About the SCORPiò-NIDI PROJECT ^†

Abstract

This paper presents a summary of the activities carried out in relation to the shared objectives of the SCORPiò-NIDI project, an interdisciplinary research initiative aimed at investigating ballistic traces preserved along the northern fortification of Pompeii, produced by Roman siege engines during the siege of 89 BC. The study integrates digital surveying, computational modeling, experimental archaeology, and visualization techniques to document, analyze, and interpret specific types of anthropic damage caused by large stone projectiles and metal-tipped darts. High-resolution 3D acquisitions and reverse engineering processes guided the formulation of reconstructive hypotheses concerning projectile trajectories, impact velocities, and energy transfer mechanisms, supporting the determination of dimensional modules on the basis of which ancient treatises describe the proportional design of dart-throwing and stone-throwing machines in siege conditions. Mechanical simulations and comparative analysis provided quantitative validation of the virtual demonstrators prototyped and/or reconstructed using techniques and materials compatible with the pre-Christian period. The project further developed interactive digital models, animations, and visualization tools to support knowledge dissemination and public engagement. By combining archaeological data, engineering analysis, and human–computer interaction strategies, this research demonstrates the potential of digital technologies to enhance the study, interpretation, and communication of cultural heritage.

1. Introduction

The SCORPiò-NIDI project aims to provide a significant contribution to advanced research by demonstrating that effective conservation of cultural heritage (CH) can be grounded in the ability to deepen the scientific understanding of inherited assets. The dissemination of results, when adapted to contemporary needs and expectations, offers the opportunity to stimulate cultural tourism programs and socio-economic investment. The case under investigation presents features of exceptional significance. Pompeii is renowned for preserving every aspect of daily life at the precise moment of 79 AD, when it was buried by the first of a series of catastrophic eruptions and earthquakes [1].

Just over a century has passed since the excavations in the northern section of the fortification were completed. Once brought back to light, the wall revealed clearly visible impact marks generated by the violent collision of large stone balls, many of which were found in situ and accumulated in large quantities within the Park’s storage areas [2,3]. In addition to the clear evidence of the damage inflicted by the ballistae of Lucius Cornelius Sulla during the conquest of the city in 89 BC, numerous ballistic impacts produced by other types of projectiles are also preserved. Indentations of varying depth and geometric form were caused not only by ballistae (stone-throwing machines), but also by Roman catapults (dart-throwing machines), lethal slings, and arrows shot by archers [4].

The study by Mike Burns, conducted between 2003 and 2004 within the Anglo-American Pompeii Project (AAPP), analyzes different types of Roman artillery damage [5]. However, the manual and analog approaches underlying this research present limitations in terms of accuracy, accessibility, and reproducibility of the documented evidence.

By contrast, the implementation of digital technologies currently enables precise and accurate reconstructions of reality, providing research with documentation that proves valuable over time for further studies and socio-economic programs. Photogrammetry, 3D scanning, geographic information systems, and advanced data analysis tools evidence that natural disasters and human actions might otherwise erase permanently. At the same time, digital procedures introduce computational analytical methodologies capable of guiding developments that—within an interdisciplinary framework—can reveal previously unrecognized aspects.

The verification of original and innovative hypotheses is supported by casts of the internal surfaces of selected impact traces, chosen as representative of the analyses conducted. Positive and negative models provide a means to access the proportional relationships of the components of torsion-powered machines, which in antiquity stored energy by twisting bundles of elastic fibers using paired arms released on command. Their functioning is now relatively well understood after approximately two centuries of research. Several reconstructions have been calibrated on the basis of measurements derived from archaeological finds and interpreted according to classical criteria. The uniqueness of the archaeological evidence analyzed in this study makes it possible to reverse the traditional deductive reasoning process—the investigation proceeds from the recorded effects back to their causes. The measurements required to define the dimensional modules used to proportion the machines are derived from the morphometric characteristics of cavities acquired through digital methods. Reverse engineering processes enable the verification of terminal ballistic parameters, from which it is possible to infer the power of the artillery and the weight/mass of the projectiles.

Advancing this knowledge in order to protect and enhance the cultural model at the root of Roman civilization—shared by Western societies—supports the intention to:

(i)

Document archaeological evidence unequivocally attributable to elastic torsion-powered machines, made possible by the exceptional preservation of ancient Pompeii;

(ii)

Verify the functioning of ballistae and scorpiones, optimized by the Romans on the basis of principles developed by Greek scientists to increase lethality over greater distances;

(iii)

Reinterpret the history of sieges through experimentally verified data and calculations, assessing the compatibility of proposed hypotheses.

The research group possesses the expertise required to address the multiple technical and engineering dimensions of the problem and to provide accurate and precise answers to the research questions. The conceptual and methodological potential offered by digital language extends well beyond the concrete objectives outlined above.

The method, developed in an associative form, focuses on two main outputs: the reconstruction of dart-throwing and stone-throwing machines calibrated on the observed effects, and the development of a technical-scientific framework capable of overcoming misunderstandings and approximate reconstructions, thereby disseminating Roman science and culture in accordance with contemporary needs and expectations.

In this context, “certified” digital models function not only as tools for documentation and validation, but also as environments for conceptual re-foundation, within which an information space can be designed to support programs extending beyond purely scientific purposes.

A future and broader integration among forms of collaboration would strengthen the value of the efforts undertaken. It is hoped that the results will contribute to the academic debate on the subject and, more generally, to the definition of a methodological framework suitable for redefining paradigms introduced by digital language across the macro-sectors identified by the European Research Council (ERC). At present, approaches integrating knowledge and methodologies from different fields remain largely confined to the technical-scientific skills required for acquiring morphometric data, through which classical treatises can be reinterpreted to produce 2D–3D design outputs. The production of real and virtual prototypes, defined in every morphological, structural, and functional detail, supports visual, tactile, and experimental experiences aimed at establishing a pilot line of “certified” demonstrators for scenarios grounded in scientific knowledge and intended for museum exhibitions—on-site, off-site, and online. To this end, the design of an information space in which to organize the “cathedral” of current and future contributions is considered essential.

2. Surveying and Modeling: Conceptual and Methodological Challenges

2.1. Operational Research Field (SH5_12)

Among the objectives of frontier research is the possibility of providing culturally meaningful digital twins. The combined use of modeling techniques based on image- and range-based 3D acquisition enables the construction of a virtual environment in which acquired data can be organized [6].

In overcoming disciplinary barriers, surveying—once considered preliminary to any critical analysis—now contributes to defining a cyclic and interactive process within a virtual space of conceptual re-foundation. In the most complete and interesting cases, the categories of “Representation” are interrogated and expanded in order to manage, within the digital simulacrum, a flexible and implementable ecosystem of information and models. By operating at different levels of iconicity [7], the design of an information space allows each discipline to contribute from its specific domain while maintaining due attention to the broader framework of the issues addressed.

Within this perspective, the experimental activity and the historical-military investigation conducted on the northern stretch of the fortification of ancient Pompeii aim to promote further research into ancient science applied to the technology of elastic-torsion artillery, whose historical development contributed to shaping a cultural model that represents a shared root of many Western countries. The ultimate goal of the research is to stimulate programs for the protection and enhancement of cultural heritage grounded in the scientific understanding of new and innovative aspects, even within a site as extensively studied as Pompeii.

At the origin of the workflow lies the non-contact survey of ballistic impacts—archaeological evidence that can be considered “relics,” delicate and fragile—identified along the stretch between the Vesuvio and the Ercolano Gates of the city walls, preserved beneath volcanic deposits for nearly two millennia.

Preliminary to reality-based data acquisition is the collection of historical, architectural, and military information. Fundamental principles of fortification were necessary for identifying the impacts selected as representative of the analyses. Field observation carried out by researchers and professionals trained in architectural and environmental surveying constitutes a disciplinary competence requiring knowledge, intentionality, rationality, and awareness. It is, in fact, a systematic and planned procedure through which the complexity of physical reality is translated into selected datasets—extracted and abstracted—in order to be classified into configurations that can be manipulated for analytical purposes. The objective is mediated by critical judgment: “De-signare (to designate)/Di-segnare (to draw),” as expressed in a long-standing disciplinary motto. Reducing arbitrariness and enabling objective verification of data—on which scientific work progresses—thus represents a primary necessity at every stage of documentation, critical analysis, and programmatic projection.

2.2. Tools, Methods, and Materials

In light of the main principles of fortification, field surveys were conducted on site. The causes revealed by large-diameter impacts are unequivocal: these are imprints left by stone balls exceeding twenty centimeters in diameter, violently projected against the wall. Their purpose was not to breach walls of considerable thickness, but rather they represent missed shots that today provide technically valuable information as evidence of the evolution of elastic-torsion artillery. Less evident, yet more intriguing, are the medium and small anthropogenic indentations, some measuring only a few tens of millimeters. The surface outlines on the stone blocks, their varying depths, and the direction of impact are elements that once again demonstrate the use of different types of artillery, employed in alternating phases of siege and for distinct offensive and defensive purposes. Damage caused by metal-tipped projectiles, although mentioned in the literature, remains among the least studied. The SCORPiò-NIDI project instead focuses on damage attributable to typological families of Roman dart-throwing catapults, renamed “scorpiones” by legionaries due to their resemblance—not only formal—to venomous arthropods of the arachnid class.

The use of terrestrial laser scanning (TLS), employed to document the investigated section with precision and accuracy, required careful planning of field operations. Geomatic expertise was necessary both to prevent acquisition errors and to facilitate the subsequent processing and alignment of scans into a unified model. A range of integrated tools and methods proved suitable for addressing the challenges posed by surveying the internal surfaces of depressions characterized by roughness and fragility due to the nature of the stone and its degradation, both natural and anthropogenic. These challenges became particularly significant in the case of small indentations, which are difficult to investigate using traditional techniques [8].

For this purpose, Structure-from-Motion techniques were effectively employed alongside structured-light sensors. The analytical work derived from the photogrammetric restitution of the cavities (see Rossi-Bertacchi contribution in the proceedings) enabled the extraction of morphometric data essential for calculating the volume of pulverized material (negative mold) and the volume—sometimes discretized into significant components—of the impacting objects (positive casts), reconstructed through automated procedures and data acquired from archives and museums of Roman antiquities.

Depth, diameter, and displacement constitute key parameters required to solve the calibration formulas transmitted by Hellenistic Greek and Roman treatise writers. Vitruvius describes in detail the criteria and principles linking the dimensional module—on which each component of the machine is proportioned—to the standardization of projectile weights and sizes, established in antiquity to predict weapon power and, consequently, artillery lethality at predetermined distances. On the basis of the dimensional modules derived from the analysis of recorded damage, the morphology of artillery devices was proportioned and subsequently rendered structurally and technically functional through information modeling (see Rossi-Formicola contribution in the proceedings). Virtual reconstructions of dart- and stone-throwing machines follow the principles described in detail by Philo of Byzantium (Belopoeica, 3rd century BC) and reported in subsequent Hellenistic treatises [6]. Rapid prototyping processes made it possible to test the technical solutions described by Philo and refined through the definition of construction details.

The same 3D casts from which morphometric data were derived—with appropriate adjustments—were also used to verify terminal ballistic parameters, which can be accessed and inductively tested through classical physics [9]. In parallel, reverse engineering processes verify the mechanical compatibility of impacts produced by spherical stone projectiles and metal-tipped darts. The model includes a subroutine implementing numerical damage modeling conceived as the interaction between the projectile and the mechanical behavior of the wall material.

The estimated initial velocity enables the calculation of firing distances—key parameters used in reconstructing siege scenarios. To this end, a pilot line of “certified” demonstrators contributes to exhibition setups—on-site, off-site, and online.

Digital infrastructures, in addition to supporting interdisciplinary collaboration, can evolve into structured environments that leave little room for improvisation, as they ensure explicit connections between raw survey data, processed models, accurate replicas, mechanical outputs, certified reconstructions, fabrication models, and physical prototypes.

2.3. Objectives, Activities, and Results

Certified demonstrators—as they are derived from the analysis of objective and physically verified effects—emphasize the methodological importance of metrically reliable digital surveying. The systematic documentation of ballistic traces, acquired through non-invasive techniques and processed within a calibrated analytical workflow, establishes a solid empirical basis on which to develop specialized analyses. Within the scope of the SH5_12 sector, particular relevance is given to the communication of interpretative readings of treatises in which ancient authors describe mechanical devices and, at times, elaborate on their observable effects (Philo of Byzantium, Belopoeica). The approaches developed reflect typical investigations of 2D–3D graphic modeling. Comparisons among families of dart-throwing machines—referred to in military terminology as scorpiones—calibrated on recorded and calculated damage, and reconstructed according to classical principles to be prototyped and verified in every morphological, structural, and functional detail, are employed for visual and tactile experiences.

Within cyclic and interactive processes of an intrinsically interdisciplinary nature, the results obtained and organized aim to generate a hybrid environment capable of accessing knowledge in order to project scientific work “beyond” established meanings, preserve memory, and respond to present needs and expectations. A plurality of languages and techniques therefore contributes to the construction of cognitive spaces through which historical memory can be explored and reconstructed by means of individual disciplinary approaches. Within an information space that integrates these contributions, a central role is played by the Social Sciences and Humanities (SH), and specifically by the objectives of “Computational modelling and digitisation in the cultural sphere (SH5_12).” In this context, the reconstruction of solid and culturally meaningful evidence does not end with ensuring traceability, portability, interoperability, and multidisciplinary accessibility, but extends to the conceptualization of an information space in which models are progressively organized to provide visualization services for different categories of users.

3. From Projectile Imprints to the Design of Roman War Machines: A Multidisciplinary Study of the Siege of Pompeii

3.1. Operational Research Field (PE8_10)

Scholarly interest in the ancient city of Pompeii, which remained buried for centuries beneath the lava and ash produced by the eruption of Mount Vesuvius in AD 79, has traditionally focused on the city’s urban layout, its architecture, and the internal organization of public and private buildings. This series study has enabled the acquisition of valuable knowledge about the Roman world and the lives of its citizens during the historical period surrounding the birth of Jesus Christ—knowledge that would otherwise have remained hidden.

Furthermore, the reconstruction of fragments of everyday life in Pompeii through body casts has made it possible to investigate aspects of daily activities that would otherwise have been lost forever. These reconstructions have provided, and continue to provide, a unique contribution to our historical knowledge and to our ability to understand and interpret the dynamics of the Roman Republic and, later, the Roman Empire, offering insights that extend beyond the local context and can be generalized to a much broader framework.

However, the strong focus on these important aspects of the discovery of the archaeological site of Pompeii may have diverted attention from other elements that are not less significant. When attention is directed to the city walls of Pompeii, it becomes evident that they played a crucial role both in protecting the city and in shaping its urban development. On the one hand, they hindered easy conquest by external aggressors; on the other, they defined the boundaries of the urban perimeter, thereby influencing urban development and planning decisions.

Although specific details concerning the Pompeian walls are limited, evidence from other ancient cities indicates that such fortifications fulfilled multifunctional roles, including defensive and strategic–military functions. It is likely that this multifunctionality also applied to Pompeii, influencing the selection of construction materials and building techniques. In light of these considerations, it can be stated that the analysis of the walls of Pompeii is far from exhaustive, and that a detailed study of these structures—similar to what has occurred for other elements of the urban fabric—can make a significant contribution to reconstructing the historical evolution of the city and the events that characterized its life, particularly in relation to its defense.

Historical sources indicate that during the Roman siege of Pompeii led by Lucius Cornelius Sulla in 89 BC, the city walls were subjected to intense bombardment by Roman artillery, including ballistae and catapults. The siege was part of the Social War, a conflict between Rome and its Italic allies. The northern walls of Pompeii, facing a plain, were particularly vulnerable and were reinforced by the Pompeians with additional masonry and towers. Despite these measures, Roman artillery left numerous ballistic marks on the walls, providing modern scholars with valuable data for analysing the power and accuracy of Roman siege weapons [10]. Documentary sources report that the northern fortifications exhibit numerous cavities, interpreted as the result of repeated projectile impacts. These features testify to the remarkable power of Roman artillery, which pulverized masonry surfaces upon impact [11,12].

Further confirmation is provided by the work of Onorato [13], who unequivocally attributes these craters to the siege conducted by Sulla in 89 BC, during which ballistae (machines designed to launch spheroidal stone projectiles) and scorpions (machines for launching darts with metal tips) were employed. Recent research on projectile impacts and the marks they left on the city walls during this siege has highlighted the durability of Pompeii’s ancient fortifications and has contributed to improving our understanding of ancient warfare and structural resistance [10].

Three-dimensional digital modelling of crater morphology conducted by Bertacchi et al. [14] has provided important insights into the intended use of stone projectiles and metal-tipped darts. The analysis suggests that these weapons were designed both to compromise defensive structures and to neutralize defenders [15]. The diameters of the analysed ballista projectiles ranged from 10 to 23 cm [16]. A recent analysis by Rossi supports similar conclusions, proposing that the craters observed on the walls may represent missed shots, with intended targets consisting of mobile protective devices used by defenders. Rossi’s survey of the Pompeian fortifications, built of Nocera Tuff, recorded penetration depths of up to 120 mm. They also described the crater morphology as cylindrical–spherical, with an average diameter of 140 mm and an orthogonal impact trajectory [10].

The experimental analysis described here, together with the digitization of the observed and studied features, offers the possibility of a broader investigation into the siege of Pompeii, its dynamics, and the management of the battlefield by the Roman army. Such a study requires multidisciplinary expertise, enabling both the correct and comprehensive processing of the acquired data and their interpretation considering different aspects of interest and possible alternative explanations, without neglecting factors that may influence conclusions.

The study developed within the present research program is well suited to implementing the concepts described above through an innovative approach based on reverse engineering. This approach ranges from the application of fundamental principles of ballistic mechanics to the mechanics of materials and damage, ultimately enabling the reconstruction of the battlefield, the positioning of war machines, and the definition of a design methodology for such machines based on modern mechanical design concepts. This methodology also allows verification of the extent to which these modern principles may have been unconsciously followed in ancient designs.

Moreover, redesigning Roman war machines according to current mechanical design principles enables an evaluation of the parametric design approach described by Vitruvius, which appears to have guided the design of Roman war machines by taking projectile size as the starting parameter from which all other functional and structural dimensions were derived. In other words, the development of this reverse engineering approach contributes to deepening our understanding of design methods within the complex field of mechanical engineering.

3.2. Tools, Methods, and Materials

Within this methodological framework, photogrammetric surveys of the walls and the positions of projectile impact craters, together with the geometric and dimensional characterization of individual imprints, constitute the starting point of the analyses performed. These analyses first make it possible to distinguish two clearly different types of imprints attributable to two distinct projectiles: spheroidal stone projectiles and pointed metal projectiles. Based on this distinction, attention was then focused on reconstructing the geometric and dimensional characteristics of the projectiles.

The development of finite element models simulating the impact of these projectiles against the walls enabled the determination of impact parameters such as direction and velocity, and ultimately the kinetic energy of the impacting projectiles. The development of these simulations is particularly complex: on the one hand, they involve dynamic analyses requiring the use of explicit solvers suitable for modelling nonlinear system behaviour and short-duration events such as impacts, with careful finite element discretization; on the other hand, they can quickly lead to computationally demanding and impractical calculation times due to the need for a large number of nodes and elements and very small time steps.

An additional layer of complexity arises from the need to accurately model the material damage mechanics during impact. The defensive walls of Pompeii were constructed using a variety of materials, primarily local volcanic rocks. The main components included Grey Tuff or Fiano/Nocera Tuff, which are stiffer and more resistant than the more extensively studied Neapolitan Yellow Tuff (NYT) [17]. Nocera Tuff is a grey volcanic stone belonging to the Campanian Ignimbrite (CI) [18,19], a widespread pyroclastic deposit generated by a massive eruption of the Campi Flegrei volcanic system approximately 39,000 years ago [20,21]. This ignimbrite, known for its durability and resistance to weathering, represented an ideal choice for fortifications.

The walls were likely constructed using techniques similar to those observed in other contemporary Roman structures, involving a concrete core composed of lime mortar mixed with volcanic ash (pozzolana) and aggregates [21]. This combination produced a strong and durable material capable of withstanding seismic activity and long-term settlement. The use of local volcanic materials such as tuff and scoriae as aggregates would have further enhanced wall strength and durability. The presence of zeolites in some of these volcanic materials may have contributed to the long-term mechanical strength of the concrete through pozzolanic reactions [20]. In this context, the intrinsic variability of materials and construction techniques necessitates caution in generalizations and requires models capable of incorporating, at least in part, such heterogeneity.

That said, modelling the mechanical behavior of these materials is challenging, both because experimental data on the wall materials are unavailable, since the walls are protected cultural heritage and cannot be sampled or damaged and because the dynamic behavior of stone materials under impact loading is itself poorly documented in the literature. Consequently, the definition of constitutive and damage parameters often relies on indirect data, comparisons with analogous materials, and cross-validation between numerical results and geometric evidence observed in situ, with inevitable uncertainties. These uncertainties, however, can be reduced through a robust and iterative methodological strategy.

In the present research, these issues were addressed by referring to constitutive material laws available in the literature and damage criteria used for materials with similar characteristics, calibrating the model through a reverse analysis process based on experimental evidence. Once the impact parameters were determined, it was possible—by applying the laws of projectile motion and basic aerodynamic principles—to derive the launch parameters of the projectiles, summarized by the initial kinetic energy corresponding to the elastic energy that the machines had to provide to launch the projectiles.

Starting with this information and referring to the functional layouts of Roman war machines and their typical dimensions as documented in historical sources, it was possible to determine the main dimensions of the machines. Of particular interest is the elastic element of the machines, through which the elastic energy required for launching was stored; in that historical period, this element was constructed using organic materials such as animal tendons or women’s hair.

This constitutes another source of uncertainty, given the well-known variability of the mechanical properties of such materials and the current difficulty in obtaining experimental data. Nevertheless, in this case as well, critical analysis of the results and comparison with existing approaches in the literature made it possible to calibrate the model describing the elastic element’s behavior and to account for its nonlinearity, thereby completing the reverse engineering process developed for the design of ballistae and scorpions war machines that played a major role in the expansion of the Roman Empire and civilization.

3.3. Objectives, Activities, and Results

The methodology developed, capable of accounting for the various nonlinearities that make the problem particularly complex, enabled design reconstruction of these machines and lends itself well to generalization using different initial data, with the aim of extending knowledge and understanding in a field of historiography that remains only partially explored. As noted, the approach is not free from uncertainties, linked to the inherent variability of the data and the difficulty of conducting experimental tests to reduce such variability and perform statistical analyses. Nevertheless, the use of inverse analysis techniques, made possible by the reliability of surveys and input data, and comparison with these data confirm the validity of the proposed approach and its ability to produce results consistent with historical war machines, which themselves exhibited variable characteristics due to the variability of the materials used.

It is interesting comparing the result of the present work with those outlined at the origin of the project by Russo & Rossi [21], the authors derive an impact velocity of about 109 m/s by equating the kinetic energy of a 0.15 kg dart to the deformation work required to crush a calculated volume of stone, assuming a uniform breaking stress and full conversion of kinetic energy into crushing work. Their analytical model, based on data and reasoning derived from experimental procedures developed by Greek and Roman treatise authors, while examining the data and optimizing the calculations prior to the design, continues neglects aerodynamic drag and treats the masonry response as homogeneous compressive failure, which likely leads to an upper-bound estimate. In contrast, the model developed by Thakkar et al. and included in this issue (Thakkar, M.M., Ardeshiri Lordejani, A., and Guagliano, M. ‘Analytical Evaluation of Elastic Rope Materials and Aerodynamics of Roman Scorpio Catapults Based on Archeological Evidence’), a much lower calibrated impact velocity of approximately 6 m/s based on finite element simulations matched to the observed 30 mm penetration depth in Grey Campania tuff. By means of this model it is possible to assess an initial velocity around 60 m/s, that is consistent with the known performance of torsion artillery and with their own later launch-velocity estimates in the range of 50–70 m/s. The discrepancy between the results of the two models highlights how sensitive ballistic reconstructions are the assumptions about material strength, energy partitioning, and failure mechanisms. Overall, the analysis of the results suggests that a refinement of the present results could be achieved by integrating dynamic fracture mechanics, calibrated material data, and the computational fluid dynamics modelling.

It is hoped that the results achieved will serve as a stimulus for further investigations and will be accessible to a broader audience, contributing to the expansion and dissemination of knowledge about the many aspects of life in the Roman era and as written by the project coordinator, Adriana Rossi, inspiring positive changes.

4. Authoring and Delivering Digital Cultural Heritage: The SCORPiò-NIDI Experience

4.1. Operational Research Field (PE6_9)

Digital Humanities (DH) have emerged as a well-established interdisciplinary scientific domain, originating from the convergence between humanistic scholarship and information technologies (commonly referred to as Information Technology—IT). This field no longer represents a mere instrumental extension of traditional disciplines but rather constitutes an autonomous methodological paradigm that redefines the processes of knowledge production, interpretation, and dissemination [22,23]. At the core of DH lies the transformation of cultural objects into digital objects (i.e., processable by electronic computation), an operation that necessarily involves explicit interpretative choices. The modeling of texts, images, and cultural practices into digital artifacts enables the application of quantitative, algorithmic, and visual methods, while simultaneously making visible the limits, assumptions, and implicit hierarchies inherent in every act of digital representation. In this sense, DH do not simply “digitize” cultural heritage, but critically interrogate its modes of formalization and access.

Within the context of digital cultural heritage, interaction cannot be reduced to a purely instrumental function of information access; rather, it constitutes a complex device that activates cognitive, perceptual, and emotional processes in the relationship between user and cultural content. The recent literature highlights how design choices related to interfaces, navigation modes, and visualization strategies significantly affect the construction of historical knowledge, the perception of content authenticity, and levels of user engagement [24]. From this perspective, Human–Computer Interaction (HCI) plays a fundamental role in the study and understanding of digital cultural heritage, as every digital interface acts as an interpretative tool, performing selections and mediations that inevitably shape the understanding of cultural assets. A particularly relevant aspect concerns the gradual shift away from models of content consumption based on passive reception, toward interactive and participatory paradigms in which users assume an active role in constructing their own cognitive pathways. This approach has proven especially effective in educational and museum contexts [25], where interaction supports experiential learning processes and contributes to the understanding of complex phenomena, such as long-term historical processes, architectural stratifications, and technological dynamics of past cultures. The diffusion of immersive technologies, such as virtual reality, augmented reality, and mixed reality, has further expanded the application of HCI within digital cultural heritage [26]. These technologies enable the synergistic integration of spatial, temporal, and narrative dimensions, offering multisensory experiences capable of bringing users closer to reconstructed historical contexts and making perceptible phenomena that are otherwise difficult to communicate through traditional media. In such environments, interaction extends beyond observation, involving the body and perception, and fostering forms of cognition in which understanding emerges through action and exploration.

Another central issue concerns accessibility and inclusion, now essential themes in HCI design for cultural heritage. Adaptive interfaces, multimodality (visual, auditory, tactile), and experience personalization are increasingly adopted strategies to ensure access for users with diverse abilities, skills, and cultural backgrounds. In this sense, HCI contributes to the democratization of digital heritage by expanding the potential audience and reducing physical, cognitive, and social barriers. Based on these considerations, it becomes clear that the study of digital cultural heritage cannot be limited to the mere production of data or models, but must also encompass the ways in which such content is made intelligible and accessible. Digital Humanities and Human–Computer Interaction provide fundamental theoretical and methodological tools for transforming complex information into accessible resources that promote understanding, learning, and public engagement. In this context, interaction and visualization do not play a purely technical role but actively contribute to constructing the meaning of cultural content.

It is on these foundations that the SCORPiò-NIDI project is situated, applying these principles to a concrete case study by integrating archaeological research, digital modeling, and dissemination strategies. The project aims to demonstrate how the conscious use of digital technologies can bridge scientific analysis and communication to broader audiences, overcoming the separation between specialized research and public engagement. In this way, research results are not confined to academia but are transformed into accessible, interactive, and shareable knowledge experiences.

4.2. Tools, Methods, and Materials

The SCORPiò-NIDI project examines the scars left by projectiles on the northern walls of Pompeii, transforming what at first glance appears to be mere stone degradation into a valuable research resource. Through photogrammetry and digital reconstruction techniques (reverse engineering), these material traces are converted into highly accurate 3D models. This data enables computational simulations to reconstruct projectile trajectories, impact force, and the functioning of ancient Roman siege engines. Digital technologies thus become a laboratory for testing the reliability of historical sources and ancient texts, comparing real artifacts with prototypes and mathematical models.

Within the project, experts in digital information processing were responsible for implementing a collaborative platform based on open-source development tools [27], specifically designed for the creation, dissemination, and exploration of certified digital artifacts derived from experimental archaeology and engineering-based reconstructions. The development of this platform represents the final stage of the project’s pipeline, in which static and dynamic models of Roman war machines and architectural contexts are transformed into accessible digital resources. The platform supports scientific communication, education, and public engagement while preserving methodological transparency throughout the reconstruction process. Its primary objective was to provide a scalable solution, accessible via browsers and mobile devices, enabling users to interact with complex 3D artifacts without requiring dedicated software or specific technical expertise. The activities undertaken aimed to move beyond a purely documentary conception of digital restitution, instead focusing on the construction of experiential forms of engagement capable of making the principles, methods, and outcomes of experimental archaeology applied to Roman siege engines and ballistic evidence on the walls of Pompeii understandable to a broad audience.

The work initially focused on the production and processing of three-dimensional models intended for dissemination. The 3D models of the scorpion and the ballista were subjected to optimization, texturing, and animation processes, with particular attention to representing the functional phases of the machines—loading, tensioning, release, and projectile launch. Animation was conceived not as a mere visual effect, but as an interpretative tool aimed at making the mechanical and ballistic principles underlying Roman artillery comprehensible. The integration of animated models with the three-dimensional reconstruction of Pompeii’s city walls enabled the machines to be placed within a coherent spatial context, strengthening understanding of the relationship between weapons, firing trajectory, and ballistic scars observable on the masonry. In parallel, an intensive activity of image and immersive scene production was carried out using advanced visualization software. The resulting renderings were designed as visual communication tools capable of combining scientific rigor with narrative impact, alternating photorealistic representations with technical visualizations to highlight the geometric and constructive complexity of the models. These images contributed to building a coherent and recognizable visual identity for the project, supporting both public dissemination and documentation of the activities conducted.

4.3. Objectives, Activities, and Results

Building on the theoretical and methodological considerations outlined above, the SCORPiò-NIDI project aims to demonstrate how the conscious use of digital technologies can connect scientific analysis with communication to broader audiences, overcoming the divide between specialized research and public engagement. In this way, research outcomes are transformed into accessible, interactive, and shareable knowledge experiences.

A central result of the activities carried out is the production of audiovisual dissemination content. In particular, two videos were produced, one primarily two-dimensional and one three-dimensional, conceived as autonomous narrative artifacts capable of conveying the project’s objectives, methodology, and results without requiring specialized knowledge. Video production involved defining a narrative concept, selecting and editing 3D animations, renderings, and contextual imagery, integrating a voice-over generated through speech synthesis systems, and selecting a soundtrack consistent with the intended communicative tone. The goal was to convey the project’s complexity in an accessible, engaging, and scientifically accurate form, emphasizing the role of digital technologies as tools of cultural mediation.

In the final phase of the activities, the project website was developed as a unified access point to the digital content produced. The work included designing the information architecture, developing functional wireframes, customizing a content management system, and integrating textual and multimedia materials. The website was conceived as a space capable of collecting and organizing models, images, videos, and texts, offering a coherent overview of the project’s activities and results, and laying the groundwork for future developments of the planned digital fruition platform.

Overall, the work strengthened the overall strategy of SCORPiò-NIDI by consolidating the link between advanced scientific research and the dissemination of cultural heritage. Animated models, immersive scenes, audiovisual content, and web tools have transformed data and reconstructions into communicative experiences capable of engaging diverse audiences and supporting informed and conscious engagement with cultural heritage. The digital artifacts produced also constitute a solid and reusable foundation for further dissemination, public engagement, and valorization activities.

The achievement of the scientific and dissemination objectives of the SCORPiò-NIDI project was made possible by the close integration of expertise from different disciplinary fields. This synergy was not merely instrumental, but a structural element of the project’s methodological framework, enabling a truly interdisciplinary approach to the study of Roman siege reconstructions. Expertise in heritage surveying and representation played a key role in translating material evidence and numerical data into reliable and intelligible geometric models. Through photogrammetric surveys and high-precision 3D modeling, ballistic scars on the walls of Pompeii and siege engines were transformed into rigorous digital models integrating metric, morphological, and interpretative dimensions. This expertise ensured coherence between real data, digital reconstruction, and visual narrative, acting as a bridge between scientific analysis and communication. The contribution of mechanical engineering was central to the physical-mechanical interpretation of archaeological evidence. Through ballistic analyses, numerical modeling, and computational simulations, specialists reconstructed firing conditions, projectile trajectories, and impact energy, providing quantitative parameters essential for understanding the functioning of Roman siege engines and validating reconstructive hypotheses derived from historical sources and material remains. Finally, computer science enabled the valorization and dissemination of results through the design and implementation of a dedicated software platform for the fruition of digital artifacts. IT specialists developed web-based solutions for interactive 3D visualization, content authoring, and access to multimedia materials, ensuring usability, scalability, and accessibility. In this way, research outcomes were transformed into digital resources accessible to diverse audiences, without sacrificing methodological transparency.

5. Conclusions

A cultural practice grounded in the scientific evidence provided by accurate and precise models of surveyed casts (of certain origin and chronology, given the exceptional nature of the site under consideration) made it possible to derive studies and tests that are repeatable and falsifiable concerning the interactions between projectile and target at the moment of impact and in the instants immediately thereafter. The results scientifically confirm the parameters empirically outlined at the inception of the project [1,2], based on empirical calculations derived from the formulas developed by Hellenistic treatise writers to plan the lethality of sieges. The criterion relies on morphometric data derived from advanced acquisitions of the indentations, which make it possible to calculate the volume of matter disintegrated by compression, in the case of spherical stone projectiles, or by chipping and fragmentation in the case of metal dart tips, thus allowing the evaluation of the work performed and therefore the energy required to pulverise, in the case of spherical projectiles, the stone material, or to cause chipping once the density of the stone material is known.

The integration of digital technologies as the core of the description and transformation of processes along the production pipeline (see Figure 1) has enabled the management of the data generated. A holistic approach to the management of data produced along the cultural heritage (CH) pipeline has suggested corrective measures and methods to overcome certain critical issues in the visualisation of results, thereby favouring the use of partial results across different sectors. To date, outcomes limited to scientific exchange among experts have compensated for: (i) the lack of interoperability among data types produced for different purposes; (ii) difficulties in data retrievability; (iii) the possibility of adapting data to different visualisations and interfaces according to user profiles, objectives, and service typologies in which the data are employed; (iv) excessive specialisation and isolation within information silos (a management method in which an information system is unable to operate reciprocally with other systems that should be correlated).

From the perspective of information design, the conceived information space is based on concrete facts and calculations, constituting a scientific premise that ensures coherence between archaeological data and digital visualisations, within which the general model has allowed each contributor to intervene. The platform, currently conceived and organised exclusively for scientific consultation, has played a fundamental role through user-centred cultural heritage methodologies. In line with the guidelines established for the Cultural Heritage (CH) sector, the research programme intended for extension will generate a shared and interoperable network to plan and organise hypotheses aimed at making studied and digitised materials accessible, in order to transmit their social, cultural, economic, and tourism value beyond national borders. The work proposes an approach designed to broaden access to cultural heritage and to promote conscious interaction among member states. The ultimate aim of the promoted actions is directed toward the organisation of an “open data” system useful to policy makers for acquiring visual and structural information on the subject. The outcomes lend themselves to guiding the organisation of projects and programmes of interest to be included within Erasmus Plus initiatives as well as at the broader European level. The results achieved include the discovery of the use of the polybolos, an issue that deserves further investigation due to the uniqueness of the archaeological evidence constructed and identified. The “certified” outputs will make it possible to set up several museum spaces:

• “in situ”, by exhibiting, in front of the northern circuit of the Roman city, full-scale prototypes that clearly demonstrate the relationship between elastic weapons and the lethality of the damage produced;
• “on-site”, by setting up exhibition spaces featuring real and virtual models. To increase visitor engagement, experimentation with innovative materials is envisaged—materials that, within our project, are also useful for the production of artefacts—in order to ensure comparable performance while reducing costs in the reproduction of multiple copies;
• “off-site”, through virtual galleries of 3D models accessible via the internet, interactive, compatible with mobile devices, and designed to be simple and intuitive.

The demonstrators, which are the outcome of the production pipeline and currently accessible through a Digital Library (DL), together with the 3D models, will mediate access, across different phases (storing, harvesting, and retrieving), to different types of documentary media/data (images, videos, texts), following a systemic approach aimed at full knowledge integration. The adopted procedures are intended to enable the integration of data originating from investigations or from different types of documentation concerning the artefacts under study; the linking of information data to 3D models; the collection of additional information about the artefacts; the organisation of content within a hierarchical structure of forms; and the use of 3D models as the matrix of an information system, understood as a preferential access interface to various classes of data related to war machines.