28,342 research outputs found
Tini
No full textVoce biografica: si ricostruisce il percorso biografico e l'attività dei Tini, una delle principali famiglie di editori, tipografi e librai attivi a Milano fra la seconda metà del Cinquecento e i primi decenni del Seicento
A Comparative Study of the Applied Methods for Estimating Deflection of the Vertical in Terrestrial Geodetic Measurements
No full textThis paper compares three different methods capable of estimating the deflection of the vertical (DoV): one is based on the joint use of high precision spirit leveling and Global Navigation Satellite Systems (GNSS), a second uses astro-geodetic measurements and the third gravimetric geoid models. The working data sets refer to the geodetic International Terrestrial Reference Frame (ITRF) co-location sites of Medicina (Northern, Italy) and Noto (Sicily), these latter being excellent test beds for our investigations. The measurements were planned and realized to estimate the DoV with a level of precision comparable to the angular accuracy achievable in high precision network measured by modern high-end total stations. The three methods are in excellent agreement, with an operational supremacy of the astro-geodetic method, being faster and more precise than the others. The method that combines leveling and GNSS has slightly larger standard deviations; although well within the 1 arcsec level, which was assumed as threshold. Finally, the geoid model based method, whose 2.5 arcsec standard deviations exceed this threshold, is also statistically consistent with the others and should be used to determine the DoV components where local ad hoc measurements are lacking
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
EXPERIMENTAL TEST ON CONTROL POINTS MATERIALIZATION FOR THE STUDY OF VERTICAL MOVEMENTS OF SOIL AND ITS INTERACTIONS WITH GROUND WATER CONTENTS
No full textIn the study of soil vertical movements, one of the techniques most commonly used is the spirit levelling, now flanked by satellite SAR interferometry and by the analysis of time series acquired through permanent GNSS stations.
The reliability of control points monuments varies depending both on the geological context and on the structure being representative of the investigated phenomenon. Often due to the high number of desired points or to the need of maintaining a specific areal distribution, they are fixed on existing structures (as in the common case of spirit levelling networks). This aspect is even more evident in the case of SAR interferometric analysis, where the permanent scatterers are identified on the basis of consistency in the radar response, but the points display movements measured by structures with different foundations at different depths.
Starting from repeated precision levelling measurements, we verified which is the order of magnitude of movements of control points characterized by shallow foundations in cohesive soils, observing their behaviours at different depths, under simple and very common conditions such as the presence of periods of drought or rainfall. The results point-out movements in the order of 3–7 mm in the first meter of depth occurred in a week, during the transition between the period of summer drought and the first rains
Utilizzo di un sistema non convenzionale di fotogrammetria aerea per la produzione di ortofoto a grande scala in ambito archeologico
No full textLa ricchezza descrittiva e il contenuto geometrico rigoroso hanno reso l’ortofoto uno dei prodotti fotogrammetrici di più ampio interesse e diffusione nell’ambito dei beni culturali ed in particolare dell’Archeologia.
Il lavoro presentato riguarda un esempio di produzione di ortofoto su un’area archeologica, con un livello di precisione e dettaglio sufficienti ad una rappresentazione a grandissima scala, tramite l’utilizzo di immagini non metriche acquisite da bassa quota con un sistema aereo non convenzionale.
Il sistema di acquisizione è basato sull’utilizzo di palloni aerostatici guidati manualmente da terra, a cui viene fissata la camera semi-metrica il cui assetto è gestito in remoto mediante un radiocontrollo. In particolare per la sperimentazione sono stati utilizzati fotogrammi acquisiti durante la campagna di scavi del 2002 condotta nell’ambito della missione archeologica congiunta delle Università di Bologna e Lecce, nel sito di Soknopaiou Nesos (Fayyum, Egitto). Nel corso della stessa campagna è stato eseguito un rilievo GPS cinematico per la produzione di un DTM dell’area di scavo e per l’individuazione di punti di appoggio naturali e pre-segnalizzati.
L’elaborazione fotogrammetrica, eseguita con la stazione digitale SOCET SET v 5.1 (BAE Systems), si è articolata nelle fasi di triangolazione aerea per l’orientamento esterno, nell’estrazione di un DSM di elevata densità e nella produzione di un ortomosaico. Il livello di precisione e dettaglio ottenuto, consente di ritenere il prodotto raster finale compatibile con una scala nominale di 1:1000.
Nel presente contributo vengono presentati i risultati ottenuti con particolare riferimento alle difficoltà di elaborazione fotogrammetrica dovute da una parte alla geometria non convenzionale delle prese aeree e dall’altra alla particolare morfologia dell’area in esame, caratterizzata da ampie zone sabbiose a radiometria uniforme e da bruschi dislivelli in corrispondenza delle strutture
Technical Challenges for Multi-Temporal and Multi-Sensor Image Processing Surveyed by UAV for Mapping and Monitoring in Precision Agriculture
No full textPrecision Agriculture (PA) is an approach to maximizing crop productivity in a sustainable manner. PA requires up-to-date, accurate and georeferenced information on crops, which can be collected from different sensors from ground, aerial or satellite platforms. The use of optical and thermal sensors from Unmanned Aerial Vehicle (UAV) platform is an emerging solution for mapping and monitoring in PA, yet many technological challenges are still open. This technical note discusses the choice of UAV type and its scientific payload for surveying a sample area of 5 hectares, as well as the procedures for replicating the study on a larger scale. This case study is an ideal opportunity to test the best practices to combine the requirements of PA surveys with the limitations imposed by local UAV regulations. In the field area, to follow crop development at various stages, nine flights over a period of four months were planned and executed. The usage of ground control points for optimal georeferencing and accurate alignment of maps created by multi-temporal processing is analyzed. Output maps are produced in both visible and thermal bands, after appropriate strip alignment, mosaicking, sensor calibration, and processing with Structure from Motion techniques. The discussion of strategies, checklists, workflow, and processing is backed by data from more than 5000 optical and radiometric thermal images taken during five hours of flight time in nine flights throughout the crop season. The geomatics challenges of a georeferenced survey for PA using UAVs are the key focus of this technical note. Accurate maps derived from these multi-temporal and multi-sensor surveys feed Geographic Information Systems (GIS) and Decision Support Systems (DSS) to benefit PA in a multidisciplinary approach
Low-height aerial imagery and digital photogrammetrical processing for archaeological mapping
No full textIn 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
Comparison of two technologies in 3D surveying of real estate assets and cultural heritage
No full textAccurate three-dimensional (3D) data from indoor spaces holds significant importance in various fields like real estate management, industrial archaeology and Cultural Heritage. Villa Maraffa complex, located near Ravenna (Italy), served as a case study for employing and comparing advanced technology and sensors in surveying these contexts. To acquire data, the sensors used were Matterport Pro 2 and Leica RTC360. The first one, mainly developed for real estate surveys, has been chosen because of the efficiency and cost-effectiveness in generating point clouds, although with lower precision compared to the Leica RTC360 Laser Scanner, the other sensor employed in this study. The focus of the paper is on assessing the point cloud's quality, with an analysis of the Matterport data, including global and specific evaluations. Potential issues like incomplete data and misalignment are identified by comparing coordinates from the Leica scanner. The results are examined to find an optimal solution for a prompt, precise, and well-timed survey, enabling a complete digital reconstruction of the object
High-precision topographical methodology for determining height differences when crossing impassable areas
No full textWith the arrival on the market of high-precision topographic total stations, professionals today, using appropriate methodologies, can determine altimetric connections to an accuracy that is almost comparable to those obtainable using high-precision geometric levelling. This aspect is of particular interest when it is not possible to proceed with classical geometric levelling operations due to logistical or other reasons: for instance, where levelling lines need to cross impassable areas such as streams, soft soils or canyons. Currently, height differences between two points separated by an impassable area are mainly measured using optical-mechanical levels by procedures that present a number of difficulties. This work presents the results achieved through several trials conducted on the use of high precision trigonometric levelling for measurement of height difference between benchmarks at opposite sides of streams. In particular, it describes the project where simultaneous and reciprocal measures were taken using two high-precision robotic total stations. © 2018 Elsevier Lt
Geodetic measurements to control a large research infrastructure. The Virgo detector at the European Gravitational Observatory
No full textThe Advanced Virgo (AdV) detector is a 3 km long arms Michelson interferometer for gravitational waves detection. The management of a complex and large research infrastructure requires high-precision geodetic surveying for positioning and rearrangement of instruments.
This paper describes the establishment of Virgo Reference System (VRS) consisting in a wide-scale high precision geodetic network based on GPS and Total Station measurements, that support the positioning and the alignment of the different elements forming the interferometer. Ground settlement monitoring is strictly required to verify and adapt the interferometer vertical alignment in presence of a steady subsidence process due to infrastructures overloads. The paper describes also the monitoring activity conducted over the years by means of periodic high precision levelling, that was compared with the results with those obtained using differential interferometry based on satellite Synthetic Aperture Radar (SAR) data
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