102,202 research outputs found
From low-cost to high-quality: a foss4G framework of uav photogrammetric processing for geospatial data extraction
No full textUno degli argomenti delle scienze della Terra più incoraggiati dalla rivoluzione dei Big Data è legato alle tecnologie e alle tecniche di Osservazione della Terra. I recenti sviluppi nel Telerilevamento e nelle tecniche di calcolo hanno innescato una crescita esplosiva di questi dati. Nuovi sistemi satellitari, aerei e terrestri caratterizzati da un'alta risoluzione spaziale, temporale e radiometrica sono in continua evoluzione, e le grandi masse di dati confluiscono così nei Big Geospatial Data, orientati ad aiutare in modo intersettoriale molteplici industrie e il mondo accademico con un nuovo approccio. Mentre questi dati contengono importanti informazioni, sono allo stesso tempo eterogenei, multi-sorgente, multi-temporali, multi-scala, altamente dimensionali, altamente complessi e non strutturati, e sono emerse difficoltà nell’archiviazione dei dati, nell'elaborazione, nella convalida dei risultati e anche nella loro analisi. Dal punto di vista dell'hardware, l'introduzione di computer e sensori a basso costo ha ampliato il potenziale di acquisizione dei dati. Dal punto di vista software, l'adozione di piattaforme sempre più performanti e specializzate Free and Open Source Software for Geospatial (FOSS4G) sta rivoluzionando il modo di lavorare, guidando uno orientamento verso la scienza aperta, la condivisione delle conoscenze, l'accessibilità e la riproducibilità. È evidente che questi rinnovamenti richiedono l'implementazione su misura di frame della catena del valore di alto livello. Date le numerose sfide in questo campo in cui la comunità scientifica sembra essere rigorosamente impegnata, una quota crescente di interesse viene posta nel progresso degli Unmanned Aerial Vehicles (UAV), Sistemi Aeromobili a Pilotaggio Remoto. Le immagini aeree catturate dagli UAV stanno giocando un ruolo sempre più importante in varie industrie grazie alla loro efficienza, flessibilità, trasversalità e versatilità d'uso. Tuttavia, le tecnologie UAV e le tecniche basate su di esse sono ancora in fase di sviluppo e diversi problemi devono essere risolti. Tra i molti già discussi dalla comunità scientifica, è stato evidenziato che l'interpretazione e l'analisi manuale dei dati integrati non sono più adeguate, motivo per cui sono necessari sofisticati metodi di analisi automatica per rendere il processo efficiente ed efficace. Questa tesi cerca quindi di sviluppare un framework FOSS4G per il pre-processing e post-processing di prodotti fotogrammetrici, utile per l'estrazione automatica di informazioni quasi in tempo reale, applicati a dati ad alta risoluzione, multi-scala, multi-temporali e multi-sensore per il monitoraggio ambientale e l'ispezione tecnica degli edifici. Si percorre quindi la struttura con-centrandosi sulle piattaforme UAV attualmente a basso costo dotate di sensori economici, sulla configurazione e ottimizzazione delle attività in campo di acquisizione e preelaborazione al fine di ridurre sia i costi accessori che il sovraccarico delle opera-zioni e, allo stesso tempo, testando diverse metodologie per estrarre informazioni da dati caratterizzati da diverse risoluzioni spettrali e spaziali. Vengono proposte le procedure di validazione dei prodotti ottenibili dalla catena di processo per individuare la loro collocazione tra le diverse alternative più consuete dei dati di Osservazione della Terra. Come risultato, questa tesi dà forma ad una procedura ripetibile e riproducibile, testa e convalida i prodotti che possono essere restituiti, e propone metodi innovativi di analisi basati sul trattamento di immagini e sui punti. Il lavoro ha quindi cercato di affrontare alcune delle limitazioni riguardanti la raccolta e la preelaborazione delle informazioni in modo tempestivo ed economico, e la mancanza di un quadro accreditato per l'elaborazione dei dati fotogrammetrici che possa essere considerato riproducibile, ripetibile e ampiamente accessibile nel contesto della democratizzazione della Data Science. Viene così teorizzata e validata la collocazione strategica dei pro-dotti basati su UAV tra quelli di tecnologie più consolidate. Infine, il lavoro propone una risposta alla complessità nel trattamento e gestione di dati ad alta risoluzione spettrale e spaziale, come le grandi quantità di dati nelle applicazioni in tempo reale, per estrarre informazioni mirate per risolvere problemi specifici. Quindi, il processo di strutturazione del presente lavoro di ricerca passa attraverso quattro fasi principali: (1) maturazione concettuale delle piattaforme e dei sensori e la loro integrazione, (2) strutturazione di un quadro di elaborazione FOSS4G, (3) preelaborazione geometrica e radiometrica dei dataset acquisiti, e (4) analisi ed estrazione di informazioni basate su immagini e punti. In vista di tutto ciò, i principali contributi di questa tesi alla ricerca sono stati quelli di organizzare un quadro completo open-source che andasse dal-la strategia di acquisizione e la fase di georeferenziazione, passando per la preelaborazione geometrica e radiometrica, sino all'elaborazione dell'output e l'analisi. Allo stesso tempo, anche quella di applicare metodologie aperte per l'analisi basata sui pixel e sui punti derivati da processamenti fotogrammetrici ottenibili da indagini multi-scala, multi-temporali e multi-sensore, e di raggiungere questi obiettivi con alta qualità ma utilizzando tecnologie e tecniche a basso costo per aumentarne l'accessibilità. Importanti implicazioni tecniche e tecnologiche, basate sull'automazione delle opera-zioni, risultano dall'adozione del quadro proposto.One of the topics of Earth sciences most encouraged by the Big Data revolution is related to Earth Observation technologies and techniques. Recent developments in Remote Sensing and computing techniques have triggered an explosive growth of this data. New satellite, airborne, and terrestrial systems characterised by high spatial, temporal, and radiometric resolution are continuously evolving, and the large masses of data thus flow into Big Geospatial Data, geared to cross-sectorally help multiple industries and academia with a new approach. Whereas this data contains powerful information, it is at the same time heterogeneous, multi-source, multi-temporal, multi-scale, highly dimensional, highly complex, and unstructured, and difficulties emerged in data storage, processing, validation of results and even analysis. From the hardware perspective, the introduction of low-cost computers and sensors has expanded the potential for data acquisition. On the software side, the adoption of increasingly performant and specialised Free and Open-Source Software for Geospatial (FOSS4G) platforms is revolutionising the way of working, driving a shift towards open science, knowledge sharing, accessibility and reproducibility. It is evident that these renovations require the tailored implementation of high-level value chain frameworks. Given the numerous challenges in this field in which the scientific community appears to be rigorously engaged, an increasing share of interest is being placed in the progress of Unmanned Aerial Vehicles (UAVs). Aerial imagery captured by UAVs is playing an increasingly important role in various industries due to its efficiency, flexibility, transversality, and versatility of use. However, UAV technologies and techniques based on them are still under development and several problems need to be solved. Among the many already discussed by the scientific community, it was pointed out that manual interpretation and analysis of integrated data is no longer adequate, which is why sophisticated automatic analysis methods are needed to make the process efficient and effective. This dissertation thus seeks to develop a FOSS4G framework for pre-processing and post-processing of photogrammetric products, useful for the automatic extraction of near real-time information applied to high-resolution, multiscale, multi-temporal, and multi-sensor data for environmental monitoring and technical inspection of buildings. Therefore, it goes through the structure focusing on the currently low-cost UAV platforms equipped with economic sensors, on the configuration and optimisation of the field acquisition and pre-processing activities in order to reduce both the ancillary costs and the effort of operations and, at the same time, testing different methodologies to extract information from data characterised by different spectral and spatial resolutions. The validation procedures of the products obtainable from the process chain are proposed to identify their placement among the different more usual alternatives of Earth Observation data. As a result, this thesis reconstructs a repeatable and reproducible procedure, tests and validates the products that can be rendered, and proposes innovative image-based and point-based analysis methods. The work, therefore, sought to address some of the limitations regarding the collection and pre-processing of information in a timely and cost-effective manner, and the lack of an accredited framework for processing photogrammetric data that could be considered reproducible, repeatable, and widely accessible in the context of the Data Science democratisation. The strategic placement of UAV-based products among those of more established technologies is thus theorised and validated. Finally, the work proposes a response to the complexity of dealing with high spectral and spatial resolution data, such as large amounts of data in real-time applications, to extract targeted information to solve specific issues. Hence, the process of structuring the current research work goes through four main stages: (1) conceptual maturation of the platforms and sensors and their integration, (2) structuring of a FOSS4G processing framework, (3) geometric and radiometric pre-processing of the acquired datasets, and (4) image-based and point-based analysis and information extraction. In view of all this, the main contributions of this thesis were to organize a comprehensive open-source framework ranging from acquisition strategy and georeferencing step, geometric and radiometric pre-processing, output processing, and analysis. At the same time, to apply open methodologies for pixel-based and point-based analysis of producible photogrammetric results for multi-scale, multi-temporal, and multi-sensor surveys, and achieve these targets with high quality but using low-cost technologies and techniques to increase their accessibility. Important technical and technological implications, based on the automation of operations, result from the adoption of the proposed framework
Comparison between empirical and physically based models of atmospheric correction
No full textA number of methods have been proposed for the atmospheric correction of the multispectral satellite images, based on either atmosphere modelling or images themselves. Full radiative transfer models require a lot of ancillary information about the atmospheric conditions at the acquisition time. Whereas, image based methods cannot account for all the involved phenomena. Therefore, the aim of this paper is the comparison of different atmospheric correction methods for multispectral satellite images. The experimentation was carried out on a study area located in the catchment area of Yialias river, 20 km South of Nicosia, the Cyprus capital. The following models were tested, both empirical and physically based: Dark object subtraction, QUAC, Empirical line, 6SV, and FLAASH. They were applied on a Landsat 8 multispectral image. The spectral signatures of ten different land cover types were measured during a field campaign in 2013 and 15 samples were collected for laboratory measurements in a second campaign in 2014. GER 1500 spectroradiometer was used; this instrument can record electromagnetic radiation from 350 up to 1050 nm, includes 512 different channels and each channel covers about 1.5 nm. The spectral signatures measured were used to simulate the reflectance values for the multispectral sensor bands by applying relative spectral response filters. These data were considered as ground truth to assess the accuracy of the different image correction models. Results do not allow to establish which method is the most accurate. The physics-based methods describe better the shape of the signatures, whereas the image-based models perform better regarding the overall albedo
Influence of Spatial Resolution for Vegetation Indices’ Extraction Using Visible Bands from Unmanned Aerial Vehicles’ Orthomosaics Datasets
No full textThe consolidation of unmanned aerial vehicle (UAV) photogrammetric techniques for campaigns with high and medium observation scales has triggered the development of new application areas. Most of these vehicles are equipped with common visible-band sensors capable of mapping areas of interest at various spatial resolutions. It is often necessary to identify vegetated areas for masking purposes during the postprocessing phase, excluding them for the digital elevation models (DEMs) generation or change detection purposes. However, vegetation can be extracted using sensors capable of capturing the near-infrared part of the spectrum, which cannot be recorded by visible (RGB) cameras. In this study, after reviewing different visible-band vegetation indices in various environments using different UAV technology, the influence of the spatial resolution of orthomosaics generated by photogrammetric processes in the vegetation extraction was examined. The triangular greenness index (TGI) index provided a high level of separability between vegetation and nonvegetation areas for all case studies in any spatial resolution. The efficiency of the indices remained fundamentally linked to the context of the scenario under investigation, and the correlation between spatial resolution and index incisiveness was found to be more complex than might be trivially assumed
Observing landscape changes around the nicosia old town center using multi-temporal datasets
No full textIn 1980s a significant boom in construction industry was witnessed in Cyprus. This paper explores the changes of land use that have occurred over the past 30 years around the historical capital of Nicosia, in particular around the core of the historic city defined by the Venetian walls. Further to some Open geospatial Data available within the national and regional geo-portals, the research has focused on the use and exploitation of freely accessible satellite imagery (such as Landsat and Sentinel imagery) and other archive aerial datasets in order to observe the most recent modifications of the urban landscapes. The changes occurred over time were observed using multi-spectral multi-temporal dataset with main aim to create thematic maps for further interpretation. The changes were hence identified, mapped and structured so as to emphasise different types and density of urban development affecting the surrounding landscapes and potential “hot-spots”. Such observations could be a valuable input to the future urban development of Nicosia
Unmanned aerial systems and spectroscopy for remote sensing applications in archaeology
No full textRemote sensing has open up new dimensions in archaeological research. Although there has been significant progress in increasing the resolution of space/aerial sensors and image processing, the detection of the crop (and soil marks) formations, which relate to buried archaeological remains, are difficult to detect since these marks may not be visible in the images if observed over different period or at different spatial/spectral resolution. In order to support the improvement of earth observation remote sensing technologies specifically targeting archaeological research, a better understanding of the crop/soil marks formation needs to be studied in detail. In this paper the contribution of both Unmanned Aerial Systems as well ground spectroradiometers is discussed in a variety of examples applied in the eastern Mediterranean region (Cyprus and Greece) as well in Central Europe (Hungary). In- situ spectroradiometric campaigns can be applied for the removal of atmospheric impact to simultaneous satellite overpass images. In addition, as shown in this paper, the systematic collection of ground truth data prior to the satellite/aerial acquisition can be used to detect the optimum temporal and spectral resolution for the detection of stress vegetation related to buried archaeological remains. Moreover, phenological studies of the crops from the area of interest can be simulated to the potential sensors based on their Relative Response Filters and therefore prepare better the satellite-aerial campaigns. Ground data and the use of Unmanned Aerial Systems (UAS) can provide an increased insight for studying the formation of crop and soil marks. New algorithms such as vegetation indices and linear orthogonal equations for the enhancement of crop marks can be developed based on the specific spectral characteristics of the area. As well, UAS can be used for remote sensing applications in order to document, survey and model cultural heritage and archaeological sites
Integrated method for tracking changes in archeolandscapes using remote and close-range technologies: Monitoring of change and risk assessment methodologies
No full textThe importance of visible built heritage and archeolandscapes for preservation of collective memory and identity is widely acknowledged across disciplines regarding heritage protection and valorisation. The complex analysis of archaeolandscape transformations through time needs multilevel geospatial information. To this purpose, it is necessary to consider different domains of technological tools but also an appropriate geospatial framework, applying a multi-scale, multitemporal and multi-sensor approach. In this way, the capabilities of new technologies can be further expanded aiming towards to an effective integration and improvement of preservation strategies and protection methodologies for cultural heritage sites. This paper illustrates the integration of in situ surveying campaigns, close range photogrammetry, aerial and satellite remote sensing imagery for identify change detection at the “Nea Paphos”, a UNESCO protected archaeological site of Cyprus. In particular, this paper examines the evolution of a buried archaeological feature (amphitheatre?) which is already known to experts but has not yet been excavated. Changes of shape and size have been documented, interpreted and mapped using resources covering a temporal arch of circa last 50 years. While soil and vegetation marks of the buried feature are very clear in the historic aerial imagery, these traces are disturbed on the recent images. An integrated method of detecting natural and physical consequences for evolving landscapes, using remote sensing techniques, airborne, and 3D photogrammetric models developed using open-source tools has been applied. Such integration is envisaged to (1) provide new kind of information and possible scenarios for retrieving geospatial knowledge of evolving archeolandscapes and their multiple layers of history and to (2) enable archaeologists, public administration and conservation professionals to pursue specific tailored-made preservation strategies of- specific archaeological sites and to support them in more informed decision making
The use and evaluation of a simulation game to teach professional practice skills to undergraduate Architecture students
No full textArchitects are currently grappling to exploit new forms of communication made possible with developments in internet communication. At the same time, the construction industry is in a state of flux as novel project management systems are being introduced. Students need to understand the first principles of project management within the context of our changing environment. One of the best ways for students to learn about the legalities of the construction process is through role play and simulation, but there is a Catch 22. Unless students have a basic understanding of project management, the contractual process can be confusing and intimidating. Even fifth and sixth year architecture student are reluctant to ask practitioners questions, for fear of appearing ignorant. This paper describes the use of a web-based simulation game to deliver the Management, Practice and Law syllabus to Architecture Students. The web-based game allows students to critically observe the transformation of designs into buildings through the exploration of the contract management process. A questionnaire survey was used to assess the efficacy of the simulation game as a learning tool, and in particular the effectiveness of the web-based simulation in facilitating the development of professional practice skills in undergraduate Architecture students. The initial results of the assessment indicate that the simulation game is both a useful and complementary adjunct to traditional teaching and learning methods, as observed through the evaluation of outcomes, and helpful in developing generic professional practice skills of undergraduate students. Further game development will require more formal evaluation over a series of uses
Bibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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