based their interpretations of the arrangements of mosaics, internal distribution of spaces, and multiple functions of the Cappella Palatina upon the existence of a royal loggia, located on the north wall of the sanctuary, from which King Roger II would have followed ceremonies from a privileged point of view (fig. 9).24 The loggia that we see today is the result of mid-19^th-century alterations, but in 1992 Kitzinger published a precious drawing executed in 1790 by Leon Dufourny, which attests to the existence of the loggia before the 19^th century.25 Other scholars had questioned the existence of the balcony in the Middle Ages, on the basis of interpretations of some late 16^th and 17^th-century documents.26 Thanks to a deep analysis of the historical sources and the investigations performed on the architectural context around the chapel, it has been possible to verify that the first transformation of the openings occurred in 1585 when a new portico was built, the vaults of which obliterated the original windows on the north side of the chapel, thus modifying the loggia (fig. 10). The use of infrared imaging on this element has enabled the detection of the medieval openings (fig. 11), leaving room for interpretations (fig. 12) that may bring new life to Kitzinger’s compelling hypotheses.

Before concluding, I wish to present some drawbacks to the approach used in this project.

First: the amount of data produced is really high. The dot cloud alone comprises more than two billion points. The datasets are constituted by more than 400 entries, the photographer Gaetano Alfano took more than 2000 pictures, and the total amount of gigabytes produced is extraordinary. This forces us to confront issues of High versus Low resolution. A good compromise would consist in managing multi-resolutions, but the real issue is: to whom do we plan to address our digital model? While addressing these projects to the general public would be democratically important and efficient in promoting culture – and would allow us to opt for lower data resolution in the interest of broader divulgation – I am quite skeptical of the idea that this kind of endeavor could ever be designed for general public only, for our responsibility to convey knowledge would risk to be compromised by a lack of knowledge. In other words, the lower level of detail (resolution) appropriate for a general audience reduces the utility of the model as a tool for advanced interpretation. In order to visualize complexity, we need first of all to understand it; only once we understand it can we have the chance to transform it into ‘simplexity’.27 Therefore, the first aim should be that of creating a powerful tool to investigate and interpret reality, whether current, past or future. But another critical point emerges, concerning resources, funding, and clients. It is clear that to produce an accurate model, we need more resources and time. According to our experience, the government can be an appropriate sponsor for these kinds of investments in cultural heritage, but projects work better if they are not constrained by political agendas, and, of course, if a research center, being it public or private, is the one responsible for project administration, management, and coordination. In 2016, the contents and technologies of the Royal Palace project were delivered to the Sicilian Regional Assembly, which is responsible for maintenance and public dissemination. Today the model is not available online, for the municipality does not have the capability (and the will?) to manage the firmware updates, software migrations, and other steps necessary to maintain the model and the databases online, and it is even difficult for we, the project’s creators, to use the model. So, the risk is that, in the near future, all of this new digital cultural heritage concerning Sicilian patrimony will be lost.

For my conclusion, I kept some positive points:

First, the importance of designing at a high-definition level is also an answer to another fundamental issue, that of documentation and preservation of cultural heritage in advance of damage or loss. For instance, thanks to the CyArk foundation28 the temple of Bel in Palmyra, Syria, unfortunately lost in recent years, has been virtually reconstructed from tourists’ pictures.29 Unfortunately, once we zoom into the 3D model, the image reminds us that we have lost the primary source of knowledge and every detail of it (fig. 13). Imagine if we had had the chance not only to take pictures but also to perform a HD digital model of this UNESCO world heritage site. Second, we assumed that a 3D model can be considered as a photographic documentation. Unlike, however, an analog snapshot or a printed book, a digital model should be considered not as frozen and static but as alive and dynamic, capable not only to take us traveling into the past but also to follow and document ongoing events, being something incrementable and updateable over the years. In this perspective, digital surrogates should be embraced as one of the most powerful tools for transmitting to the future the present knowledge of the past.

13 Figure 13.

https://collections.arck-project.org/view/ARCK3D0000000253; (©) The Arck Project.