1,720,988 research outputs found
FROM MULTI-VIEW TO POINT CLOUD SEGMENTATION: THE CASE STUDY OF VILLA ROBERTI BRUGINE
Full text linkPoint cloud semantic segmentation is a key step for automatically deriving an informative building model from the 3D data reconstruction obtained by 3D surveying tools, such as laser scanners and photogrammetry. Such representation increases the richness of the information available of the represented building, leading to an at least rough interpretation of the scene, and, in particular, a discrimination between the different constitutive elements of the building. The growing interest in semantic building models recently motivated the development of several approaches aiming at obtaining an automatic semantic segmentation of a building point cloud. Such methods are usually either based on the direct segmentation of the point cloud, or on the segmentation of images of the building, then back-projecting the obtained segmentation on the point cloud. Similarly to the latter approach, this work assumes that a proper neural network is available in order to compute the semantic segmentation of building images, and it compares two different strategies for transferring such semantic information from the 2D images to the 3D point cloud. The results obtained in the case study of villa Roberti Brugine (Brugine, Padua, Italy) show that transferring the semantic information can be done quite effectively with the proposed, even when dealing with a certain amount of misclassified points. In particular, best results are obtained in our tests when determining a point class as the most popular classification of such point once projected on all the images where it is visible
Autonomous model helicopter for mobile mapping applications: first results
No full textIn the last years UAV (Unmanned Aerial Vehicle) systems are become very actractive for various commercial, industrial, public, scientific and military operations. The tasks include pipeline inspection, dam surveillance, photogrammetric survey, infrastructure maintenance, inspection of flooded areas, fire fighting, terrain monitoring, volcano observations and so on. The impressive flying capabilities provided by UAVs require a well trained pilot to be fully and effectively exploited; moreover the flight range of the piloted helicopter is limited to the line-of-sight or the skill of the pilot to detect and follow the orientation of the helicopter. Such issues have motivated the research and the design for autonomous system guidance which could both stabilize and also guide the helicopter precisely along a reference path. The constant growth of research programs and the technological progress in the field of navigation systems, as denoted by the production of more and more performing GPS/INS integrated units, allowed a strong cost reduction and payload miniaturization, making the design of low cost UAV platforms more feasible and actractive.
In this paper we present the preliminary results of the low-cost autonomous model helicopter we developed for mobile mapping applications. Assessment of system perfomance is based on the measurements achieved by surveying a set of targets well distributed on a calibration field. The development of this aerial mapping system has been also based on the results derived from a flight simulation software implemented for determining the best setup for the servos
Integrazione di tecniche di rilevamento per il controllo di stabilità di una struttura storica
No full textNegli anni recenti, la possibilità offerta dal laser scanner terrestre di acquisire grandi quantità di dati in tempi relativamente brevi, con un grado di precisione e dettaglio elevati, ha spinto l’interesse di topografi, ingegneri, architetti e archeologi a considerare il laser a scansione come uno strumento di rilevamento fondamentale per la modellazione 3D di oggetti e ambienti facenti parte del Patrimonio Culturale di una nazione. Prova di tale fenomeno è costituito dall’ampia varietà di oggetti che sino ad oggi sono stati sottoposti a scansione: dal piccolo pezzo di ceramica alla statua di marmo, dall’edificio storico ad un intero sito archeologico. D’altra parte, nel panorama dei possibili impieghi del laser a scansione, la sua applicazione per il controllo di stabilità di una struttura o edificio di interesse storico appare tutt’ora un campo di ricerca poco indagato. Al fine di approfondire questa tematica di ricerca, è stato attivato un progetto triennale volto a verificare la possibilità di utilizzare in modo integrato una molteplicità di tecniche di rilevamento per il controllo della stabilità di una struttura storica caratterizzata da una geometria complessa. In particolare, tale progetto prevede di utilizzare strumentazione laser scanner terrestre, stazione totale, flessimetri, fotogrammetria e termografia per effettuare una serie di rilievi a cadenza semestrale del Teatro Anatomico dell’Università di Padova. Lo scopo del progetto in questione è quello di verificare la stabilità nel tempo di questo tipo di struttura, considerando in particolare gli effetti del decadimento organico delle parti in legno.
In questa nota vengono quindi presentati i risultati ottenuti finora, ponendo particolare attenzione ai problemi e difficoltà insorte nel rilievo laser scanner e modellazione 3D di una struttura di interesse storico e culturale caratterizzata da una geometria inusuale e alquanto complessa
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Development and Initial Assessment of a Low Cost Mobile Mapping System
No full textMobile mapping system have been used in a wide range of applications during the last decades, most of the times with the goal of quickly and quite reliably acquiring georeferenced spatial information of relatively large areas of interest. Indeed, such kind of systems are often preferred to static surveying techniques when dealing with relatively large areas, where static approaches would require very long surveys. Terrestrial mobile mapping systems are composed by a positioning and mapping system, which is typically mounted on a terrestrial vehicle, such as a car. The use of such systems can be limited by (i) possible restrictions on the area of interest, which might be not well suited for the use of such vehicles, and (ii) by their quite high costs, mostly related to the use of expensive sensors in order to ensure high accuracy and reliability of the acquired geospatial information. Despite preserving the quality of the produced information imposes quite stringent restrictions on the used sensors, and consequently on their costs, nowadays the recent technological improvements allowed the development of a number of low cost sensors, which can be used in a mapping system instead of their expensive counterparts. In accordance with such consideration, this paper aims at presenting the development of mobile mapping system with low cost sensors, and an initial evaluation of the performance achievable with such system: indeed, the use of low cost sensors typically reduce the quality of obtained results, or restricts the conditions of usability. To be more specific, this paper presents two versions, one based on stereo vision and the other on mobile laser scanning, of a low cost mobile mapping system recently realized by the University of Padua
Variations on the Author
Full text link“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
- …
