684 research outputs found

    Revisiting the capitalization of public transport accessibility into residential land value: an empirical analysis drawing on Open Science

    Get PDF
    Background: The delivery and effective operation of public transport is fundamental for a for a transition to low-carbon emission transport systems’. However, many cities face budgetary challenges in providing and operating this type of infrastructure. Land value capture (LVC) instruments, aimed at recovering all or part of the land value uplifts triggered by actions other than the landowner, can alleviate some of this pressure. A key element of LVC lies in the increment in land value associated with a particular public action. Urban economic theory supports this idea and considers accessibility to be a core element for determining residential land value. Although the empirical literature assessing the relationship between land value increments and public transport infrastructure is vast, it often assumes homogeneous benefits and, therefore, overlooks relevant elements of accessibility. Advancements in the accessibility concept in the context of Open Science can ease the relaxation of such assumptions. Methods: This thesis draws on the case of Greater Mexico City between 2009 and 2019. It focuses on the effects of the main public transport network (MPTN) which is organised in seven temporal stages according to its expansion phases. The analysis incorporates location based accessibility measures to employment opportunities in order to assess the benefits of public transport infrastructure. It does so by making extensive use of the open-source software OpenTripPlanner for public transport route modelling (≈ 2.1 billion origin-destination routes). Potential capitalizations are assessed according to the hedonic framework. The property value data includes individual administrative mortgage records collected by the Federal Mortgage Society (≈ 800,000). The hedonic function is estimated using a variety of approaches, i.e. linear models, nonlinear models, multilevel models, and spatial multilevel models. These are estimated by the maximum likelihood and Bayesian methods. The study also examines possible spatial aggregation bias using alternative spatial aggregation schemes according to the modifiable areal unit problem (MAUP) literature. Results: The accessibility models across the various temporal stages evidence the spatial heterogeneity shaped by the MPTN in combination with land use and the individual perception of residents. This highlights the need to transition from measures that focus on the characteristics of transport infrastructure to comprehensive accessibility measures which reflect such heterogeneity. The estimated hedonic function suggests a robust, positive, and significant relationship between MPTN accessibility and residential land value in all the modelling frameworks in the presence of a variety of controls. The residential land value increases between 3.6% and 5.7% for one additional standard deviation in MPTN accessibility to employment in the final set of models. The total willingness to pay (TWTP) is considerable, ranging from 0.7 to 1.5 times the equivalent of the capital costs of the bus rapid transit Line-7 of the MetrobĂșs system. A sensitivity analysis shows that the hedonic model estimation is sensitive to the MAUP. In addition, the use of a post code zoning scheme produces the closest results compared to the smallest spatial analytical scheme (0.5 km hexagonal grid). Conclusion: The present thesis advances the discussion on the capitalization of public transport on residential land value by adopting recent contributions from the Open Science framework. Empirically, it fills a knowledge gap given the lack of literature around this topic in this area of study. In terms of policy, the findings support LVC as a mechanism of considerable potential. Regarding fee-based LVC instruments, there are fairness issues in relation to the distribution of charges or exactions to households that could be addressed using location based measures. Furthermore, the approach developed for this analysis serves as valuable guidance for identifying sites with large potential for the implementation of development based instruments, for instance land readjustments or the sale/lease of additional development rights

    Symbolic Synthesis of Neural Networks

    Full text link
    Neural networks adapt very well to distributed and continuous representations, but struggle to generalize from small amounts of data. Symbolic systems commonly achieve data efficient generalization by exploiting modularity to benefit from local and discrete features of a representation. These features allow symbolic programs to be improved one module at a time and to experience combinatorial growth in the values they can successfully process. However, it is difficult to design a component that can be used to form symbolic abstractions and which is adequately overparametrized to learn arbitrary high-dimensional transformations. I present Graph-based Symbolically Synthesized Neural Networks (G-SSNNs), a class of neural modules that operate on representations modified with synthesized symbolic programs to include a fixed set of local and discrete features. I demonstrate that the choice of injected features within a G-SSNN module modulates the data efficiency and generalization of baseline neural models, creating predictable patterns of both heightened and curtailed generalization. By training G-SSNNs, we also derive information about desirable semantics of symbolic programs without manual engineering. This information is compact and amenable to abstraction, but can also be flexibly recontextualized for other high-dimensional settings. In future work, I will investigate data efficient generalization and the transferability of learned symbolic representations in more complex G-SSNN designs based on more complex classes of symbolic programs. Experimental code and data are available at https://github.com/shlomenu/symbolically_synthesized_networks .Comment: 8 pages, 1 figure. Minor formula correction and minor textual revisio

    Functional space-time properties of team synergies in high-performance football

    Get PDF
    This thesis aimed to investigate the performance of high-level teams in football, through the analysis of the interactions of their players in the context of the game, as these interactions result in functional effects that could not otherwise be achieved (synergies). From a spatial point of view, we argue that the understanding of collective “payoffs” emerging from players’ interactions and their behavioural patterns, can be accomplished through ”Delaunay triangulations” and consequent ”Voronoi diagrams”. Analysing the positional data (22 players and the ball) in 20 games of the French premier league, in this thesis we essentially sought to focus on territorial dominance as a variable that potentially captures the spatial affordances perceived by players. Whether from a collective global point of view or from a perspective of the local interactions that arise in the game landscape. Supported by the ecological dynamics and the synergism hypothesis, in this thesis we begin by demonstrating the existing connection between the territorial dominance of a team and the offensive effectiveness, as well as the absence of temporal overlap between the ball possession status and territorial dominance. Similarly, we also demonstrated that the space dominance of each player, which contributes to the territorial dominance of the team as a whole, is constrained by the team’s formation and the role assumed by each player in this collective framework. In order to understand the dynamics of interactions between players and the functional effects that come from it, we then focus on two tasks that are related to collective performance: the pass and the shot. Reflecting on the need to find methods that capture how the distribution of players on the pitch influences the functional degrees of freedom of a team as a whole and the passing opportunities that emerge from it. And, at the level of finishing situations, how the dominance of space can be included in the quantification of the value that each player assigns to occupy a certain place in the game landscape, and which is at the basis of their decision-making (shoot or pass the ball to another teammate possibly better ”positioned”). In sum, through the initial conceptual framework and the applied studies, we argue that the analysis of team performance should focus on the functional synergies that result from interactions between players. In this way, we demonstrate, through some examples, how the methods and conclusions taken from this thesis can be applied in practice by football coaches.Esta tese teve como objetivo investigar a performance de equipas de alto nĂ­vel no futebol, atravĂ©s da anĂĄlise das interaçÔes dos seus jogadores no contexto do jogo pois daĂ­ resultam efeitos funcionais que apenas sĂŁo atingidos atravĂ©s dessas mesmas interaçÔes (sinergias). De um ponto de vista espacial, defendemos que o estudo glocal das interaçÔes entre os jogadores para a compreensĂŁo do rendimento coletivo, pode ser realizado atravĂ©s de “triangulaçÔes de Delaunay” e consequentes “diagramas de Voronoi”. Analisando os dados posicionais dos 22 jogadores e da bola, em 20 jogos da primeira liga francesa, nesta tese procurĂĄmos essencialmente nos focar sobre o domĂ­nio territorial enquanto variĂĄvel que capta potencialmente as affordances espaciais percebidas pelos jogadores. Seja de um ponto de vista global coletivo, seja numa perspetiva das interaçÔes locais que surgem na paisagem de jogo. Suportados pela dinĂąmica ecolĂłgica e pela hipĂłtese do sinergismo, nesta tese começamos por demonstrar a ligação existente entre o domĂ­nio territorial das equipas e a sua efetividade ofensiva, bem como a inexistĂȘncia de uma sobreposição temporal entre a posse de bola e esse domĂ­nio. De igual forma, tambĂ©m demonstrĂĄmos que o domĂ­nio do espaço de cada jogador, que contribui para o domĂ­nio territorial da equipa no seu todo, Ă© constrangido pelo sistema de jogo das equipas e pelo papel assumido por cada jogador neste referencial coletivo. No sentido de compreender a dinĂąmica das interaçÔes entre os jogadores e os efeitos funcionais que daĂ­ advĂȘm, focamo-nos seguidamente em duas tarefas que estĂŁo relacionadas com a performance coletiva: o passe e o remate. Refletindo sobre a necessidade de encontrar mĂ©todos que captem de que forma a distribuição dos jogadores em campo influencia os graus de liberdade funcionais de uma equipa no seu todo e as oportunidades de passe que daĂ­ emergem. E, ao nĂ­vel das situaçÔes de finalização, de que forma o domĂ­nio do espaço poderĂĄ ser incluĂ­do na quantificação do valor que cada jogador atribui a ocupar um determinador espaço na paisagem de jogo e que estĂĄ na base da sua tomada de decisĂŁo (rematar ou passar a bola para outro colega eventualmente melhor “posicionado”). Em suma, atravĂ©s do enquadramento conceptual inicial e dos estudos aplicados, defendemos que o estudo da performance das equipas deverĂĄ se centrar nas sinergias funcionais que resultam das interaçÔes entre os jogadores. Desta forma, demonstramos, atravĂ©s de alguns exemplos, como Ă© que os mĂ©todos e ilaçÔes retirados desta tese poderĂŁo ser aplicados na prĂĄtica pelos treinadores de futebol

    Velocity-Based LOD Reduction in Virtual Reality: A Psychometric Approach

    Full text link
    Virtual Reality headsets enable users to explore the environment by performing self-induced movements. The retinal velocity produced by such motion reduces the visual system's ability to resolve fine detail. We measured the impact of self-induced head rotations on the ability to detect quality changes of a realistic 3D model in an immersive virtual reality environment. We varied the Level-of-Detail (LOD) as a function of rotational head velocity with different degrees of severity. Using a psychophysical method, we asked 17 participants to identify which of the two presented intervals contained the higher quality model under two different maximum velocity conditions. After fitting psychometric functions to data relating the percentage of correct responses to the aggressiveness of LOD manipulations, we identified the threshold severity for which participants could reliably (75\%) detect the lower LOD model. Participants accepted an approximately four-fold LOD reduction even in the low maximum velocity condition without a significant impact on perceived quality, which suggests that there is considerable potential for optimisation when users are moving (increased range of perceptual uncertainty). Moreover, LOD could be degraded significantly more in the maximum head velocity condition, suggesting these effects are indeed speed dependent

    Aggressive saliency-aware point cloud compression

    Full text link
    The increasing demand for accurate representations of 3D scenes, combined with immersive technologies has led point clouds to extensive popularity. However, quality point clouds require a large amount of data and therefore the need for compression methods is imperative. In this paper, we present a novel, geometry-based, end-to-end compression scheme, that combines information on the geometrical features of the point cloud and the user's position, achieving remarkable results for aggressive compression schemes demanding very small bit rates. After separating visible and non-visible points, four saliency maps are calculated, utilizing the point cloud's geometry and distance from the user, the visibility information, and the user's focus point. A combination of these maps results in a final saliency map, indicating the overall significance of each point and therefore quantizing different regions with a different number of bits during the encoding process. The decoder reconstructs the point cloud making use of delta coordinates and solving a sparse linear system. Evaluation studies and comparisons with the geometry-based point cloud compression (G-PCC) algorithm by the Moving Picture Experts Group (MPEG), carried out for a variety of point clouds, demonstrate that the proposed method achieves significantly better results for small bit rates

    The Impact of Vowel Inventory Size and Linguistic Environment when Learning Two Languages: The Case of English and Greek

    Get PDF
    Producing phonemic contrasts in two typologically different languages, can prove a difficult task for speakers of those languages, even experienced ones (for instance, Boersma & Escudero, 2008; Kivistö-de Souza & Carlet, 2014), from birth or otherwise. This thesis discusses the effects of linguistic environment and phonemic inventories in the production of British English vowels. Greek and English were chosen as a language pair for further investigation, due to the fact that their vocalic inventories differ significantly in terms of the number of phonemes each has, the phonemic categories identified, as well as the vowel features in each. In order to explore the role of the linguistic environment, groups of bilingual Greek - English children based in the United Kingdom and in Greece took part in the first round of experiments. In order to explore further the role of phonemic inventories a group of native Greek second language learners of English also took part in the same set of tasks. The productions of British English vowels and vowel contrasts by each participant group was assessed by a series of speech production tasks analysing acoustic properties of the vowel categories in question. Bilingual children in Greece performed in a similar manner to monolingual controls, however, children raised in the UK deviated from monolingual norms. Quality of input and amount of exposure to each language in the two linguistic environments seem to be predicting factors for vowel production outcomes. Native Greek second language learners of English produced British English vowels similarly to monolingual controls when it came to both spectral and temporal cues. This could be attributed to the amount of experience second language learners had with English throughout their lifespan

    Towards Generalizable Deep Image Matting: Decomposition, Interaction, and Merging

    Get PDF
    Image matting refers to extracting the precise alpha mattes from images, playing a critical role in many downstream applications. Despite extensive attention, key challenges persist and motivate the research presented in this thesis. One major challenge is the reliance of auxiliary inputs in previous methods, hindering real-time practicality. To address this, we introduce fully automatic image matting by decomposing the task into high-level semantic segmentation and low-level details matting. We then incorporate plug-in modules to enhance the interaction between the sub-tasks through feature integration. Furthermore, we propose an attention-based mechanism to guide the matting process through collaboration merging. Another challenge lies in limited matting datasets, resulting in reliance on composite images and inferior performance on images in the wild. In response, our research proposes a composition route to mitigate the discrepancies and result in remarkable generalization ability. Additionally, we construct numerous large datasets of high-quality real-world images with manually labeled alpha mattes, providing a solid foundation for training and evaluation. Moreover, our research uncovers new observations that warrant further investigation. Firstly, we systematically analyze and address privacy issues that have been neglected in previous portrait matting research. Secondly, we explore the adaptation of automatic matting methods to non-salient or transparent categories beyond salient ones. Furthermore, we collaborate with language modality to achieve a more controllable matting process, enabling specific target selection at a low cost. To validate our studies, we conduct extensive experiments and provide all codes and datasets through the link (https://github.com/JizhiziLi/). We believe that the analyses, methods, and datasets presented in this thesis will offer valuable insights for future research endeavors in the field of image matting

    Multiscale visualization approaches for Volunteered Geographic Information and Location-based Social Media

    Get PDF
    Today, “zoomable” maps are a state-of-the-art way to explore the world, available to anyone with Internet access. However, the process of creating this visualization has been rather loosely investigated and documented. Nevertheless, with an increasing amount of available data, interactive maps have become a more integral approach to visualizing and exploring big datasets and user-generated data. OpenStreetMap and online platforms such as Twitter and Flickr offer application programming interfaces (APIs) with geographic information. They are well-known examples of this visualization challenge and are often used as examples. In addition, an increasing number of public administrations collect open data and publish their data sets, which makes the task of visualization even more relevant. This dissertation deals with the visualization of user-generated geodata as a multiscale map. The basics of today’s multiscale maps—their history, technologies, and possibilities—are explored and abstracted. This work introduces two new multiscale-focused visualization approaches for point data from volunteered geographic information (VGI) and location-based social media (LBSM). One contribution of this effort is a visualization methodology for spatially referenced information in the form of point geometries, using nominally scaled data from social media such as Twitter or Flickr. Typical for this data is a high number of social media posts in different categories—a post on social media corresponds to a point in a specific category. Due to the sheer quantity and similar characteristics, the posts appear generic rather than unique. This type of dataset can be explored using the new method of micro diagrams to visualize the dataset on multiple scales and resolutions. The data is aggregated into small grid cells, and the numerical proportion is shown with small diagrams, which can visually merge into heterogenous areas through colors depicting a specific category. The diagram sizes allow the user to estimate the overall number of aggregated points in a grid cell. A different visualization approach is proposed for more unique points, considered points of interest (POI), based on the selection method. The goal is to identify more locally relevant points from the data set, considered more important compared to other points in the neighborhood, which are then compared by numerical attribute. The method, derived from topographic isolation and called discrete isolation, is the distance from one point to the next with a higher attribute value. By using this measure, the most essential points can be easily selected by choosing a minimum distance and producing a homogenous spatial of the selected points within the chosen dataset. The two newly developed approaches are applied to multiscale mapping by constructing example workflows that produce multiscale maps. The publicly available multiscale mapping workflows OpenMapTiles and OpenStreetMap Carto, using OpenStreetMap data, are systematically explored and analyzed. The result is a general workflow for multiscale map production and a short overview of the toolchain software. In particular, the generalization approaches in the example projects are discussed and these are classified into cartographic theories on the basis of literature. The workflow is demonstrated by building a raster tile service for the micro diagrams and a vector tile service for the discrete isolation, able to be used with just a web browser. In conclusion, these new approaches for point data using VGI and LBSM allow better qualitative visualization of geodata. While analyzing vast global datasets is challenging, exploring and analyzing hidden data patterns is fruitful. Creating this degree of visualization and producing maps on multiple scales is a complicated task. The workflows and tools provided in this thesis will make map production on a worldwide scale easier.:1 Introduction 1 1.1 Motivation .................................................................................................. 3 1.2 Visualization of crowdsourced geodata on multiple scales ............ 5 1.2.1 Research objective 1: Visualization of point collections ......... 6 1.2.2 Research objective 2: Visualization of points of interest ......... 7 1.2.3 Research objective 3: Production of multiscale maps ............. 7 1.3 Reader’s guide ......................................................................................... 9 1.3.1 Structure ........................................................................................... 9 1.3.2 Related Publications ....................................................................... 9 1.3.3 Formatting and layout ................................................................. 10 1.3.4 Online examples ........................................................................... 10 2 Foundations of crowdsourced mapping on multiple scales 11 2.1 Types and properties of crowdsourced data .................................. 11 2.2 Currents trends in cartography ......................................................... 11 2.3 Definitions .............................................................................................. 12 2.3.1 VGI .................................................................................................. 12 2.3.2 LBSM .............................................................................................. 13 2.3.3 Space, place, and location......................................................... 13 2.4 Visualization approaches for crowdsourced geodata ................... 14 2.4.1 Review of publications and visualization approaches ........... 14 2.4.2 Conclusions from the review ...................................................... 15 2.4.3 Challenges mapping crowdsourced data ................................ 17 2.5 Technologies for serving multiscale maps ...................................... 17 2.5.1 Research about multiscale maps .............................................. 17 2.5.2 Web Mercator projection ............................................................ 18 2.5.3 Tiles and zoom levels .................................................................. 19 2.5.4 Raster tiles ..................................................................................... 21 2.5.5 Vector tiles .................................................................................... 23 2.5.6 Tiling as a principle ..................................................................... 25 3 Point collection visualization with categorized attributes 26 3.1 Target users and possible tasks ....................................................... 26 3.2 Example data ......................................................................................... 27 3.3 Visualization approaches .................................................................... 28 3.3.1 Common techniques .................................................................... 28 3.3.2 The micro diagram approach .................................................... 30 3.4 The micro diagram and its parameters ............................................ 33 3.4.1 Aggregating points into a regular structure ............................ 33 3.4.2 Visualizing the number of data points ...................................... 35 3.4.3 Grid and micro diagrams ............................................................ 36 3.4.4 Visualizing numerical proportions with diagrams .................. 37 3.4.5 Influence of color and color brightness ................................... 38 3.4.6 Interaction options with micro diagrams .................................. 39 3.5 Application and user-based evaluation ............................................ 39 3.5.1 Micro diagrams in a multiscale environment ........................... 39 3.5.2 The micro diagram user study ................................................... 41 3.5.3 Point collection visualization discussion .................................. 47 4 Selection of POIs for visualization 50 4.1 Approaches for point selection .......................................................... 50 4.2 Methods for point selection ................................................................ 51 4.2.1 Label grid approach .................................................................... 52 4.2.2 Functional importance approach .............................................. 53 4.2.3 Discrete isolation approach ....................................................... 54 4.3 Functional evaluation of selection methods .................................... 56 4.3.1 Runtime comparison .................................................................... 56 4.3.2 Use cases for discrete isolation ................................................ 57 4.4 Discussion of the selection approaches .......................................... 61 4.4.1 A critical view of the use cases ................................................. 61 4.4.2 Comparing the approaches ........................................................ 62 4.4.3 Conclusion ..................................................................................... 64 5 Creating multiscale maps 65 5.1 Examples of multiscale map production .......................................... 65 5.1.1 OpenStreetMap Infrastructure ................................................... 66 5.1.2 OpenStreetMap Carto ................................................................. 67 5.1.3 OpenMapTiles ............................................................................... 73 5.2 Methods of multiscale map production ............................................ 80 5.2.1 OpenStreetMap tools ................................................................... 80 5.2.2 Geoprocessing .............................................................................. 80 5.2.3 Database ........................................................................................ 80 5.2.4 Creating tiles ................................................................................. 82 5.2.5 Caching .......................................................................................... 82 5.2.6 Styling tiles .................................................................................... 82 5.2.7 Viewing tiles ................................................................................... 83 5.2.8 The stackless approach to tile creation ................................... 83 5.3 Example workflows for creating multiscale maps ........................... 84 5.3.1 Raster tiles: OGC services and micro diagrams .................... 84 5.3.2 Vector tiles: Slippy map and vector tiles ................................. 87 5.4 Discussion of approaches and workflows ....................................... 90 5.4.1 Map production as a rendering pipeline .................................. 90 5.4.2 Comparison of OpenStreetMap Carto and OpenMapTiles .. 92 5.4.3 Discussion of the implementations ........................................... 93 5.4.4 Generalization in map production workflows .......................... 95 5.4.5 Conclusions ................................................................................. 101 6 Discussion 103 6.1 Development for web mapping ........................................................ 103 6.1.1 The role of standards in map production .............................. 103 6.1.2 Technological development ..................................................... 103 6.2 New data, new mapping techniques? ............................................. 104 7 Conclusion 106 7.1 Visualization of point collections ..................................................... 106 7.2 Visualization of points of interest ................................................... 107 7.3 Production of multiscale maps ........................................................ 107 7.4 Synthesis of the research questions .............................................. 108 7.5 Contributions ....................................................................................... 109 7.6 Limitations ............................................................................................ 110 7.7 Outlook ................................................................................................. 111 8 References 113 9 Appendix 130 9.1 Zoom levels and Scale ...................................................................... 130 9.3 Full information about selected UGC papers ................................ 131 9.4 Timeline of mapping technologies .................................................. 133 9.5 Timeline of map providers ................................................................ 133 9.6 Code snippets from own map production workflows .................. 134 9.6.1 Vector tiles workflow ................................................................. 134 9.6.2 Raster tiles workflow.................................................................. 137Heute sind zoombare Karten Alltag fĂŒr jeden Internetznutzer. Die Erstellung interaktiv zoombarer Karten ist allerdings wenig erforscht, was einen deutlichen Gegensatz zu ihrer aktuellen Bedeutung und NutzungshĂ€ufigkeit darstellt. Die Forschung in diesem Bereich ist also umso notwendiger. Steigende Datenmengen und grĂ¶ĂŸere Regionen, die von Karten abgedeckt werden sollen, unterstreichen den Forschungsbedarf umso mehr. Beispiele fĂŒr stetig wachsende Datenmengen sind Geodatenquellen wie OpenStreetMap aber auch freie amtliche GeodatensĂ€tze (OpenData), aber auch die zunehmende Zahl georeferenzierter Inhalte auf Internetplatformen wie Twitter oder Flickr zu nennen. Das Thema dieser Arbeit ist die Visualisierung eben dieser nutzergenerierten Geodaten mittels zoombarer Karten. DafĂŒr wird die Entwicklung der zugrundeliegenden Technologien ĂŒber die letzten zwei Jahr-zehnte und die damit verbundene Möglichkeiten vorgestellt. Weitere BeitrĂ€ge sind zwei neue Visualisierungsmethoden, die sich besonders fĂŒr die Darstellung von Punktdaten aus raumbezogenen nutzergenerierten Daten und georeferenzierte Daten aus Sozialen Netzwerken eignen. Ein Beitrag dieser Arbeit ist eine neue Visualisierungsmethode fĂŒr raumbezogene Informationen in Form von Punktgeometrien mit nominal skalierten Daten aus Sozialen Medien, wie beispielsweise Twitter oder Flickr. Typisch fĂŒr diese Daten ist eine hohe Anzahl von BeitrĂ€gen mit unterschiedlichen Kategorien. Wobei die BeitrĂ€ge, bedingt durch ihre schiere Menge und Ă€hnlicher Ei-genschaften, eher generisch als einzigartig sind. Ein Beitrag in den So-zia len Medien entspricht dabei einem Punkt mit einer bestimmten Katego-rie. Ein solcher Datensatz kann mit der neuen Methode der „micro diagrams“ in verschiedenen MaßstĂ€ben und Auflösungen visualisiert und analysiert werden. Dazu werden die Daten in kleine Gitterzellen aggregiert. Die Menge und Verteilung der ĂŒber die Kategorien aggregierten Punkte wird durch kleine Diagramme dargestellt, wobei die Farben die verschiedenen Kategorien visualisieren. Durch die geringere GrĂ¶ĂŸe der einzelnen Diagramme verschmelzen die kleinen Diagramme visuell, je nach der Verteilung der Farben fĂŒr die Kategorien. Bei genauerem Hinsehen ist die SchĂ€tzung der Menge der aggregierten Punkte ĂŒber die GrĂ¶ĂŸe der Diagramme die Menge und die Verteilung ĂŒber die Kategorien möglich. FĂŒr einzigartigere Punkte, die als Points of Interest (POI) angesehen werden, wird ein anderer Visualisierungsansatz vorgeschlagen, der auf einer Auswahlmethode basiert. Ziel ist es dabei lokal relevantere Punkte aus dem Datensatz zu identifizieren, die im Vergleich zu anderen Punkten in der Nachbarschaft des Punktes verglichen nach einem numerischen Attribut wichtiger sind. Die Methode ist von dem geographischen Prinzip der Dominanz von Bergen abgeleitet und wird „discrete isolation“ genannt. Es handelt sich dabei um die Distanz von einem Punkt zum nĂ€chsten mit einem höheren Attributwert. Durch die Verwendung dieses Maßes können lokal bedeutende Punkte leicht ausgewĂ€hlt werden, indem ein minimaler Abstand gewĂ€hlt und so rĂ€umlich gleichmĂ€ĂŸig verteilte Punkte aus dem Datensatz ausgewĂ€hlt werden. Die beiden neu vorgestellten Methoden werden in den Kontext der zoombaren Karten gestellt, indem exemplarische ArbeitsablĂ€ufe erstellt werden, die als Er-gebnis eine zoombare Karte liefern. Dazu werden die frei verfĂŒgbaren Beispiele zur Herstellung von weltweiten zoombaren Karten mit nutzergenerierten Geo-daten von OpenStreetMap, anhand der Kartenprojekte OpenMapTiles und O-penStreetMap Carto analysiert und in Arbeitsschritte gegliedert. Das Ergebnis ist ein wiederverwendbarer Arbeitsablauf zur Herstellung zoombarer Karten, ergĂ€nzt durch eine Auswahl von passender Software fĂŒr die einzelnen Arbeits-schritte. Dabei wird insbesondere auf die GeneralisierungsansĂ€tze in den Beispielprojekten eingegangen und diese anhand von Literatur in die kartographische Theorie eingeordnet. Zur Demonstration des Workflows wird je ein Raster Tiles Dienst fĂŒr die „micro diagrams“ und ein Vektor Tiles Dienst fĂŒr die „discrete isolation“ erstellt. Beide Dienste lassen sich mit einem aktuellen Webbrowser nutzen. Zusammenfassend ermöglichen diese neuen VisualisierungsansĂ€tze fĂŒr Punkt-daten aus VGI und LBSM eine bessere qualitative Visualisierung der neuen Geodaten. Die Analyse riesiger globaler DatensĂ€tze ist immer noch eine Herausforderung, aber die Erforschung und Analyse verborgener Muster in den Daten ist lohnend. Die Erstellung solcher Visualisierungen und die Produktion von Karten in verschiedenen MaßstĂ€ben ist eine komplexe Aufgabe. Die in dieser Arbeit vorgestellten ArbeitsablĂ€ufe und Werkzeuge erleichtern die Erstellung von Karten in globalem Maßstab.:1 Introduction 1 1.1 Motivation .................................................................................................. 3 1.2 Visualization of crowdsourced geodata on multiple scales ............ 5 1.2.1 Research objective 1: Visualization of point collections ......... 6 1.2.2 Research objective 2: Visualization of points of interest ......... 7 1.2.3 Research objective 3: Production of multiscale maps ............. 7 1.3 Reader’s guide ......................................................................................... 9 1.3.1 Structure ........................................................................................... 9 1.3.2 Related Publications ....................................................................... 9 1.3.3 Formatting and layout ................................................................. 10 1.3.4 Online examples ........................................................................... 10 2 Foundations of crowdsourced mapping on multiple scales 11 2.1 Types and properties of crowdsourced data .................................. 11 2.2 Currents trends in cartography ......................................................... 11 2.3 Definitions .............................................................................................. 12 2.3.1 VGI .................................................................................................. 12 2.3.2 LBSM .............................................................................................. 13 2.3.3 Space, place, and location......................................................... 13 2.4 Visualization approaches for crowdsourced geodata ................... 14 2.4.1 Review of publications and visualization approaches ........... 14 2.4.2 Conclusions from the review ...................................................... 15 2.4.3 Challenges mapping crowdsourced data ................................ 17 2.5 Technologies for serving multiscale maps ...................................... 17 2.5.1 Research about multiscale maps .............................................. 17 2.5.2 Web Mercator projection ............................................................ 18 2.5.3 Tiles and zoom levels .................................................................. 19 2.5.4 Raster tiles ..................................................................................... 21 2.5.5 Vector tiles .................................................................................... 23 2.5.6 Tiling as a principle ..................................................................... 25 3 Point collection visualization with categorized attributes 26 3.1 Target users and possible tasks ....................................................... 26 3.2 Example data ......................................................................................... 27 3.3 Visualization approaches .................................................................... 28 3.3.1 Common techniques .................................................................... 28 3.3.2 The micro diagram approach .................................................... 30 3.4 The micro diagram and its parameters ............................................ 33 3.4.1 Aggregating points into a regular structure ............................ 33 3.4.2 Visualizing the number of data points ...................................... 35 3.4.3 Grid and micro diagrams ............................................................ 36 3.4.4 Visualizing numerical proportions with diagrams .................. 37 3.4.5 Influence of color and color brightness ................................... 38 3.4.6 Interaction options with micro diagrams .................................. 39 3.5 Application and user-based evaluation ............................................ 39 3.5.1 Micro diagrams in a multiscale environment ........................... 39 3.5.2 The micro diagram user study ................................................... 41 3.5.3 Point collection vis

    Operational Research: methods and applications

    Get PDF
    This is the final version. Available on open access from Taylor & Francis via the DOI in this recordThroughout its history, Operational Research has evolved to include methods, models and algorithms that have been applied to a wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first summarises the up-to-date knowledge and provides an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion and used as a point of reference by a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes

    Operational research:methods and applications

    Get PDF
    Throughout its history, Operational Research has evolved to include a variety of methods, models and algorithms that have been applied to a diverse and wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first aims to summarise the up-to-date knowledge and provide an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion. It should be used as a point of reference or first-port-of-call for a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order
    • 

    corecore