1,721,054 research outputs found
Tecniche digitali per il rilievo, la modellazione tridimensionale e la rappresentazione nel campo dei beni culturali
Full text linkLe soluzioni tecnologiche rese oggi disponibili dalle discipline della moderna Geomatica, offrono opportunità di grande interesse per il rilevamento nel settore dei Beni Culturali, sia per quanto riguarda il momento primario del rilievo, cioè la fase di acquisizione del dato metrico, sia per quanto concerne la questione della rappresentazione per oggetti di interesse archeologico, artistico, architettonico. Lo studio oggetto della presente tesi si propone, sulla base di numerose esperienze maturate nel corso del Dottorato dal Laboratorio di Topografia e Fotogrammetria del DISTART, di affrontare e approfondire le problematiche connesse all’utilizzo della fotogrammetria digitale e del laser a scansione terrestre per applicazioni nell’ambito dei Beni Culturali. La ricerca condotta è prettamente applicata, quindi è stata primaria l’esigenza di avere a disposizione reali casi di studio su cui sperimentare le tecniche di interesse; è però importante sottolineare che questo è un campo in cui ogni esperienza presenta proprie caratteristiche e peculiarità che la rendono interessante e difficilmente descrivibile con schemi convenzionali e metodologie standardizzate, quindi le problematiche emerse hanno di volta in volta indirizzato e spinto la ricerca all’approfondimento di certi aspetti piuttosto che altri. A tal proposito è stato evidenziato dalle esperienze effettuate che il campo dei Beni Culturali è forse il più emblematico delle potenzialità rese oggi disponibili dalle moderne tecnologie della Geomatica, e soprattutto dalle possibilità offerte da un approccio integrato e multi – disciplinare di tecniche e tecnologie diverse; per questo nell’Introduzione si è voluto sottolineare questo aspetto, descrivendo l’approccio metodologico adottato in molti lavori in contesto archeologico, che include generalmente diverse tecniche integrate tra loro allo scopo di realizzare in modo veloce e rigoroso un rilievo multi – scala che parte dal territorio, passa attraverso l’area del sito archeologico e degli scavi, ed arriva fino al singolo reperto; questo approccio è caratterizzato dall’avere tutti i dati e risultati in un unico e ben definito sistema di riferimento. In questa chiave di lettura l’attenzione si è poi focalizzata sulle due tecniche che rivestono oggi nel settore in esame il maggiore interesse, cioè
fotogrammetria digitale e laser a scansione terrestre. La struttura della tesi segue le fasi classiche del processo che a partire dal rilievo porta alla generazione dei prodotti di rappresentazione; i primi due capitoli, incentrati sull’acquisizione del dato metrico, riguardano quindi da un lato le caratteristiche delle immagini e dei sensori digitali, dall’altro le diverse tipologie di sistemi laser con le corrispondenti specifiche tecniche; sempre nei primi capitoli vengono descritte le caratteristiche metodologiche e tecnico – operative e le relative problematiche delle due tipologie di rilievo. Segue un capitolo sulle procedure di calibrazione delle camere digitali non professionali, imperniato sull’utilizzo di software diversi, commerciali e sviluppati in house per questo scopo, prestando attenzione anche agli strumenti che essi offrono in termini di risultati ottenibili e di controllo statistico sugli stessi. La parte finale della tesi è dedicata al problema della rappresentazione, con l’obiettivo di presentare un quadro generale delle possibilità offerte dalle moderne tecnologie: raddrizzamenti, ortofoto, ortofoto di precisione e infine modelli tridimensionali foto – realistici, generati a partire sia da dati fotogrammetrici sia da dati laser
Use of historical images for the documentation and the metrical study of Cultural Heritage by means of digital photogrammetric techniques
No full textThe paper is related to a multi-disciplinary project started in 1999, within a collaboration established between the University of Bologna and the Archaeological Superintendence of Pompeii. In the frame of this project was activated a rigorous survey, by the integration of different geomatic techniques (GPS, Laser Scanning, Photogrammetry, Visual Reality), of the most significant nymphaea of Ercolano and Pompeii (Naples); these are elements of remarkable archaeological and artistic value and presenting various geometric characteristics, needing a very accurate description of the decorative apparatus, often entrusted to particularly complex and rich mosaics.
In particular are here described the studies conducted about the Lararium from the “House of the Skeleton” in Ercolano.
This object is interesting for this kind of study because it presents some static problems and it has suffered during the excavations many interventions and changes, until the complete disassembly and successive replacement in situ.
Three images of the 1927-1928 periods were chosen with the aim of creating a historical 3D model of the object, comparable with the actual model, derived by the photogrammetric survey conducted in the 2006 campaign.
After an experimentation phase necessary to define the most suitable methods to perform the images calibration (single or multi photo, with the use of geometric constraints or also with the use of control points), a valid set of parameters was found and a complete model of the object was reconstructed, representive of the metric and qualitative conditions in this epoch.
The dimensional comparison between the two temporal situations (historical and actual) has also permitted qualitative and quantitative considerations about the differences, offering a very important tool for the evaluation of the past restorations and useful also to plan all the future interventions
A View from Above. Geodesy and Satellite Image Analysis in the Islahiye Valley
No full textThe paper presents some of the surveying experiences, mainly at territorial
scale, performed by the authors at the site of Tilmen Höyük, in collaboration with
archaeologists and researchers from other fields. Satellite imagery, multi-scale digital
Photogrammetry and Space Geodesy, integrated together, allowed a modern approach
to the representation of the archaeological area and the surrounding territory and to
record, manage and share all the acquired data in a single well-established reference
system. All this information represents a shared dataset useful in a multi-disciplinary
perspective for different applications and communities
Low-height aerial imagery and digital photogrammetrical processing for archaeological mapping
Full text linkIn the framework of the Joint Archaeological Mission of the Universities of Bologna and Lecce at the ancient town of Soknopaiou Nesos (Fayyum, Egypt) a wide-range of geomatic methodologies were experimented (GPS, total station surveys, low-height aerial and close-range photogrammetry, Visual Reality, high resolution satellite imagery, etc.). The surveys were conducted with the aim of recording metrical and non-metrical information inside a common reference system for the development of a GIS for the archaeological area.
The paper deals in particular with the acquisition and processing of low-height aerial imagery to provide very large-scale mapping of the area in support of archaeological researches. A remote controlled system, ad hoc developed for cultural heritage applications, permits to operate both semi-metric and non-metric cameras, lifted by balloon or kites with specific arrangements, in order to systematically take pictures over the study area.
The images acquired during the 2002 campaign by a non-metrical camera, calibrated by field calibration procedure, were processed within a Socet Set digital photogrammetric workstation: aero-triangulation, digital orthoimage generation and mosaicing were realized. The external orientation was established through kinematic GPS-derived ground control points, surveyed within the International Terrestrial Reference Frame ITRF2000; the same kinematic survey provided also a DTM for the entire site.
After a description of the overall approach to the survey of the site by the integration of different techniques, the paper describes the results obtained by this photogrammetric campaign, pointing out specifically the aspects concerning the non-standard image arrangement within the photogrammetric block, the problems arised by the geometrical structure of the buildings (e.g. the presence of very high mud-bricks walls in the temenos), and the use and comparison of DTMs derived from image-matching techniques or from GPS surveys
4-dimensional recording and visualization of urban archeological excavations
No full textThe new geomatic techniques and technologies for surveying an archeological excavation are not limited to obtaining more accurate data or more precisely geo-referenced positions on a map, as they can lead to new approaches and, indeed, raise the concept of different dimensions relating to the handled information. The techniques on offer are now fully 3D and, even more interestingly, can also permit to handle temporal information, that is, the evolution of operations over time. This allows scholars and technicians to build and maintain a wealth of vital knowledge documenting what happens during an excavation. This is further true when these are in urban areas, often known as “emergency excavations” from their distinctive logistics and timing constraints. The aim of this paper is to present, in a practical context, some of the many capabilities of 3D surveying performed through digital photogrammetry based on multi-view structure-from-motion approach in the field of urban emergency archeology. The information that can be derived from exploring three-dimensional models allows us to interact with realities that no longer exist, with the possibility not merely of recording their memory, but also of further studies and insights, even after a long period of time. In addition, the excavation itself is documented as it evolves, thus allowing the main phases of the process to be reconstructed retrospectively. The study case examined covers a small necropolis discovered in Rimini (Italy) in 2015. The results and the 3D final products can be managed through Geographic Information System (GIS) tools and, therefore, can easily be interfaced and integrated with other types of information on a different scale
INTEGRATED USE OF REMOTE SENSED DATA AND NUMERICAL CARTOGRAPHY FOR THE GENERATION OF 3D CITY MODELS
Full text link3D city models are becoming increasingly popular and important, because they constitute the base for all the visualization, planning, management operations regarding the urban infrastructure. These data are however not available in the majority of cities: in this paper, the possibility to use geospatial data of various kinds with the aim to generate 3D models in urban environment is investigated.
In 3D modelling works, the starting data are frequently the 3D point clouds, which are nowadays possible to collect by different sensors mounted on different platforms: LiDAR, imagery from satellite, airborne or unmanned aerial vehicles, mobile mapping systems that integrate several sensors. The processing of the acquired data and consequently the obtainability of models able to provide geometric accuracy and a good visual impact is limited by time, costs and logistic constraints.
Nowadays more and more innovative hardware and software solutions can offer to the municipalities and the public authorities the possibility to use available geospatial data, acquired for diverse aims, for the generation of 3D models of buildings and cities, characterized by different level of detail.
In the paper two cases of study are presented, both regarding surveys carried out in Emilia Romagna region, Italy, where 2D or 2.5D numerical maps are available. The first one is about the use of oblique aerial images realized by the Municipality for a systematic documentation of the built environment, the second concerns the use of LiDAR data acquired for other purposes; in the two tests, these data were used in conjunction with large scale numerical maps to produce 3D city models
Integration of Aerial Thermal Imagery, LiDAR Data and Ground Surveys for Surface Temperature Mapping in Urban Environments
Full text linkA single-band surface temperature retrieval method is proposed, aiming at achieving a better accuracy by exploiting the integration of aerial thermal images with LiDAR data and ground surveys. LiDAR data allow the generation of a high resolution digital surface model and a detailed modeling of the Sky-View Factor (SVF). Ground surveys of surface temperature and emissivity, instead, are used to estimate the atmospheric parameters involved in the model (through a bounded least square adjustment) and for a first assessment of the accuracy of the results. The RMS of the difference between the surface temperatures computed from the model and measured on the check sites ranges between 0.8 °C and 1.0 °C, depending on the algorithm used to calculate the SVF. Results are in general better than the ones obtained without considering SVF and prove the effectiveness of the integration of different data sources. The proposed approach has the advantage of avoiding the modeling of the atmosphere conditions, which is often difficult to achieve with the desired accuracy; on the other hand, it is highly dependent on the accuracy of the data measured on the ground
Georeferenced 3D model of the rock pinnacle "Campanile di Val Montanaia" from Structure from Motion
No full textWe produced a high-quality 3D model of a rocky pinnacle in the Dolomites (Italy), the "Campanile di Val Montanaia". The survey was performed by means of a lightweight Unmanned Aerial Vehicle (UAV) and by climbing the pinnacle to collect Ground Control Points (GCPs) coordinates. All data has been processed using Structure from Motion (SfM) technique. We share a georeferenced 3D mesh of the pinnacle aligned to ITRF2014 and delivered using projected coordinates UTM zone 33N (EPSG:32633). The dataset is associated with the following publication submitted to Remote Sensing: A Laboratory for the Integration of Geomatic and Geomechanical Data: The Rock Pinnacle "Campanile di Val Montanaia". Remote Sens. 2023, 15, 4854. https://doi.org/10.3390/rs1519485
Historical photogrammetry & terrestrial laser scanning for the 3D virtual reconstruction of destroyed structures: A case study in Italy
No full textThe current dramatic episodes of destruction of archaeological sites have again highlighted the problem of the safeguarding the threatened heritage and, if possible, recovering those damaged by all the armed conflicts of the past. The historical photogrammetry offers the possibility to recover a posteriori the geometrical and material properties of destroyed structures, reconstructing their 3D model to document, study and maintain their memory, until to support their real anastylosis. The presented work is about the 3D reconstruction of the civic tower of the little town of Sant'Alberto, near the city of Ravenna, Italy. The tower, as a symbol of resistance and pride of the town's population, was destroyed in December 1944 by German troops in retaliation, when they were forced to leave the area. A city committee has subsequently collected all the historical evidence concerning the tower, including a series of photographic images that can be used for the photogrammetric reconstruction; the images calibration and orientation have been solved using the geometric information derived by a terrestrial laser scanner survey realized in the area where the tower was originally located. Despite the scarcity and very poor quality of the available images, the conducted photogrammetric procedure has allowed a complete and qualitatively satisfying object reconstruction, also thanks to the use of geometric constraint tools offered by the chosen software. The integration between the obtained model of the old tower and the 3D TLS survey of the square made it possible to reconstruct the ancient situation of the area
Assessing Hazardous Spills Impact on Road Surface Performances by 3D High Resolution Surveying Techniques
No full textSurface texture of a road pavement is recognized as one of the most
relevant parameters in driving safety. Spillages on the highway can lead to dangerous
conditions for road users and cause damage to the road surface. Hazardous
substance spills caused by traffic accidents threaten the safety road and request a
specific clearance operation to reduce the risk of asphalt surface degradation. The
aim of this paper is to evaluate the effect of usual hazardous liquids spilled during
traffic accidents from vehicles on the asphalt properties and related safety parameters.
The experimental application is performed via digital photogrammetry. The
application of 3D geomatic techniques allows to calculate new texture indicators
through geometric and colorimetric information more accurate than traditional
survey techniques. The proposed approach can constitute a new useful investigation
method, in addition to traditional surveys, which are slower and less precise.
The texture reading by using three-dimensional analysis is an innovative way to
obtain and compare the traditional performance indicators used to measure friction
with new proposed indicators. In particular, the described experience evidences
the mechanical behaviour and the structural damage of asphalt samples related
to different exposure times treated with five hazardous liquids. Both traditional
and innovative techniques are carried out to evaluate roughness (British Pendulum
Number, BPN). The obtained results show how the various substances affect in
different way the samples asphalt surface
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