SELF-ASSEMBLED ROV AND PHOTOGRAMMETRIC SURVEYS WITH LOW COST TECHNIQUES

In last years, ROVs, have been employed to explore underwater environments and have played an important role for documentation and surveys in different fields of scientific application. In 2017, the Laboratorio di Fotogrammetria of Iuav University of Venice has decided to buy an OpenRov, a low cost ROV that could be assembled by ourselves to add some external components for our necessities, to document archaeological sites.<br> The paper is related to the photogrammetric survey for the documentation of underwater environments and to the comparison between different solutions applied on a case studio, five marble columns on a sandy bottom at 5 meters deep. On the lateral sides of the ROV, we have applied two GoPro Hero4 Session, which have documented the items both with a series of images and with a video. The geometric accuracy of the obtained 3D model has been evaluated through comparison with a photogrammetric model realized with a professional reflex camera, Nikon D610. Some targets have been topographically surveyed with a trilateration and have been used to connected in the same reference system the different models, allowing the comparisons of the point clouds. Remote Operating Vehicles offer not only safety for their operators, but are also a relatively low cost alternative. The employment of a low-cost vehicle adapted to the necessities of surveys support a request for safer, cheaper and efficient methods for exploring underwater environments

Caratterizzazione tipologica dei rapporti tra fenomeni di desertificazione ed acque superficiali e sotterranee, osservati e studiati in Sardegna

This study has been carried out within a broader research project, RIADE, concerned with the characterization of the types of relationships existing between desertification processes and surfaceand groundwater observed and investigated in Objective 1 regions. The underlying assumption is that the deteriorating quality and diminishing quantity of a region’s water resources impact negatively on the development of all living things and on human organization, and thus represent a basic indicator of desertification, intended in its broadest sense as the degradation of bioproductive land. By re-processing the scientific results obtained for Sardinia during this project, we have developed a reference framework for the systematic representation of the types found, qualitatitive/quantitative natural or anthropogenic degradation phenomena/processes of water resources in Sardinia. Two distinct criteria have been adopted for the typological categorization of the deteriorating quality and diminishing quantity of water, both divorced from the environmental and regional context in which they occur.The first criterion is based on an analysis of water quantity and quality and on the “pollutant type”, along the lines suggested by the Italian Research Council’s National Group for Hydrogeological Disaster Protection (GNDCI); the second criterion uses the DPSIR model adopted by the European Environmental Agency (EEA), which defines five indicator categories for the state and evolution of the environmen

The bust o Francesco II Gonzaga: from digital documentation to 3d printing

Geomatics technics and methods are now able to provide a great contribution to the Cultural Heritage (CH) processes, being adaptable to different purposes: management, diagnosis, restoration, protection, study and research, communication, formation and fruition of the Cultural Heritage. This experimentation was done with an eye to encouraging and promoting the development of principles and good practices for recording, documentation and information management of cultural heritage This research focuses on the documentation path of a cultural asset, in particular a Renaissance statue, aimed to achieve a three dimensional model useful for many digital applications and for solid reproduction. The digital copy can be used in many contexts and represents an efficient tool to preserve and promote CH. It can be included in virtual museum archives and catalogues, shared on network with cultural operators and users, and it permits the contextualization of the asset in its artistic and historical background. Moreover, the possibility to obtain a hard copy, reproduced through 3D printing, allows to reach new opportunities of interaction with CH. In this article, two techniques for the digitization of the terracotta bust of Francesco II Gonzaga, in the City Museum of Mantua, are described: the triangulation scanner and dense image matching photogrammetry. As well as the description of the acquisition and the elaborations, other aspects are taken into account: the characteristics of the object, the place for the acquisition, the ultimate goal and the economic availability. There are also highlighted the optimization pipeline to get the correct three-dimensional models and a 3D printed copy. A separate section discusses the comparison of the realized model to identify the positive and negative aspects of each adopted application

Underwater photogrammetry and 3D reconstruction of marble cargos shipwreck

Nowadays archaeological and architectural surveys are based on the acquisition and processing of point clouds, allowing a high metric precision, essential prerequisite for a good documentation. Digital image processing and laser scanner have changed the archaeological survey campaign, from manual and direct survey to a digital one and, actually, multi-image photogrammetry is a good solution for the underwater archaeology. This technical documentation cannot operate alone, but it has to be supported by a topographical survey to georeference all the finds in the same reference system. In the last years the Ca' Foscari and IUAV University of Venice are conducting a research on integrated survey techniques to support underwater metric documentation. The paper will explain all the phases regarding the survey's design, images acquisition, topographic measure and the data processing of two Roman shipwrecks in south Sicily. The cargos of the shipwrecks are composed by huge marble blocks, but they are different for morphological characteristic of the sites, for the depth and for their distribution on the seabed. Photogrammetrical and topographical surveys were organized in two distinct methods, especially for the second one, due to the depth that have allowed an experimentation of GPS RTK's measurements on one shipwreck. Moreover, this kind of three-dimensional documentation is useful for educational and dissemination aspect, for the ease of understanding by wide public

DIGITAL SURVEY TECHNIQUES FOR THE DOCUMENTATION OF WOODEN SHIPWRECKS

Nowadays, researchers widely employ the acquisition of point clouds as one of the principal type of documentation for cultural heritage. In this paper, different digital survey techniques are employed to document a wooden ancient shipwreck, a particular and difficult kind of archaeological finding due to its material characteristics. The instability of wood and the high costs of restoration do not always offer the opportunity of recovering and showing the hull to researchers and public and three-dimensional surveys are fundamental to document the original conditions of the wood. The precarious conditions of this material in contact with air could modify the structure and the size of the boat, requiring a fast and accurate recording technique. The collaboration between Ca' Foscari University and the Laboratory of Photogrammetry of Iuav University of Venice has given the possibility to demonstrate the utility of these technology. We have surveyed a sewn boat of Roman age through multi-image photogrammetry and laser scanner. Point clouds were compared and a residual analysis was done, to verify the characteristics and the opportunity of the two techniques, both of them have allowed obtaining a very precise documentation from a metrical point of view

Photogrammetry in maritime and underwater archaeology: two marble wrecks from Sicily

Underwater survey, compared to land archaeology, needs some specific techniques, because the application of some active 3D sensor, such as laser scanner, is obviously impossible. The necessity to produce three-dimensional survey, offering the same accuracy of classical terrestrial laserscanning or photogrammetric methods, combined with the request of low costs and rapid solutions, led the researchers to test and apply oftentimes image-based techniques.In the last two years the Ca' Foscari University and University IUAV of Venice are conducting a research on the application of integrated techniques to support underwater metric documentation, comparing them to the manual traditional one. The gained experience (and confirmed by other recently published papers) shows that the actual multi-image digital photogrammetry is a good solution for the underwater archaeology. This approach is useful both from a metric and from a recording point of view, because it achieves high quality results, such as accurate 3D models or 2D representations, offering a complete documentation of underwater sites.But photogrammetry has to be supported by a topographical survey (to acquire ground control points - GCP) to georeference all the finds in the same reference system. This paper presents the integrated survey of two roman shipwrecks, approaching differently in the GCP's acquisition just for the different morphological characteristic of the sites. The wrecks' cargos are huge marble blocks, presenting differences in quantities, layout and depths. Those characteristics determine the choice of the topographic survey.The results of the survey are two 3D polygonal textured models of the sites, which can be easily used for different analyses and reconstructive hypothesis, opening new possibilities of documentation with both specialists and the wider public. Furthermore, 3D models are the geometric base for 2D orthophoto and cross section extraction. The paper will illustrate all the phases regarding the survey's design, acquisition and realization and the data processing to obtain 2D and 3D final representation

Rilievo e confronto dell'arco dei Gavi e della sua maquette lignea: tecniche 3D per l'anastilosi virtuale

La moderna Geomatica, appoggiata da una strumentazione sempre più avanzata, hardware e software, offre nel settore dei beni Culturali, opportunità di nuove e interessanti applicazioni. Queste applicazioni non sono solo legate alla conservazione, al recupero, al restauro e alla riproduzione-prototipazione del bene, ma anche alla progettazione digitale e virtuale di eventuali interventi conservativi o strutturali di monumenti, non più esistenti o ricostruiti, e alla catalogazione e allo studio di manufatti di varie dimensioni. La possibilità di ottenere un dato digitale tridimensionale, un modello, così vicino alla realtà, ma anche svincolato dai suoi rigidi sistemi, ci permette di realizzare operazioni e studi altrimenti difficili, troppo macchinosi se non a volte impossibili. Nel caso in esame, il modello ligneo ha una funzione ben specifica e importante: è il database per la ricostruzione del monumento architettonico, è la memoria storica tridimensionale di un'architettura che è stata smontata, aiuterà l'architetto alla ricostruzione e non anticiperà la realtà ma la farà tornare. Gli oggetti presi in esame in questa tesi sono l'arco dei Gavi, monumento architettonico del primo secolo dopo Cristo, demolito nel 1805 dall'esercito napoleonico per facilitare il passaggio delle truppe, e il suo modello ligneo, successivo rispetto alla demolizione, realizzato nel 1813, di fondamentale importanza per la ricostruzione del monumento. La tecnologia attuale nel campo del rilievo ci permette di rilevare, analizzare e confrontare due oggetti tanto diversi per dimensioni e genesi che invece dovrebbero essere la stessa rappresentazione dell'Arco dei Gavi. L'obiettivo è quindi ottenere due modelli numerici confrontabili ed analizzabili, due modelli che ci permettano di trovare differenze, uguaglianze e discontinuità nella forma e nei pezzi che li compongono o punti di contatto e similitudine. Altro aspetto è l’individuazione di eventuali pezzi fuori opera, di alcuni è nota l'esistenza, e, dopo averli rilevati e modellati digitalmente, riposizionarli in ambiente virtuale nella loro ipotetica e antica posizione

Digitization of maps belonging to cultural heritage

maps are an essential documentary heritage for the knowledge of ter-ritory. Digitization, in the case of old maps, cannot be a simple high-resolution two-dimensional scan, but it has to detect the geometry of the supporting material. This work describes part of an on-going project, developed by the Laboratory of Photo-grammetry of IUAV University, concerning the study of different methodologies and tools for the 3D digitization of old maps. In particular, high-resolution cameras, combined with a mechanical positioning system and appropriate software for the rigorous construction of “mosaics”, will be explored as a potential means of replacing the expensive large format flatbed scanners. The research aims to digitally record the shape of maps, not only consid-ering their semantic content (printed image), but also their three-dimensional surfaces, and their subjection to time and deformations. Through the development of new algorithms, procedures and mechanical properties, it will be possible to obtain a rigorous three-dimensional geometric memory of the original cartographic heritage

Surveying and Comparing the Arco Dei Gavi and its Historical Wooden Maquette

Actually geometrics’ science offers new opportunities and interesting applications in the field of Cultural Heritage. These applications are strictly related to preservation, restoration but even to cataloging and reproducing a monument that no longer has its original integrity.  The possibility of obtaining 3D data, of such a model close to reality, enables us to realize studies that sometimes are too complex or impossible. The paper will describe the study of a monumental arch, the Arco dei Gavi, built in Verona during the I sec. A.C., that was destroyed in 1805 by the Napoleonic army, and its wooden model that was realized in 1813 and it has a very important role concerning the monument’s reconstruction. The purpose is to realize two threedimensional models which can be comparable to each other, two models with recognizable differences, similarities and discontinuities about shapes and single elements that compose the monument. It should also be noted that some original parts of the monument have not been relocated but are badly preserved in a museum: the 3D digital model helps to identify these parts in their original location. The main steps of the work can be summarized in: collecting the historical documentation of Arco dei Gavi and its representations; identifying proper instruments (laser scanning and photogrammetric hardware and software); surveying the Arch and its wooden model; identifying a unique and shared reference system; comparing both digital models related to the same scale; choosing a three-dimensional representation to emphasize the results; reallocation of outstanding pieces (virtual anastylosis)