1,720,988 research outputs found
Innovative Use and Integration of Remote Sensed Geospatial Data for 3D City Modeling and GIS Urban Applications
Full text linkModern remote sensing instruments, mounted on a modern aerial platform and assisted through the use of automated procedures are now capable of acquiring data over a vast area in a short timeframe. Thanks to innovative processing methods and algorithms it is then possible to rapidly deliver results with a high detail and accuracy. The discussed thesis provides a detailed overview, through different case studies and examples, on the evolving complete pipeline required to survey, process, store, integrate, analyze and deliver data in the form of a 3D city model and GIS in the urban environment. A comprehensive 3D city model is, in fact, the necessary multi-disciplinary backbone for the ubiquitous sensors of a Smart City
Tecniche per l'estrazione automatica di edifici da nuvole di punti con software proprietari ed open source
No full textLe tecniche e le procedure di estrazione automatica e semi-automatica di informazioni a partire da dati telerilevati sono in continua evoluzione, in seguito ad un grande interesse scientifico e commerciale. Oggetto della presente sperimentazione sono diversi algoritmi, implementati in altrettanti software proprietari ed open source, in grado di rilevare le geometrie di edifici all'interno di nuvole di punti. Tali dati possono essere acquisiti da strumentazione aerea LiDAR o processati per via fotogrammetrica. I software confrontati in questo lavoro prevedono differenti flussi di lavoro in quanto strutturati per rispondere a diverse esigenze nell'ambito dell’elaborazione di dati geo-spaziali. Tale confronto per l'estrazione e la classificazione di informazioni tematiche si è svolto con GRASS GIS, ENVI LiDAR e LAStools. Le procedure sono state testate con un dataset comune ed i risultati sono analizzati come cartografia numerica in ambiente GIS. Ulteriori considerazioni vengono effettuate per valutare le diverse funzionalità dei software, confrontandone le prestazioni e le caratteristiche peculiari
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
An Object-Oriented Approach to the Classification of Roofing Materials Using Very High-Resolution Satellite Stereo-Pairs
Full text linkThe availability of multispectral images, with both high spatial and spectral resolution, makes it possible to obtain valuable information about complex urban environment, reducing the need for more expensive surveying techniques. Here, a methodology is tested for the semi-automatic extraction of buildings and the mapping of the main roofing materials over a urban area of approximately 100 km2, including the entire city of Bologna (Italy). The methodology follows an object-oriented approach and exploits a limited number of training samples. After a validation based on field inspections and close-range photos acquired by a drone, the final map achieved an overall accuracy of 94% (producer accuracy 79%) regarding the building extraction and of 91% for the classification of the roofing materials. The proposed approach proved to be flexible enough to catch the strong variability of the urban texture in different districts and can be easily reproducible in other contexts, as only satellite imagery is required for the mapping
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
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Technical Challenges for Multi-Temporal and Multi-Sensor Image Processing Surveyed by UAV for Mapping and Monitoring in Precision Agriculture
Full text linkPrecision 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
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