1,720,960 research outputs found
Automated detection of slum area change in Hyderabad, India using multitemporal satellite imagery
Full text linkThis paper presents an approach to automated identification of slum area change patterns in Hyderabad, India, using multi-year and multi-sensor very high resolution satellite imagery. It relies upon a lacunarity-based slum detection algorithm, combined with Canny- and LSD-based imagery pre-processing routines. This method outputs plausible and spatially explicit slum locations for the whole urban agglomeration of Hyderabad in years 2003 and 2010. The results indicate a considerable growth of area occupied by slums between these years and allow identification of trends in slum development in this urban agglomeration
Automated identification of slums in Hyderabad using high resolution satellite imagery
Full text linkSlums bilden einen wesentlichen Bestandteil vieler Stadtregionen des globalen Südens, wobei Indien die höchste Zahl an Slumbewohnern beherbergt. Die internationalen Unterschiede in der Definition des Begriffs "Slum" sowie Mängel bei der Datenerfassung haben eine hohe Fehlerwahrscheinlichkeit bei der Aufnahme von Slumbevölkerungszahlen und -standorten in globalem, nationalem und städtischem Massstab zur Folge. Das Hauptziel dieser Dissertation besteht darin, eine Vorgehensweise zur automatischen Erkennung von Slums mit Hilfe von hochauflösenden Satellitenbildern zu entwickeln, und diese Methode in der indischen Metropole Hyderabad anzuwenden. Diese Arbeit entwickelt ein mehrstufiges Satellitenbildbearbeitungsverfahren, welches in der Lage ist, eine schnelle Slumerkennung in Hyderabad durchzuführen. Das Verfahren beruht auf dem Verhältnis zwischen einem bestimmten Bereich räumlicher Heterogenität, ausgedrückt durch Lakunarität, und der Wahrscheinlichkeit, dass die Struktur eines Gebietes der Oberflächenstruktur eines Slums entspricht. Die Anwendung der hier vorgeschlagenen Methode produzierte zum ersten Mal einen plausiblen, räumlich kohärenten und politisch unverzerrten Datensatz über Slumstandorte und Slumbevölkerung für das gesamte Stadtgebiet von Hyderabad. Die Ergebnisse verdeutlichen die Unstimmigkeiten bei der bisherigen Erfassung der Slumbevölkerungszahlen sowie bei der offiziellen Anerkennung von Slums. Die multitemporale Satellitenbildauswertung zeigt ein Wachstum der Slumbevölkerungszahlen im Grossraum Hyderabad an und bietet Einblick in den zeitlich-räumlichen Slumwachstumprozess zwischen den Jahren 2003 und 2010. Diese Dissertation stellt einen wissenschaftlichen Beitrag zu den Themen Fernerkundung der Siedlungen und fortgeschrittene Bildbearbeitungsmethoden dar und bietet den unterschiedlichsten Parteien, für welche Slumdaten von Bedeutung sind, ein wichtiges Instrument.Slums are a pervasive feature of many urban regions in the global South, with India hosting the largest number of the global slum dwellers. Differences in slum definitions across countries and deficiencies of data collection are the cause of a large error margin in establishing slum population numbers and slum locations at a global, national and city scale. The main goal of this thesis is to develop an approach to automated identification of slums using sub-metre resolution satellite imagery, and to apply the new method to the slum-plagued South Indian megacity of Hyderabad. This dissertation establishes a multi-step satellite imagery analysis framework, which is capable of performing rapid identification of slums in Hyderabad without extensive ground surveys or manual image analysis. It is based on the relation of a specific range of spatial heterogeneity expressed through lacunarity to the probability of an area to be morphologically similar to the surface texture of a slum. The application of the proposed method has for the first time produced plausible, spatially coherent and politically unbiased slum coverage and slum population datasets for the whole of Hyderabad. The results expose inconsistencies in slum population data reporting and the slum recognition process currently in place in the city. The analysis of multitemporal remote sensing data indicates a considerable slum population increase in the metropolitan area of Hyderabad and provides an insight into spatiotemporal slum development patterns between the years 2003 and 2010. This dissertation contributes to the body of knowledge on remote sensing of human settlements and advanced image processing techniques and presents an essential instrument to be used by a the United Nations bodies, national and city governments as well as non-governmental organisations engaged in slum-related work
Texture-based identification of urban slums in Hyderabad, India using remote sensing data
No full textThis paper outlines a methodology to identify informal settlements out of high resolution satellite imagery using the concept of lacunarity. Principal component analysis and line detection algorithms were applied alternatively to obtain a high resolution binary representation of the city of Hyderabad, India and used to calculate lacunarity values over a 60 × 60 m grid. A number of ground truthing areas were used to classify the resulting datasets and to identify lacunarity ranges which are typical for settlement types that combine high density housing and small dwelling size – features characteristic for urban slums in India. It was discovered that the line detection algorithm is advantageous over principal component analysis in providing suitable binary datasets for lacunarity analysis as it is less sensitive to spectral variability within mosaicked imagery. The resulting slum location map constitutes an efficient tool in identifying particularly overcrowded areas of the city and can be used as a reliable source in vulnerability and resilience assessments at a later stage. The proposed methodology allows for rapid analysis and comparison of multi-temporal data and can be applied on many developing urban agglomerations around the world
A tool to predict environmental risk to UK rail infrastructure
No full textResearchers from the University of Southampton have collaborated with the rail industry's independent safety body RSSB on a pilot project for a geospatial risk model. The aim was to use the model to analyse and map derailments, suicides and slip, trip and fall risks across the UK rail network, initially in the Wessex region. The research has been extended to incorporate the impact of historic and real-time environmental data on rail risk. This paper presents a detailed description of the investigations, the resulting methodology and a prototype toolkit. The toolkit incorporates environmental conditions combined with rail incident data to help model and predict increased risk in real time
Evaluating the use of uncertainty visualization for exploratory analysis of land cover change: a qualitative expert user study
No full textExtensive research on geodata uncertainty has been conducted in the past decades, mostly related to modeling, quantifying, and communicating uncertainty. But findings on if and how users can incorporate this information into spatial analyses are still rare. In this paper we address these questions with a focus on land cover change analysis. We conducted semi-structured interviews with three expert groups dealing with change analysis in the fields of climate research, urban development, and vegetation monitoring. During the interviews we used a software prototype to show change scenarios that the experts had analyzed before, extended by visual depiction of uncertainty related to land cover change.This paper describes the study, summarizes results, and discusses findings as well as the study method. Participants came up with several ideas for applications that could be supported by uncertainty, for example, identification of erroneous change, description of change detection algorithm characteristics, or optimization of change detection parameters. Regarding the aspect of reasoning with uncertainty in land cover change data the interviewees saw potential in better-informed hypotheses and insights about change. Communication of uncertainty information to users was seen as critical, depending on the users’ role and expertize. We judge semi-structured interviews to be suitable for the purpose of this study and emphasize the potential of qualitative methods (workshops, focus groups etc.) for future uncertainty visualization studies
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
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
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