The implementation of BIM methodologies for historical buildings presupposes not only the collection of data and information related to its geometric configuration and to the technical parameters of its constituent elements, but more generally the identification of those semantic values which make it part of the historical-cultural heritage shared in a specific context. It is therefore essential that the modelling objectives are explicitly defined in relation to the specific BIM uses required, in order to avoid risks of over-modelling. This paper proposes a process of geometric validation of building information models of high morphological complexity implemented through Scan-to-BIM procedures. By means of a controlled and interoperable workflow, a chain of software applications is defined that is able to determine the level of geometric accuracy (LOA) of the information model with respect to the numerical model derived from the point cloud. Two case studies of H-BIM modelling of historical monumental complexes dating back to the Romanesque period in Sardinia (Italy) are illustrated: the churches of Sant'Efisio a Nora (Cagliari) and Santa Maria del Regno (Sassari). In the discussion of the results, the need for a prior definition of modelling strategies in relation to the expected BIM uses is highlighted. The digital survey was carried out as a part of the research project titled, “The Romanesque and the territory. Construction materials of the Sardegna Giudicale”, and coordinated by prof. Stefano Columbu. The BIM model was developed by a students’ team as part of the teaching activities of the Architectural Drawing course at the School of Engineering, University of Florence. The imagines are extracted from the drawings of the students, Valeria Siddi, Elena Pastorelli, Liuba Gabrielli, Simone Riccio, Elisa Ricotti.
Publisher: Multidisciplinary Digital Publishing Institute
The application of protective coatings is an effective preventive strategy to avoid metal corrosion. Constant monitoring of the coating’s quality is fundamental for the successful preservation of the metallic objects by reducing their interaction with corroding agents. Their evaluation over time helps to identify failure at early stages and promote their removal and substitution. Several methods have been employed for coating evaluation (i.e., chemical analysis, thickness and homogeneity investigation). In this paper, we compare three methods—Optical Coherence Tomography (OCT), Confocal Raman Microspectroscopy (CRM), and Eddy Currents (ECs)—to evaluate thickness values and coating integrity. The results from the two optical techniques (CRM and OCT) agree, being able to detect the inhomogeneity of the layer on a micron scale but requiring correction to account for the refraction phenomenon. The Eddy Current is a fast and efficient method for thickness estimation, providing data with millimetric lateral resolution.
Jiamei Lin; Anders Svensson; Christine S. Hvidberg; Johannes Lohmann; Steffen Kristiansen; Dorthe Dahl-Jensen; Jørgen Peder Steffensen; Sune Olander Rasmussen; Eliza Cook; Helle Astrid Kjær; +8 more
Jiamei Lin; Anders Svensson; Christine S. Hvidberg; Johannes Lohmann; Steffen Kristiansen; Dorthe Dahl-Jensen; Jørgen Peder Steffensen; Sune Olander Rasmussen; Eliza Cook; Helle Astrid Kjær; Bo M. Vinther; Hubertus Fischer; Thomas Stocker; Michael Sigl; Matthias Bigler; Mirko Severi; Rita Traversi; Robert Mulvaney;
Countries: United Kingdom, Denmark, Italy, Switzerland, United Kingdom, Switzerland, Denmark
Large volcanic eruptions occurring in the last glacial period can be detected by their accompanying sulfuric acid deposition in continuous ice cores. Here we employ continuous sulfate and sulfur records from three Greenland and three Antarctic ice cores to estimate the emission strength, the frequency and the climatic forcing of large volcanic eruptions that occurred during the second half of the last glacial period and the early Holocene, 60–9 kyr before 2000 CE (b2k). Over most of the investigated interval the ice cores are synchronized, making it possible to distinguish large eruptions with a global sulfate distribution from eruptions detectable in one hemisphere only. Due to limited data resolution and large variability in the sulfate background signal, particularly in the Greenland glacial climate, we only list Greenland sulfate depositions larger than 20 kg km−2 and Antarctic sulfate depositions larger than 10 kg km−2. With those restrictions, we identify 1113 volcanic eruptions in Greenland and 737 eruptions in Antarctica within the 51 kyr period – for which the sulfate deposition of 85 eruptions is found at both poles (bipolar eruptions). Based on the ratio of Greenland and Antarctic sulfate deposition, we estimate the latitudinal band of the bipolar eruptions and assess their approximate climatic forcing based on established methods. A total of 25 of the identified bipolar eruptions are larger than any volcanic eruption occurring in the last 2500 years, and 69 eruptions are estimated to have larger sulfur emission strengths than the Tambora, Indonesia, eruption (1815 CE). Throughout the investigated period, the frequency of volcanic eruptions is rather constant and comparable to that of recent times. During the deglacial period (16–9 ka b2k), however, there is a notable increase in the frequency of volcanic events recorded in Greenland and an obvious increase in the fraction of very large eruptions. For Antarctica, the deglacial period cannot be distinguished from other periods. This confirms the suggestion that the isostatic unloading of the Northern Hemisphere (NH) ice sheets may be related to the enhanced NH volcanic activity. Our ice-core-based volcanic sulfate records provide the atmospheric sulfate burden and estimates of climate forcing for further research on climate impact and understanding the mechanism of the Earth system.
The interest in high-resolution semantic 3D models of historical buildings continuously increased during the last decade, thanks to their utility in protection, conservation and restoration of cultural heritage sites. The current generation of surveying tools allows the quick collection of large and detailed amount of data: such data ensure accurate spatial representations of the buildings, but their employment in the creation of informative semantic 3D models is still a challenging task, and it currently still requires manual time-consuming intervention by expert operators. Hence, increasing the level of automation, for instance developing an automatic semantic segmentation procedure enabling machine scene understanding and comprehension, can represent a dramatic improvement in the overall processing procedure. In accordance with this observation, this paper aims at presenting a new workflow for the automatic semantic segmentation of 3D point clouds based on a multi-view approach. Two steps compose this workflow: first, neural network-based semantic segmentation is performed on building images. Then, image labelling is back-projected, through the use of masked images, on the 3D space by exploiting photogrammetry and dense image matching principles. The obtained results are quite promising, with a good performance in the image segmentation, and a remarkable potential in the 3D reconstruction procedure. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XLVI-2/W1-2022 ISSN:2194-9034 ISSN:1682-1777 ISSN:1682-1750
Nicole Manfredda; Paola Buscaglia; Paolo Gallo; Matilde Borla; Sara Aicardi; Giovanna Poggi; Piero Baglioni; M. Nervo; Dominique Maria Scalarone; Alessandro Borghi; +3 more
Nicole Manfredda; Paola Buscaglia; Paolo Gallo; Matilde Borla; Sara Aicardi; Giovanna Poggi; Piero Baglioni; M. Nervo; Dominique Maria Scalarone; Alessandro Borghi; Alessandro Re; Laura Guidorzi; Alessandro Lo Giudice;
This contribution focuses on the conservation of an Egyptian wooden sculpture (Inventory Number Cat. 745) belonging to the Museo Egizio of Torino in northwest Italy. A preliminary and interdisciplinary study of constituent painting materials and their layering is here provided. It was conducted by means of a multi-technique approach starting from non-invasive multispectral analysis on the whole object, and subsequently, on selected micro-samples. In particular, visible fluorescence induced by ultraviolet radiation (UVF), infrared reflectography (IRR) and visible--induced infrared luminescence were used on the whole object. The micro-samples were analysed by means of an optical microscope with visible and UV light sources, a scanning electron microscope (SEM) with an energy-dispersive X-ray spectrometer (EDX), Fourier transform infrared (FT-IR) spectrometer, pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS) and micro-particle induced X-ray emission (PIXE). The characterization of the painting materials allowed the detection of Egyptian blue and Egyptian green, and also confirmed the pertinence of the top brown layer to the original materials, which is a key point to design a suitable surface treatment. In fact, due to the water sensitiveness of the original materials, only few options were available to perform cleaning operations on this artwork. To setup the cleaning procedure, we performed several preliminary tests on mockups using dry cleaning materials, commonly used to treat reactive surfaces, and innovative highly water retentive hydrogels, which can potentially limit the mechanical action on the original surface while proving excellent cleaning results. Overall, this study has proved fundamental to increase our knowledge on ancient Egyptian artistic techniques and contribute to hypothesize the possible provenance of the artefact. It also demonstrated that polyvinyl alcohol-based retentive gels allow for the safe and efficient cleaning of extremely water sensitive painted surfaces, as those typical of ancient Egyptian artefacts.
Ice core dating is the first step for a correct interpretation of climatic and environmental changes. In this work, we release the dating of the uppermost 197 m of the 250 m deep GV7(B) ice core (drill site, 70∘41′ S, 158∘52′ E; 1950 m a.s.l. in Oates Land, East Antarctica) with a sub-annual resolution. Chemical records of NO3-, MSA (methanesulfonic acid), non-sea-salt SO42- (nssSO42-), sea-salt ions and water stable isotopes (δ18O) were studied as candidates for dating due to their seasonal pattern. Different procedures were tested but the nssSO42- record proved to be the most reliable on the short- and long-term scales, so it was chosen for annual layer counting along the whole ice core. The dating was constrained by using volcanic signatures from historically known events as tie points, thus providing an accurate age–depth relationship for the period 1179–2009 CE. The achievement of the complete age scale allowed us to calculate the annual mean accumulation rate throughout the analyzed 197 m of the core, yielding an annually resolved history of the snow accumulation on site in the last millennium. A small yet consistent rise in accumulation rate (Tr = 1.6, p<0.001) was found for the last 830 years starting around mid-18th century.
[ES] El ensayo, el primero de dos escritos, reconstituye los acontecimientos de la generación de historiadores que, entre los años 70 y mediados de los 80, estudiaron e interpretaron las obras escritas y proyectadas por Le Corbusier. Esta imagen forma parte de la lectura de las diferentes fases de restauración de la Villa Savoye dirigidas por el arquitecto jefe Ivan Gury tras una primera realización de Jean Dubuisson, abriendo una época de interminables restauraciones de autor de lo moderno. Los autores también abordan la compleja cuestión de la interpretación de las obras de Le Corbusier en la fase de formación de la historia de la arquitectura contemporánea, cuando las fuentes están casi universalmente disponibles y la literatura sobre el tema se dispara. El texto explora materiales y documentos inéditos, ofreciendo una nueva interpretación tanto de la Villa Savoye como de los textos sobre el maestro franco-suizo. [FR] L’essai, le premier de deux écrits, reconstitue les événements de la génération d’historiens qui, entre les années 70 et le milieu des années 80, a étudié et interprété les œuvres de Le Corbusier, écrites et projetées. Cette image s’inscrit dans la lecture des différentes phases de restauration de la villa Savoye menée par l’architecte en chef Ivan Gury après un premier achèvement par Jean Dubuisson, ouvrant une saison de restaurations infinies du moderne d’auteur. Les auteurs abordent également la question complexe de l’interprétation des œuvres de Le Corbusier dans la phase de formation de l’histoire de l’architecture contemporaine, lorsque les sources sont presque toutes accessibles et que la littérature sur le sujet explose. Le texte explore des matériaux et des documents inédits, offrant une nouvelle interprétation à la fois de la villa Savoye et des textes sur le maître franco-suisse. [EN] The essay, the first of two writings, reconstructs the events of the generation of historians who between the seventies and mid-eighties studied and interpreted the written and designed works by Le Corbusier. This picture is part of the reading of different phases of the restoration of villa Savoye conducted by architect en chef Ivan Gury after the first operation by Jean Dubuisson, leading to a season of infinite authorial restorations of the modern. The authors deal with the complex issue of the interpretation of Le Corbusier’s works during the formation phase of the history of contemporary architecture, when the sources are almost all accessible and the literature on the subject explodes. The text investigates unpublished materials and documents, offering a new interpretation both of the villa Savoye and of the texts on the French-Swiss master.
Abstract The scientific community is hardly working to propose reliable methodologies of analysis and non-invasive technologies of investigation to assess the current state of conservation of historic buildings to verify their ability to resist future threats. These structures, mostly made of masonry, are difficult to assess due to the heterogeneity of materials and their mechanical behavior, but it is vital to preserve this invaluable cultural heritage by suitable structural assessment techniques. A great deal of research attention has been paid to monitoring their structural health; in many recent publications new advanced technological methods have been provided such as cheaper sensors, wireless connections, non-contact surveys and continuous monitoring. A bibliometric study has shown that more than half of the papers on Structural Health Monitoring (SHM) and Nondestructive Testing (NDT) on masonry have been published between 2018 and 2020, and 30% of those published in 2020 were on ‘slender’ elements like towers, chimneys or minarets. This paper presents a wide-ranging review of static and dynamic studies published on SHM and NDT of slender masonry structures summarizing and discussing the different experimental techniques used. With respect to the dynamic testing, Operational Modal Analysis (OMA) by accelerometers is the mostly frequent used technique by scholars, but other promising methods such as radar interferometry are also reported. This overall discussion is concluded with a short review of some examples on numerical structural health assessment and signal processing tools. An inclusive list of papers is provided describing the most important slender masonry structures characteristics, natural frequencies, experimental and numerical techniques employed and reference values. This paper, set on a practical perspective, is expected to be of interest to those researchers and practitioners who require an extensive and up-to-date review of this topic.
Rome Transformed' is a five-year ERC funded research project that began in 2019 with the aim of developing an understanding of Rome and its place in cultural change across the Mediterranean world by mapping political, military and religious changes to the eastern Caelian from the first to eight centuries. The project has brought together a team of specialists in non-invasive methodologies for the investigation of complex modern urban environments. Beginning with extensive archival and bibliographic research, the project is conducting detailed structural analysis of all the standing monuments in the area. This includes structures such as the Aurelian Walls, the Claudio-Neronian aqueduct and the Sessorian Palace complex. A central component of these investigations is the high-resolution geophysical prospection of the study area which covers around 13.7km2 in central Rome. The use of these non-invasive methodologies in central Rome led to several challenges, in particular the significant topographical changes that have occurred since antiquity. To the west, underneath the Basilica of Saint John Lateran, nine metres of vertical stratigraphy are preserved, ranging from Republican houses at the lower level through to the Castra Nova of Septimius Severus and the Constantine Basilica. This paper, as well as presenting preliminary results of the geophysical surveys, will also discuss some of the solutions for geophysical prospection in complex urban environments. For the study of the Eastern Caelian, the collation of information regarding previous excavations has been fundamental, which has been greatly assisted by a collaboration with the municipal authority archaeological service and access to their ArcheoSITAR database.
At present, macro X-ray fluorescence (MA-XRF) is one of the most essential analytical methods exploited by heritage science. By providing spatial distribution elemental maps, not only does it allow for material characterisation but also to understand, or at least to have a likely idea of, the production techniques of an analysed object. INFN-CHNet, the Cultural Heritage Network of the Italian National Institute of Nuclear Physics, designed and developed a MA-XRF scanner aiming to be a lightweight, easy to transport piece of equipment for use in in situ measurements. In this study, the INFN-CHNet MA-XRF scanner was employed for the analysis of a painting by the Flemish artist Rogier van der Weyden. The painting belongs to the collection of the Uffizi gallery in Florence and was analysed during conservation treatments at the Opificio delle Pietre Dure, one of the main conservation centres in Italy. The research aims were to characterise the materials employed by the artist and to possibly understand his painting technique. Although MA-XRF alone cannot provide a comprehensive characterisation, it nonetheless proved to be an invaluable tool for providing an initial overview or hypothesis of the painting materials and techniques used.