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The recursive action of the survey has made it possible to advance the most intimate understanding of the construction methods of the artistic ceramics factory, built between 1954 and 1955 in Vietri sul Mare. The article presents and discusses the results of photogrammetry carried out using the SfM technique. The various fractures in the main front of the south façade, some of them at the height of the operator, led to the graphic description of the clay amphorae used to build the infill wall instead of perforated bricks. The process followed used two reality-based methods to transform the meshes into topologically modifiable models: 1) abstraction and extraction of the meshes converted into polyhedra 2) free-form geometries. The paper illustrates the process followed to obtain 3D configurations suitable to be processed for finite element analysis (FEA). The results will be used to help make the models derived from different other techniques such as laser scanning, informative.

Conservation of Cultural Heritage is a key topic and structural changes and damages can affect the structural behaviour of Cultural Heritage artefacts and buildings. Considering that the application of technologies can help in preserving, conserving and restoring ancient structures, it is mandatory to find the best pipeline to produce the correct analysis that can be provided with the use of Finite Element Analysis, a well-known technique used in modelling stress behaviour of objects and structures. The necessary workflow invests and involves design experts enabled to mathematically master the potential of models that pass from interpretation to design control. Following the principles of good experimental practice, the typical workflow involves the use of CAD 3D models made by Non-Uniform Rational B-splines (NURBS) surfaces, representing the ideal shape of the object to be simulated. Conversely, when applied to 3D models of Cultural Heritage, often altered by the time passed since their original creation, the representation with a schematic CAD model may introduce an excessive level of approximation leading to wrong simulation results. The focus of this work is to present a method based on retopology, hence on quadrangular element instead of triangles. Such process aims at generating the most accurate 3D representation of a real artefact from highly accurate 3D models derived from image-based and range—based techniques, maintaining the accuracy of the high—resolution polygonal models in the solid ones to be created for FEA. A proper pipeline can help to carry out the necessary interventions and perform virtual restoration prior to the physical one.

3D printing artefacts and monuments allows blind and visually impaired people to discover,understand and enjoy the beauty of Cultural Heritage. The reproduction of the artefactsusually starts with the 3D survey with reality-based techniques in order to obtain their metric,accurate digital copy. With a proper post-processing, the digital model is then set up ready forthe printing. The result is a physical model that can be touched and inspected, making the artvisible to everyone.This paper presents the pipeline followed for the 3D reproduction of the famous Michelangelo’sTomb of Giulio II, visible in San Pietro in Vincoli church in Rome. The photogrammetricsurvey is descripted and evaluated, and all the process followed to postprocess the 3D modelin order to make it countable for the 3D printing. A particular attention was given to theproblems occurred during the survey (lack of space, lights) and then the postprocessing relatedto the creation of different printed physical models. The fi nal models have been printed inaccomplish with the requests of the costumer, in order to make them suitable for blind people.

New technologies can help in documenting, preserving and disseminating cultural contexts. Although photogrammetry is a well-known technology for preserving cultural heritage, its combined use with 3D printing is worthwhile to simultaneously provide a digital twin for conservation and restoration purposes and for disclosure of Cultural Heritage. The possibility that 3D printing gives in the field of Cultural Heritage is wide and goes from the creation of small models for bookshops to scaled models for helping blind people to visualize sculptures or artistic artifacts through touch. They can also be valuable resources for all museum visitors allowing them to experience the monument or artefact. This paper presents the pipeline followed for the survey and the creation of high- and low-resolution models of the Tomb of Giulio II in Rome, providing on one hand the Superintendence with a 3D model useful for study and virtual restoration, and on the other blind people with an accurate 3D printed model for enjoying and understanding the monument. Each step of the process is explained highlighting the critical passages starting from the difficulties during the 3D survey to the creation of an accurate 3D reality-based model to the production of a valuable 3D printed model

Si ordinano le fonti per mostrare il potenziale dei modelli grafici che passano dall’interpretazione al controllo progettuale. L’articolo affonda le sue radici in una ricerca svolta dagli autori all’interno del gruppo “Archeotecnica” (www.archeotecnica.com), tutt’ora ancora in itinere. Tra i fini, l’opportunità d’identificare i canoni di una corretta “archeologia sperimentale”. La trattazione focalizza l’interesse sulla ricostruzione esecutiva di una lancia-sassi “palintona” i cui caratteri segnarono un’evoluzione importante per le prestazioni delle macchine da lancio (telecinetiche ellenistiche). Per motivate ragioni, si ritiene che armi simili siano state utilizzate nell’89 a.C. durante l’assalto di Silla all’antica città di Pompei. Le impronte balistiche rilevate sulla tratta settentrionale delle mura della città, sepolta nel 79 d.C. e dissepolta poco più di un secolo fa, permettono oggi la verifica del loro potenziale distruttivo. Il dimensionamento della reale lancia-sassi (balista), basato sul rilievo del “modiolo” (che sostiene e torce le matasse nervine spinto fin quasi al loro snervamento) unitamente al calcolo della gittata dei proietti, persegue la conoscenza necessaria alla realizzazione di prototipi certificati indirizzati ad allestimenti museali in-on-off situ.

The paper discusses the methodology followed to survey the Tomb of Julius II (Rome, 1545) and create high- and low-resolution 3D models to provide on the one hand, the Superintendency with a useful support for the study and virtual restoration of the surveyed work, and on the other hand, blind people with a digital twins, printed more and less accurately to be suitable for the use and differentiated understanding of the monument. Each step of the photogrammetric process employed is recalled discussing the quality of the 3D digital assets functional for the purposes mentioned above. The automated processes of next-generation photogrammetry are in fact aimed at obtaining polygonal 3D models mapped with real colour textures to derive metrically, topologically, and chromatically precise and accurate representations. The technique and method now established in the tradition of the scientific disciplinary sector of survey and representation, provide an opportunity to outline shared and interoperable investigation paths. These prove useful for stimulating inclusive projects and directing the evolution of the discipline in relation to communication and socio-cultural learning processes.

[EN] The paper presents Axis Strutture, patented by the authors, awarded with V:alere funds (VAnvitelli pER la ricErca 2020) for the establishment of an innovative start-up, now academic spin-off. It is based on the assemble of iron and wood with 'pins' (in Latin 'axis') threaded to ensure an economic profit in line with the Sustainable Development Goals, reviewing ancient technologies in the light of advanced research. The focus is on the structural connections of a construction system that clamps the steel frame elements with the wooden infill, allowing to assemble modular, prefabricated and flexible components customized on the design phase’s request. It provides effective emergency shelters assembled or dismantled as quickly as tents but more stable, healthier and comfortable. With a single star key, the steel uprights can be attested with wooden and similar tampons avoiding nails and screws which allows the total reuse of the components. The patented connections implement a new construction method promoting the self-construction of garden houses, leisure environments, bungalows, garages and quality housing modules, since they are resilient, resistant and with a controllable impact on the environment. The case study provides an opportunity to verify actions aimed at the implementation of Design for Adaptability strategies promoting virtuous life cycles that involves the entire community in sustainable models from an economic, environmental and social point of view., The case study develops the application potential of an idea patented by the authors awarded with the V: alere funds (VAnvitelli pER la ricErca 2020) for the establishment of an innovative start-up, now an academic spin-of

The use of 3D digitizing tools is becoming the base for subject-specific products, such as the orthopaedic production process of orthoses and prostheses. This paper aims at comparing the metrological behaviour of low-cost devices (Kinect 1 and 2 by Microsoft, Structure Sensor by Occipital) and high-resolution active sensors (O&P Scan by Rodin4D, NextEngine Ultra HD, Konica Minolta Vivid 9i, GOM ATOS II 400 and Artec Leo) for the survey of human body parts. A calibrated flat plane and a test-field composed of eight calibrated spheres of different radii and placed at different heights were used to evaluate the standard quality parameters (flatness, probing errors in form and size and the standard deviation) for each device as recommended by the VDI/VDE 2634 guidelines. Subsequently, three different parts of a mannequin were surveyed as samples of human body parts. The results demonstrated the higher accuracy of fixed devices with respect to handheld ones, among which Artec Leo and Structure Sensor provided a satisfying level of accuracy for the orthopaedic application. Moreover, the handheld devices enabled performing a fast reconstruction of the mannequin parts in about 20 s, which is acceptable for a person that has to remain as still as possible. For this reason, the Structure Sensor was further tested with five motion approaches which identified that smooth motion provides the lowest deviation and higher reliability. The work demonstrated the appropriateness of handheld devices for the orthopaedic application requirements in terms of speed, accuracy and costs.

Thanks to recent technological developments in 3D surveys, computer graphics and virtual reality, new scenarios have been opened for the documentation and enhancement of ancient sculptures. When not totally preserved, sculptures can be digitally reproduced, modified and visualized to simulate their physical or virtual reconstruction in a non-invasive way for specialists or for dissemination aims. The virtual sculptural reconstruction process starts usually from the 3D survey of real fragments, and then continues by integrating missing parts with 3D modelling techniques by means of source evaluation. Along with primary data sources (reality-based model), secondary data sources (photos, drawings and 3D models of similar sculptures) can be directly used in the reconstruction process. This approach has a double advantage of making the reconstruction activities easier and less arbitrary, contributing to a decrease in the degree of uncertainty for the sculptural reconstruction work, also thanks to many iconographic comparisons to ancient copies. Moreover, virtual reconstruction can be easily visualized alongside a scalable rendering system using open-source Web3D apps and platforms, accessing information, 3D models and descriptions in order to enhance the experience of artworks. Inspecting theoretical and technical approaches, this work aims at establishing how primary and secondary data sources can be effectively used in sculptural reconstruction workflows, and how 3D outputs can be applied to implement digital sculptural heritage exploitation for museums and cultural institutions. The statues of Aesculapius and Hygeia from the sanctuary of Isis in Lilybaeum (Marsala, Italy) were chosen as a case study.

The integration between 3D survey techniques and digital reconstruction allows to increase the knowledge and awareness of a Cultural Heritage. Its use becomes fundamental not only to study an ancient building or artefact, but also to communicate it to non-experts and make it more accessible and understandable. Basing the digital reconstruction on an accurate data such as a survey using reality-based techniques, allows to have an accurate and precise data base, as well as metrics, from which the reconstruction can be derived. The study of the geometry and characteristics of the site is favoured as the survey provides a metric and detailed basis of the characteristics of the building surveyed. This contribution aims at describing the methodology used to reconstruct the medieval cloister of ancient Oppido Mamertina (RC) in 3D, starting from the survey using a photogrammetric technique. The purpose of the work is to provide the Municipality and the Superintendency with accurate documentation of the site, as well as a navigable digital model that can be used for tourism purposes in view of the definition of a visit path for the enhancement of the site.

The article proposes a reflection on the architectural contents of the iconographies carved on a marble slab called slab of Perugia of the second half of the first century, kept in the archaeological museum of the Umbrian capital. The measurements expressed in fractions of anthropometric units in force at the time certify the legal nature of the document. The authors, moving from the graphic interpretation of the find to the design control of the three-dimensional reconstruction, take the opportunity to reflect on the opportunity to share VR and AR collaborative platforms, useful for promoting scientific knowledge in relation with the current civil commitment and to the economic development.

Conservation of Cultural Heritage is a key issue and structural changes and damages can inuence the mechanical behaviour of artefacts and buildings. The use of Finite Elements Methods (FEM) for mechanical analysis is largely used in modelling stress behaviour. The typical workow involves the use of CAD 3D models made by Non-Uniform Rational B-splines (NURBS) surfaces, representing the ideal shape of the object to be simulated. The use of Finite Elements Analysis (FEA) for ancient structures and artefacts has recently shown great potentialities. For Cultural Heritage objects, altered by the time passed since their original creation, the representation with a schematic CAD model may introduce an excessive level of approximation leading to wrong simulation results. Nowadays, 3D documentation of CH has been widely developed through reality-based approaches, but the models are not suitable for a direct use in FEA: the mesh has in fact to be converted to volumetric, and the density has to be reduced since the computational complexity of a FEA grows exponentially with the number of nodes. The focus of this work is to present a new method aiming at generate the most accurate 3D representation of a real artefact from highly accurate 3D digital models derived from reality-based techniques, maintaining the accuracy of the high-resolution polygonal models in the solid ones. The approach proposed is based on a wise use of retopology procedures and a transformation of this model to a mathematical one made by NURBS surfaces suitable for being processed by volumetric meshes typically embedded in standard FEM packages. The strong simplication with little loss of consistency possible with the retopology step is used for maintaining as much coherence as possible between the original acquired mesh and the simplied model, creating in the meantime a topology that is more favourable for the automatic NURBS conversion. This allows to obtain FEA results that are closer to the actual mechanical behaviour of the analysed heritage asset.

The meaning of an “open” approach in archaeology today probably implies many different, disconnected and even contrasting activities [...]

Reality-based 3D techniques and Finite Element Analysis share the way the object under investigation is discretized. Although their purpose, the generation methods and the quality metrics are dierent, both of them ground on the concept of mesh. Unfortunately, a mesh derived from a reality-based technique are not suitable to be used in a nite element solver directly. This paper aims at comparing dierent methods to prepare computational mesh of geometries derived from non-contact reality-based technologies. A benchmark test object has been acquired with dierent devices, a triangulation laser scanner, a multi-stripe triangulation scanner and a digital camera, and post processed in order to x artifacts. Then, two dierent decimation approaches have been used: a triangular simplication and retopology. The acquired geometry, before and after the simplications, has been compared with a CAD model employed as reference: mean and standard deviation between the nominal and the acquired geometries have been tracked. Finally, a tensile test has been simulated making use of a general-purpose nite element analysis software and the results have been compared with the exact solution.

Reverse Engineering has been exploited for several application, e.g measuring and inspection, customt design, cultural heritage. The result of this process is a 3D representation of the targeted object, usually encoded in an unstructured triangulated surface fashion (e.g. an STL le). Going beyond the mere visualization purpose and focusing on engineering products, prediction of mechanical performances is often required, especially for items critical from a structural perspective. Finite Method Analysis (FEA) is a de-facto standard to evaluate mechanical performances, both in academia and industry, but the meshes derived from reverse engineering techniques are not suitable for direct use in FEA solver. In those cases, a proper degree of accuracy, precision and reliability throughout the whole pipeline have to be guaranteed, from the acquisition of the geometry to the analysis of the nal result. Regardless the reverse engineering technology chosen, the standard pipeline requires the acquisition of the chosen object and the post process of the 3D model obtained in order to have a closed 3D mesh. The most important and thorny phase is the one related to the topological check of the 3D mesh and its simplication to obtain a proper model, suitable to be then translated in a computational grid for FEA. The problem is not new in literature [4] but researches have been focused more on large items (e.g. buildings). Firstly, the order of magnitude of the relevant feature is di erent: talking about architectural items, small features, i.e. less than 1mm, are negligible. Secondly, similar researches conducted so far don't evaluate FEA results systematically. This paper aims at comparing dierent methodologies in order to prepare computational mesh of geometries derived from reverse engineering technologies. A benchmark case, i.e. a structural-steel parallelepiped, has been chosen in order to have complete control over the variables involved in the process (both during the reverse engineering and the FEA). The test object has been acquired with a laser scanner and post processed in order to x artifacts. Once the mesh is closed and error-free, two dierent methodology for simplication have been used: a triangular simplication and retopology. The acquired geometry, before and after the simplications, has been compared with the reference model (i.e. a 3D geometry created using CAD geometric primitive): mean and standard deviation between the baseline model and the acquired geometries has been tracked. Finally, a tensile test has been simulated making use of a FEA software and the results have been compared with the theoretical solution.

Finite Elements Analysis (FEA) is widely used for modelling stress behaviour in anymechanical system. The processing workflow starts from CAD 3D models representing the idealshape of the object to be simulated. Such models are typically made of mathematical elementsdefining its geometrical components. Those are pre-processed before the simulation for creatinga volumetric mesh out of the CAD model. Recently the use of FEA has also been extended tothe simulation of ancient structures and artefacts, revealing significant potentialities for theconservation of Cultural Heritage. Unlike modern mechanical systems, heritage objects areusually altered by the time passed since their original creation, and the representation with aschematic CAD model may introduce an excessive level of approximation leading to wrongsimulation results. In the last two decades, 3D documentation of CH has been developed throughreality-based approaches. However, the related mesh models of the exterior surfaces are notproper for direct use in FEA. Such high-resolution surface meshes has to be converted tovolumetric meshes made of tetrahedral or hexahedral elementary volumes and a limited numberof external and internal nodes. The focus of this paper is on a new method aiming at generatingthe best possible 3D solid representation of a real artefact from its accurate reality-based surfacemodel by reducing its number of nodes of several orders of magnitude while maintaining ageometrical coherence in the order of the measurement uncertainty of the 3D capturing techniqueused. The approach proposed is based on wise use of retopology procedures and a transformationof this retopologized model to a mathematical one made by NURBS surfaces, suitable for beingprocessed by a volumetric mesh generator typically embedded in any standard FEM package.The resulting volumetric mesh allows obtaining FEA of ancient structures, providing a far betteraccurate simulation than those attainable by a rough CAD redrawing of the heritage asset ofinterest. (17) (PDF) A New Methodology for the Structural Analysis of 3D Digitized Cultural Heritage through FEA. Available from: https://www.researchgate.net/publication/325833167_A_New_Methodology_for_the_Structural_Analysis_of_3D_Digitized_Cultural_Heritage_through_FEA [accessed Oct 25 2022].

The paper presents results of the project: Cultural Heritage Through Time (CHT 2, http://cht2-project.eu) realized accomplished within the framework of the “Joint Programming Initiative in Cultural Heritage” JPI-CH (http://www.jpi-culturalheritage.eu) by an international consortium: Politecnico di Milano (IT), Newcastle University (UK), Salamanca University (ES), and Stanislaw Staszic Scientific Association SSSA (a non-profit organization), (PL). The aim of the project was the integration of 3D models of buildings, cities and landscapes for monitoring and preservation of the cultural heritage. The research was conducted on three levels of detail according to the CityGML standard: LoD0 – regional, landscape scale, LoD1/LoD2 – urban scale, LoD3 – architectural scale, level of detail - building outside. Basing of this assumption, four test sites were selected: i. the city centre of Milan (IT) – urban scale, ii. the medieval walls and the historic centre of Avila (ES) - urban/architecture scale, iii. Hadrian’s Wall and its landscape (UK) – landscape scale, iv. the Fortress Cracow Krakow (PL) - architectural scale. Final 4D models were published on the Internet. The paper presents state-of-the art of the technology of 4D models sharing on the internet. 4D models were understood as 3D models solid one and point clouds changing through the time. Results of the practical initial tests of different software (commercial: Hexagon and CityEngine from ESRI and open-source: 3DHOP and Potree) are also shown. Web site: https://cht2.eu was created where the 4D models are placed for all the project partners.

18 p. Cultural Heritage (CH) is recognised as being of historical, social, and anthropological value and is considered as an enabler of sustainable development. As a result, it is included in the United Nations’ Sustainable Development Goals (SDGs) 11 and 8. SDG 11.4 emphasises the protection and safeguarding of heritage, and SDG 8.9 aims to promote sustainable tourism that creates jobs and promotes local culture and products. This paper briefly reviews the geoinformatics technologies of photogrammetry, remote sensing, and spatial information science and their application to CH. Detailed aspects of CH-related SDGs, comprising protection and safeguarding, as well as the promotion of sustainable tourism are outlined. Contributions of geoinformatics technologies to each of these aspects are then identified and analysed. Case studies in both developing and developed countries, supported by funding directed at the UN SDGs, are presented to illustrate the challenges and opportunities of geoinformatics to enhance CH protection and to promote sustainable tourism. The potential and impact of geoinformatics for the measurement of official SDG indicators, as well as UNESCO’s Culture for Development Indicators, are discussed. Based on analysis of the review and the presented case studies, it is concluded that the contribution of geoinformatics to the achievement of CH SDGs is necessary, significant and evident. Moreover, following the UNESCO initiative to introduce CH into the sustainable development agenda and related ICOMOS action plan, the concept of Sustainable Cultural Heritage is defined, reflecting the significance of CH to the United Nations’ ambition to “transform our world”. SI

The ancient city centers often contain traces of monuments almost completely disappeared, whose few remains are hidden by modern buildings. This is the case for many monumental buildings of the Roman period in Italian cities, that have almost disappeared over time being gradually dismantled for the reusing their construction materials, leaving space to a dense urbanization. Knowledge of such monuments is often approximate and based on historical memories of various kinds. In such situations, three-dimensional surveys and digital 3D modelling reconstructions can be of great support for scientific-archaeological research and for providing a scientifically supported image of cultural heritage sites. This paper shows the work on the emblematic example of the late Roman Circus of Milan, an impressive monument of about 450x85 meters, built when Mediolanum used to be capital of the Western Roman Empire (286-402 A.D). This fact is nowadays almost unknown to most citizens of Milan. The diachronic reconstruction approach is used in order to show the monument in his current state and in his presumed past aspect. The reconstruction is based on a proper mix of quantitative data originated by 3D surveys at present time, and historical sources like ancient maps, drawings, archaeological reports, archaeological restrictions decrees and old photographs. In this panorama, the georeferenced acquired data of the remains play a key role in order to validate the previous reconstruction of the building and to define some fixed points to hypothesize a reliable reconstruction of the area in different historical periods. The experimental activity is defined by the project Cultural Heritage Through Time - CHT2 (http://cht2-project.eu), funded in the framework of the Joint Programming Initiative on Cultural Heritage (JPI-CH) of the European Commission.

This paper presents the methodological approach and the actual workflow for creating the 3D digital reconstruction in time of the ancient Roman Circus of Milan, which is presently covered completely by the urban fabric of the modern city. The diachronic reconstruction is based on a proper mix of quantitative data originated by current 3D surveys and historical sources, such as ancient maps, drawings, archaeological reports, restrictions decrees, and old photographs. When possible, such heterogeneous sources have been georeferenced and stored in a GIS system. In this way the sources have been analyzed in depth, allowing the deduction of geometrical information not explicitly revealed by the material available. A reliable reconstruction of the area in different historical periods has been therefore hypothesized. This research has been carried on in the framework of the project Cultural Heritage Through Timeâ CHT2, funded by the Joint Programming Initiative on Cultural Heritage (JPI-CH), supported by the Italian Ministry for Cultural Heritage (MiBACT), the Italian Ministry for University and Research (MIUR), and the European Commission.

This paper shows a VR application for explaining the meaning of the various pictograms and hieroglyphs typical of the ancient Egypt funerary rituals. The interaction between the user and the 3D environment is obtained through an Oculus Rift head mounted stereoscopic display, coupled with a Leap Motion controller as input device that digitize in real-time the hands of the end-user, displaying a skeletal version of those in the virtual environment. The interactive application is based on Unity3D and it explains the details of the rituals starting from the crate of an Egyptian sarcophagus and some typical funerary objects like the Heart Scarab and the Ushabty.

The goal of the 3D-ICONS European Project is to provide EUROPEANA ( www.europeana.eu ) with accurate 3D models of architectural and archaeological monuments and buildings of remarkable cultural importance. The purpose of this paper is to describe the specific processing pipeline that has been set for digitizing a significant part of the Civic Archaeological Museum in Milan (Italy). All the technical and logistic aspects needed for capturing 3D models in a Museum environment, the implication with IPR, and the metadata acquisition, are covered. The main issue is generating a good result by the technical point of view, minimizing the impact on the usual Museum activity during the 3D capturing operations, shortening in the meantime the processing time to the minimal allowed by the different applicable techniques. This condition has led different choices related to the survey technologies (laser scanning and image based modeling) and the related data processing. Both technical and descriptive metadata have been collected for each item acquired, for generating a record of data searchable on EUROPEANA, with the addition of new metadata not defined in the minimal record, for making traceable the path leading to the generated digital content. The paper gives a general discussion of such issues with some specific examples referred to the large set of 3D objects digitized within the 3D-ICONS project.

Il contributo pone in relazione la necropoli longobarda di Romans d'Isonzo con i percorsi stradali di epoca tardo antica e alto medievale, utilizzando le metodologie dell'analisi spaziale, in particolare la cost surface analysis e la viewshed analysis. E' stato creato un modello digitale del terreno, sulla base delle mappe catastali attuali e storiche, su cui, con l'ausilio del GIS, si sono inseriti i dati. Questi ultimi sono stati poi messi a confronto con la ricostruzione dei percorsi effettuata dagli storici Luciano Bosio e Mario Brozzi.

The paper presents a critical review and analysis of dense image matching algorithms. The analyzed algorithms stay in the commercial as well open-source domains. The employed datasets include scenes pictured in terrestrial and aerial blocks, acquired with convergent and parallel-axis images and different scales. Geometric analyses are reported, comparing the dense point clouds with ground truth data.

Conservation of Cultural Heritage is a key issue and structural changes and damages can influence the mechanical behaviour of artefacts and buildings. The use of Finite Elements Methods (FEM) for mechanical analysis is largely used in modelling stress behaviour. The typical workflow involves the use of CAD 3D models made by Non-Uniform Rational B-splines (NURBS) surfaces, representing the ideal shape of the object to be simulated. Nowadays, 3D documentation of CH has been widely developed through reality-based approaches, but the models are not suitable for a direct use in FEA: the mesh has in fact to be converted to volumetric, and the density has to be reduced since the computational complexity of a FEA grows exponentially with the number of nodes. The focus of this paper is to present a new method aiming at generate the most accurate 3D representation of a real artefact from highly accurate 3D digital models derived from reality-based techniques, maintaining the accuracy of the high-resolution polygonal models in the solid ones. The approach proposed is based on a wise use of retopology procedures and a transformation of this model to a mathematical one made by NURBS surfaces suitable for being processed by volumetric meshers typically embedded in standard FEM packages. The strong simplification with little loss of consistency possible with the retopology step is used for maintaining as much coherence as possible between the original acquired mesh and the simplified model, creating in the meantime a topology that is more favourable for the automatic NURBS conversion.

In this paper, a series of topics, concerning acquisition, communication, and the analysis of buildings will be discussed. In particular, a strategy aimed at exploiting the visual potentials of reality-based models, will be described inside render engines, real-time applications, as well as their role for the production of conventional drawing for documenting and studying built heritage. This methodology is inspired by pipelines coming from computer-generated imagery (CGI) and the video game industry: areas of research that are progressively showing an increasing interest towards the world of photogrammetry remote sensing, in particular for the new possibilities offered by Structure from Motion (SfM)/Multi View Stereo (MVS) in terms of automatic texturing of complex shapes. Quad-dominant remeshing, displaced subdivision surfaces, and accurate interactive/ automatic parametrization are the main points of this workflow, whose final goal is the achievement of multipurpose models, which are capable to comply with graphic codes of traditional survey, as well as semantic enrichment, and, last but not least, data compression/portability and texture reliability under different lighting conditions.

The paper presents an analysis of the 3D data quality generated from small-medium objects by well-known automatic photogrammetry packages based on Structure from Motion (SfM) and Image Matching (IM). The work aims at comparing different shooting configurations and image redundancy, using as high-quality reference the 3D data acquired by triangulation-based laser scanners characterized by a low measurement uncertainty. Two set of tests are presented: i) a laboratory 3D measurement made with the two active and passive approaches, where the image-based 3D acquisition makes use of different camera orientations leading to different image redundancy; ii) a 3D digitization in the field with an industrial laser scanner and two sets of images taken with different overlap levels. The results in the field confirm the relationship between measurement uncertainty and image overlap that emerged in the Lab tests.

The goal of the reported project is to test and evaluate 3D surveying and modelling methods to document the remaining ancient byzantine city walls of the archaeological site of Aquileia in Friuli Venezia Giulia, Italy. The objectives are threefold: (1) to use 3D data to create maps, façades and sections that provide information useful for archaeological purposes such as the investigation of architectural construction techniques or construction phases, (2) to evaluate and compare photogrammetric and laser scanner data in order to identify the advantages and disadvantages of the two 3D surveying techniques for archaeological applications and needs and (3) to draw broader conclusions about the applicability of photogrammetry and laser scanning for documenting and analysing ancient walls within a particular set of environmental circumstances. The paper presents the employed 3D surveying techniques, the obtained 3D results and 2D products and some critical comments.