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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Statistical flow data applied to visual analytics

Nguyen, Phong Hai January 2011 (has links)
Statistical flow data such as commuting, migration, trade and money flows has gained manyinterests from policy makers, city planners, researchers and ordinary citizens as well. Therehave appeared numerous statistical data visualisations; however, there is a shortage of applicationsfor visualising flow data. Moreover, among these rare applications, some are standaloneand only for expert usages, some do not support interactive functionalities, and somecan only provide an overview of data. Therefore, in this thesis, I develop a web-enabled,highly interactive and analysis support statistical flow data visualisation application that addressesall those challenges.My application is implemented based on GAV Flash, a powerful interactive visualisationcomponent framework, thus it is inherently web-enabled with basic interactive features. Theapplication uses visual analytics approach that combines both data analysis and interactivevisualisation to solve cluttering issue, the problem of overlapping flows on the display. A varietyof analysis means are provided to analyse flow data efficiently including analysing bothflow directions simultaneously, visualising time-series flow data, finding most attracting regionsand figuring out the reason behind derived patterns. The application also supportssharing knowledge between colleagues by providing story-telling mechanism which allowsusers to create and share their findings as a visualisation story. Last but not least, the applicationenables users to embed the visualisation based on the story into an ordinary web-pageso that public stand a golden chance to derive an insight into officially statistical flow data.
2

MAPPING THE ECOLOGICAL INTERVIEW: GEOGRAPHIC VISUALIZATION FOR EXPLORING QUALITATIVE AND QUANTITATIVE ACTIVITY SPACE DATA

Cao, Yinghui January 2010 (has links)
There is ever greater recognition in the social and health sciences that neighborhood context should be incorporated in studying human behavior. In terms of analyzing urban human behavior, activity space data (i.e. data associated with an individual's home and routine activity locations) can offer diverse information. However, it is challenging to explore and interpret activity space data, which often involve qualitative and quantitative variables describing both the environment and people's travel-activities. This paper will present a prototype software environment to visualize qualitative and quantitative urban activity space data. A system is developed to visualize the data generated by the Ecological Interview, a method for collecting activity space data, social network data, and perception of place data. This application integrates data on adolescents' travel behaviors, as well as their individual, social and community resources, by mapping subjects' activity spaces using multiple visual attributes (e.g. symbolization, color). Users can investigate the activity space data through an interactive interface developed using a commercial GIS software package. The case studies show how the visualization assists in the exploratory studies of activity space data. The visualization can also be used in post-modeling analysis through in-depth investigation of the multiple attributes for the best-fit and worst-fit cases. / Geography
3

Visualization of Sensory Perception Descriptions

Prangova, Mimi January 2010 (has links)
Visualization of Sensory Perception Descriptors is a topic in the field of Information Visualization. It is concentrated on the research and development of methods for analyses of data related with human modalities description. One possibility for investigating sensory perception descriptors is analyzing a great number of wine tasting notes. This thesis is concerned with the visualization of wine tasting notes in order to aid linguistic analyses. It strives to find proper visualizations that will give a better insight into the language used in wine tasting notes. Two main processes are described in the following report. First it sets out the process of researching of different methods of information visualization that led to the final approach for representing the data. A number of concepts for text analyses are discussed and the most useful of them are developed further. Several approaches for text visualization and statistical information are combined to build a system for tasting notes analyses. The second part of the report describes the process of developing a prototype that implements the represented approaches and gives an opportunity for real testing and conclusions.
4

Developing and Evaluating a Geographic Information Dashboard to Improve Spatial Task Performance

Amariah Joanne Fischer January 1900 (has links)
Master of Arts / Department of Geography / J. M. Shawn Hutchinson / Information dashboards are decision-support tools that pull data from multiple sources and display those data on a single screen. Information dashboards are becoming common in fields such as medicine, computer science, and business, given their perceived ability to facilitate faster and more accurate assessments by users. However, there is very little peer-reviewed research on information dashboards that support this assumption. This research focuses on applying the concept of an information dashboard visualization within the spatial sciences and evaluating the effectiveness of a geographic information dashboard, or GID, on improving user performance related to spatial thinking tasks. A review of literature from multiple disciplines highlights what is, and what is not, understood about dashboard visualizations. Borrowing from ideas such as Cognitive Fit Theory and past work in evaluating the effectiveness of map animations, an appropriate method for evaluating the GID is proposed. A Web-based GID and an alternative “tabbed” visualization were developed using the R Shiny package to support an analysis of grassland vegetation development for a site located in northeastern Kansas. A controlled experiment was conducted using a survey completed by volunteer student participants who responded to a series of benchmark tasks related to the interpretation of 6 related maps and graphs. Data for three dependent variables (task completion time, task response accuracy, and an integrative measure of performance accounting for both time and accuracy) were collected directly from the survey or post-survey grading of responses. Three independent variables and their impact on spatial task performance were analyzed, including the type of visualization, assessed spatial thinking ability, and cognitive task type. Results showed that participants using the GID completed the benchmark tasks faster and more accurately, but that a users’ spatial thinking ability had the most significant influence on performance regardless of visualization. Evidence was found to support the idea that the GID improved spatial thinking performance, especially for users with more experience in spatial reasoning, and that the GID format may improve user performance beyond what is expected based on an independent assessment of spatial thinking ability.
5

Aspects of implicit and explicit human interactions with ubiquitous geographic information

Girardin, Fabien 14 July 2009 (has links)
El uso creciente de dispositivos móviles, infraestructuras inalámbricas e Internet está cambiando nuestra vida diaria, no solo la manera en que nos comunicamos o compartimos información, sino también cómo nos relacionamos con el entorno. A través de nuestras interacciones con estas tecnologías, accedemos y generamos una membrana de información que se cierne sobre los espacios donde vivimos y que visitamos. Sin embargo, esta capa de información solo modela de manera imperfecta la realidad debido a una digitalización tosca y a limitaciones tecnológicas, que hacen peligrar la interacción humana. Por otro lado, la presencia de esta información geográfica ubicua generada por los usuarios abre nuevas perspectivas para la comprensión de las actividades humanas en el espacio y el tiempo. Esta tesis acepta el reto de investigar estos aspectos de las interacciones humanas con la información geográfica ubicua. Con un enfoque cualitativo y cuantitativo, discernimos las implicaciones de la integración de información geográfica ubicua y las resultantes estrategias de los usuarios para hacer frente a la incertidumbre espacial. Entonces, explotamos esta contribución para analizar enfoques novedosos con el objetivo de inferir actividades espacio-temporales de individuos y grupos respetando su privacidad. Demostramos la aplicabilidad de nuestras soluciones en los ámbitos de la investigación de mercados y el urbanismo. / The increasing use of mobile devices, wireless infrastructures, and the Internet is changing our daily lives, not only in the way we communicate with each other or share information but also how we relate to the environment. Through our interactions with these technologies we access and generate an informational membrane, hovering over the spaces we live in and visit. However, this information layer only imperfectly models the reality due to coarse digitization and technological limitations, challenging the human interaction. On the other hand, the presence of this user-generated ubiquitous geographic information opens novel perspectives in understanding human activities over space and time. This thesis takes on the challenge of exploring these aspects of human interactions with ubiquitous geographic information. Through qualitative lenses, we discern the implications of the integration of ubiquitous geographic information and the resulting users strategies to cope with spatial uncertainty. Then, we exploit this contribution to explore novel approaches to infer individuals and groups time-space activities with respect to their privacy. We demonstrate the applicability of our solutions in the domains of market research and urbanism.
6

An iterative design process for visualizing historical air temperature recordings effectively in a single display : A user study on narrative visualizations of geospatial time-dependent data / En iterativ designprocess for att visualisera historiska lufttemperaturer mätningar effektivt i en enda vy : En användarstudie på narrativa visualiseringar av geografisk och tidsberoende data

Kangas, Jussi January 2021 (has links)
How to represent data visually in an intuitive and effective way for gaining quick insights is something that the field of visualization deals with. Effective in this context means that a visualization can be understood accurately or rapidly by the viewer. However, how to visualize geospatial time series data effectively is challenging. The challenge consists of how to visualize geospatial time-dependent data in a single view that can provide both an effective overview and details of the data set. With three or more data dimensions the available coding options grows; hence, the challenge consists in combining several visual coding and viewing options into a single effective view. This thesis investigated visualization guidelines that should promote effectivness for a visualization of geospatial time-dependent data. Furthermore, in this project the data set consisted of historical air temperature measurements in Sweden, which has both geospatial and time-dependent features. The guidelines where used in an iterative design process to redesign an existing geospatial time series visualization. The goal of the redesign was to increase the effectiveness of the existing visualization. An alternative visualization was created and compared to the original visualization in a user study. The results indicate that these users experienced the alternative visualization as more effective than the original. However, the performance of the participants on four tasks indicates that the alternative visualization is not more effective. Furthermore, compared to related work the alternative visualization is not more effective. In conclusion, the alternative visualization is harder to learn than the original which may have an effect on the user’s performance. However, once the visualization is learned, then it may be more effective than the original visualization. Additionally, the use of guidelines was helpful in the design process but, in this case, did not guarantee an effective visualization. / Hur data bör representeras visuellt på ett intuitivt och effektivt sätt undersöks i det vetenskapliga fältet om visualiseringar. Vidare är det utmanande hur geografiska tidsserier ska visualiserar. Utmaningen består i hur en enda visualiserings vy ska skapas som både kan ge en överblick över data och detaljer om specifika data punkter. Anledning till att detta är utmanande är att med fler data dimensioner blir även de möjliga visuella kodnings möjligheterna flera. Därför består utmaningen i hur olika visuella kodningssätt och vyer ska kombineras i en enda vy effektivt. För att designa en effektiv vy undersöktes olika designriktlinjer kopplade till effektivitet. Dessa riktlinjer användes sedan för att designa om en existerande geografisk tidsserie visualisering in en iterativ designprocess. Data som visualiserades var historiska lufttemperaturmätningar i Sverige, en datamängd med både geografiska och tidsberoende komponenter. Den skapade alternativa visualiseringen jämfördes med originalet med hänsyn till effektivitet i en användarstudie. Resultaten tyder på att användarna uppfattar den alternativa visualiseringen som mer effektiv än originalet. Men prestations resultatet på fyra uppgifter tyder inte på att den alternativa visualiseringen skulle vara effektivare. Vidare, jämfört med relaterade arbeten är inte den alternative visualiseringen mer effektiv. Sammanfattningsvis är den alternativa visualiseringen svårare att lära sig än originalet, vilken kan påverka användarnas prestation. Men när användarna lärt sig att använda den alternativa visualiseringen, kan den alternativa vara effektivare att använda än originalet. Vidare är designriktlinjerna användbara i en designprocess men, ingen garanti för en effektiv visualisering i detta fall.
7

Climate vulnerability assessment methodology : Agriculture under climate change in the Nordic region / Metodologi för bedömning av klimatsårbarhet : Nordiskt jordbruk i ett förändrat klimat

Wiréhn, Lotten January 2017 (has links)
Food security and climate change mitigation are crucial missions for the agricultural sector and for global work on sustainable development. Concurrently, agricultural production is directly dependent on climatic conditions, making climate change adaptation strategies essential for the agricultural sector. There is consequently a need for researchers, planners, and practitioners to better understand how, why, and to what extent agriculture is vulnerable to climate change. Such analyses involve challenges in relation to the complex social– ecological character of the agricultural system and to the multiple conceptualizations and approaches used in analysing vulnerability. The aim of this thesis is to identify how vulnerability assessments can be used to represent climate-related vulnerability in Nordic agriculture, in order to advance the methodological development of indicator-based and geographic visualization methods. The following research questions are addressed: (i) How can agricultural vulnerability to climate change and variability in the Nordic countries be characterized? (ii) How do selections, definitions, and emphases of indicators influence how vulnerability is assessed? (iii) How do estimates of vulnerability vary depending on the methods used in assessments? (iv) How can geographic visualization be applied in integrated vulnerability assessments? This thesis analyses and applies various vulnerability assessment approaches in the context of Nordic agriculture. This thesis demonstrates that various methods for composing vulnerability indices result in significantly different outcomes, despite using the same set of indicators. A conceptual framework for geographic visualization approaches to vulnerability assessments was developed for the purpose of creating transparent and interactive assessments regarding the indicating variables, methods and assumptions applied, i.e., opening up the ‘black box’ of composite indices. This framework served as the foundation for developing the AgroExplore geographic visualization tool. The tool enables the user to interactively select, categorize, and weight indicators as well as to explore the data and the spatial patterns of the indicators and indices. AgroExplore was used in focus group settings with experts in the Swedish agricultural sector. The visualization-supported dialogue results confirm the difficulty of selecting and constructing indicators, including different perceptions of what indicators actually indicate, the assumption of linear relationships between the indicators and vulnerability, and, consequently, that the direction of the relationship is predefined for each indicator. This thesis further points at the inherent complexity of agricultural challenges and opportunities in the context of climate change as such. It is specifically emphasized that agricultural adaptation policies and measures involve trade-offs between various environmental and socio–economic objectives, and that their implementation could furthermore entail unintended consequences, i.e., potential maladaptive outcomes. Nevertheless, it proved difficult to validate indicators due to, e.g. matters of scale and data availability. While heavy precipitation and other extreme weather events are perceived as the most relevant drivers of climate vulnerability by the agricultural experts participating in this study, statistical analyses of historical data identified few significant relationships between crop yield losses and heavy precipitation. In conclusion, this thesis contributes to the method development of composite indices and indicator-based vulnerability assessment. A key conclusion is that assessments are method dependent and that indicator selection is related to aspects such as the system’s spatial scale and location as well as to indicator thresholds and defined relationships with vulnerability, recognizing the contextual dependency of agricultural vulnerability. Consequently, given the practicality of indicator-based methods, I stress with this thesis that future vulnerability studies must take into account and be transparent about the principles and limitations of indicator-based assessment methods in order to ensure their usefulness, validity, and relevance for guiding adaptation strategies. / För jordbrukssektorn och global hållbar utveckling i stort är matsäkerhet och mitigering av klimatförändringar viktiga angelägenheter. Samtidigt är jordbruksproduktionen ofta direkt beroende av klimatförhållanden, vilket gör klimatanpassningsstrategier mycket centrala för sektorn. Forskare, planerare och aktörer behöver förstå hur, varför och i vilken omfattning jordbruket är sårbart inför klimatförändringar. Sådana analyser inbegriper även de utmaningar som skapas genom jordbrukets komplexa socio-ekologiska karaktär, och de många utgångspunkter och tillvägagångssätt som används för att bedöma sårbarhet. Syftet med denna avhandling är att identifiera hur sårbarhetsbedömningar kan representera klimatrelaterad sårbarhet i nordiskt jordbruk, och i och med detta har avhandlingen som avsikt att utveckla metodologin för indikatorbaserade- och geografiska visualiseringsmetoder. Följande forskningsfrågor avhandlas: (i) Hur kan det nordiska jordbrukets sårbarhet inför klimatvariation och förändringar karaktäriseras? (ii) Hur påverkar urval, definitioner och betoningar av indikatorer bedömningar av sårbarhet? (iii) Hur varierar uppskattningar med bedömningsmetod? (iv) Hur kan geografisk visualisering användas i integrerade såbarhetsbedömningar? För att svara på dessa frågor analyseras och tillämpas olika tillvägagångssätt att bedöma sårbarhet inom nordiskt jordbruk. Avhandlingen visar att olika metoder för sårbarhetskompositindex resulterar i signifikanta skillnader mellan index, trots att samma indikatorer och data används. Ett konceptuellt ramverk för sårberhetsbedömningar där geografisk visualisering används, har utvecklats för att möjliggöra transparens avseende till exempel. vilka variabler, metoder och antaganden som används i kompositindex. Detta ramverk har följaktligen legat till grund för att utveckla ett geografiskt visualiseringsverktyg – AgroExplore. Verktyget möjliggör interaktivitet där användaren kan välja, kategorisera och vikta indikatorer, och dessutom utforska data och spatiala mönster av indikatorer och kompositindex. AgroExplore användes i denna avhandling för att stödja fokusgruppdialoger med experter inom den svenska jordbrukssektorn. Resultaten från dessa workshops bekräftar svårigheten med att välja och skapa indikatorer. Dessa svårigheter innefattar olika uppfattningar om vad indikatorer representerar, antagandet om linjära samband mellan indikatorerna och sårbarhet, och följaktligen att sambandens riktning är fördefinierade för respektive indikator. Utöver de konceptuella och metodologiska utmaningarna med sårbarhetsbedömningar visar avhandlingen på komplexa svårigheter och möjligheter för jordbruket vid klimatförändringar. Särskilt framhålls att klimatanpassningspolitik och åtgärder inom jordbruket medför konflikter och avvägningar mellan olika miljö- och socio-ekonomiska mål. Implementering av sådana anpassningsåtgärder kan vidare innebära oönskade konsekvenser, så kallad missanpassning. Trots ökad kunskap gällande nordiska jordbrukets sårbarhet inför klimatförändringar har det visats sig vara svårt att statistiskt validera indikatorer på grund av, exempelvis, skalproblematik och datatillgänglighet. Samtidigt som experterna ansåg att kraftig nederbörd och andra extrema väderhändelser är de mest relevanta drivkrafterna till klimatsårbarhet visar den statistiska analysen av historiska data på få signifikanta samband mellan förlorad skördeavkastning och kraftig nederbörd. Denna avhandling bidrar till metodutveckling av kompositindex och indikatorbaserade metoder för sårbarhetsbedömningar. En viktig slutsats är att bedömningar är metodberoende och att valet av indikatorer är relaterat till aspekter såsom systemets utbredning och den spatiala skalan av bedömningen. Även indikatorernas tröskelvärden och hur deras relation till sårbarhet är definierade anses vara viktiga faktorer som påverkar hur indikatorer representerar sårbarhet, vilket visar på sårbarhetsbedömningars kontextuella beroende. I och med de rådande bristerna hos indikatorbaserade metoder, som bland annat har identifierats i denna avhandling, vill jag framhålla vikten av att sårbarhetsbedömningar bör vara transparanta gällande den tillämpade metodens principer, antaganden och begräsningar. Detta för att säkerställa användbarhet, giltighet och relevans, om metoden och bedömningen ska ligga till grund för anpassningsstrategier hos såväl politiker, planerare och lantbrukare. / <p>This is deliverable of the Nordic Centre of Excellence for Strategic Adaptation Research (NORD-STAR), funded by the Nordic Top-level Research Initiative Sub-programme ‘Effects Studies and Adaptation to Climate Change’.</p><p>The work has also been supported by the Swedish Research Council FORMAS under Grant No. 2013-1557 ‘Identifying thresholds for maladaptation in Nordic agriculture’</p>

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