471 research outputs found

    Automated processing for map generalization using web services

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    In map generalization various operators are applied to the features of a map in order to maintain and improve the legibility of the map after the scale has been changed. These operators must be applied in the proper sequence and the quality of the results must be continuously evaluated. Cartographic constraints can be used to define the conditions that have to be met in order to make a map legible and compliant to the user needs. The combinatorial optimization approaches shown in this paper use cartographic constraints to control and restrict the selection and application of a variety of different independent generalization operators into an optimal sequence. Different optimization techniques including hill climbing, simulated annealing and genetic deep search are presented and evaluated experimentally by the example of the generalization of buildings in blocks. All algorithms used in this paper have been implemented in a web services framework. This allows the use of distributed and parallel processing in order to speed up the search for optimized generalization operator sequence

    A multi-agent system for on-the-fly web map generation and spatial conflict resolution

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    RĂ©sumĂ© Internet est devenu un moyen de diffusion de l’information gĂ©ographique par excellence. Il offre de plus en plus de services cartographiques accessibles par des milliers d’internautes Ă  travers le monde. Cependant, la qualitĂ© de ces services doit ĂȘtre amĂ©liorĂ©e, principalement en matiĂšre de personnalisation. A cette fin, il est important que la carte gĂ©nĂ©rĂ©e corresponde autant que possible aux besoins, aux prĂ©fĂ©rences et au contexte de l’utilisateur. Ce but peut ĂȘtre atteint en appliquant les transformations appropriĂ©es, en temps rĂ©el, aux objets de l’espace Ă  chaque cycle de gĂ©nĂ©ration de la carte. L’un des dĂ©fis majeurs de la gĂ©nĂ©ration d’une carte Ă  la volĂ©e est la rĂ©solution des conflits spatiaux qui apparaissent entre les objets, essentiellement Ă  cause de l’espace rĂ©duit des Ă©crans d’affichage. Dans cette thĂšse, nous proposons une nouvelle approche basĂ©e sur la mise en Ɠuvre d’un systĂšme multiagent pour la gĂ©nĂ©ration Ă  la volĂ©e des cartes et la rĂ©solution des conflits spatiaux. Cette approche est basĂ©e sur l’utilisation de la reprĂ©sentation multiple et la gĂ©nĂ©ralisation cartographique. Elle rĂ©sout les conflits spatiaux et gĂ©nĂšre les cartes demandĂ©es selon une stratĂ©gie innovatrice : la gĂ©nĂ©ration progressive des cartes par couches d’intĂ©rĂȘt. Chaque couche d’intĂ©rĂȘt contient tous les objets ayant le mĂȘme degrĂ© d’importance pour l’utilisateur. Ce contenu est dĂ©terminĂ© Ă  la volĂ©e au dĂ©but du processus de gĂ©nĂ©ration de la carte demandĂ©e. Notre approche multiagent gĂ©nĂšre et transfĂšre cette carte suivant un mode parallĂšle. En effet, une fois une couche d’intĂ©rĂȘt gĂ©nĂ©rĂ©e, elle est transmise Ă  l’utilisateur. Dans le but de rĂ©soudre les conflits spatiaux, et par la mĂȘme occasion gĂ©nĂ©rer la carte demandĂ©e, nous affectons un agent logiciel Ă  chaque objet de l’espace. Les agents entrent ensuite en compĂ©tition pour l’occupation de l’espace disponible. Cette compĂ©tition est basĂ©e sur un ensemble de prioritĂ©s qui correspondent aux diffĂ©rents degrĂ©s d’importance des objets pour l’utilisateur. Durant la rĂ©solution des conflits, les agents prennent en considĂ©ration les besoins et les prĂ©fĂ©rences de l’utilisateur afin d’amĂ©liorer la personnalisation de la carte. Ils amĂ©liorent la lisibilitĂ© des objets importants et utilisent des symboles qui pourraient aider l’utilisateur Ă  mieux comprendre l’espace gĂ©ographique. Le processus de gĂ©nĂ©ration de la carte peut ĂȘtre interrompu en tout temps par l’utilisateur lorsque les donnĂ©es dĂ©jĂ  transmises rĂ©pondent Ă  ses besoins. Dans ce cas, son temps d’attente est rĂ©duit, Ă©tant donnĂ© qu’il n’a pas Ă  attendre la gĂ©nĂ©ration du reste de la carte. Afin d’illustrer notre approche, nous l’appliquons au contexte de la cartographie sur le web ainsi qu’au contexte de la cartographie mobile. Dans ces deux contextes, nous catĂ©gorisons nos donnĂ©es, qui concernent la ville de QuĂ©bec, en quatre couches d’intĂ©rĂȘt contenant les objets explicitement demandĂ©s par l’utilisateur, les objets repĂšres, le rĂ©seau routier et les objets ordinaires qui n’ont aucune importance particuliĂšre pour l’utilisateur. Notre systĂšme multiagent vise Ă  rĂ©soudre certains problĂšmes liĂ©s Ă  la gĂ©nĂ©ration Ă  la volĂ©e des cartes web. Ces problĂšmes sont les suivants : 1. Comment adapter le contenu des cartes, Ă  la volĂ©e, aux besoins des utilisateurs ? 2. Comment rĂ©soudre les conflits spatiaux de maniĂšre Ă  amĂ©liorer la lisibilitĂ© de la carte tout en prenant en considĂ©ration les besoins de l’utilisateur ? 3. Comment accĂ©lĂ©rer la gĂ©nĂ©ration et le transfert des donnĂ©es aux utilisateurs ? Les principales contributions de cette thĂšse sont : 1. La rĂ©solution des conflits spatiaux en utilisant les systĂšmes multiagent, la gĂ©nĂ©ralisation cartographique et la reprĂ©sentation multiple. 2. La gĂ©nĂ©ration des cartes dans un contexte web et dans un contexte mobile, Ă  la volĂ©e, en utilisant les systĂšmes multiagent, la gĂ©nĂ©ralisation cartographique et la reprĂ©sentation multiple. 3. L’adaptation des contenus des cartes, en temps rĂ©el, aux besoins de l’utilisateur Ă  la source (durant la premiĂšre gĂ©nĂ©ration de la carte). 4. Une nouvelle modĂ©lisation de l’espace gĂ©ographique basĂ©e sur une architecture multi-couches du systĂšme multiagent. 5. Une approche de gĂ©nĂ©ration progressive des cartes basĂ©e sur les couches d’intĂ©rĂȘt. 6. La gĂ©nĂ©ration et le transfert, en parallĂšle, des cartes aux utilisateurs, dans les contextes web et mobile.Abstract Internet is a fast growing medium to get and disseminate geospatial information. It provides more and more web mapping services accessible by thousands of users worldwide. However, the quality of these services needs to be improved, especially in term of personalization. In order to increase map flexibility, it is important that the map corresponds as much as possible to the user’s needs, preferences and context. This may be possible by applying the suitable transformations, in real-time, to spatial objects at each map generation cycle. An underlying challenge of such on-the-fly map generation is to solve spatial conflicts that may appear between objects especially due to lack of space on display screens. In this dissertation, we propose a multiagent-based approach to address the problems of on-the-fly web map generation and spatial conflict resolution. The approach is based upon the use of multiple representation and cartographic generalization. It solves conflicts and generates maps according to our innovative progressive map generation by layers of interest approach. A layer of interest contains objects that have the same importance to the user. This content, which depends on the user’s needs and the map’s context of use, is determined on-the-fly. Our multiagent-based approach generates and transfers data of the required map in parallel. As soon as a given layer of interest is generated, it is transmitted to the user. In order to generate a given map and solve spatial conflicts, we assign a software agent to every spatial object. Then, the agents compete for space occupation. This competition is driven by a set of priorities corresponding to the importance of objects for the user. During processing, agents take into account users’ needs and preferences in order to improve the personalization of the final map. They emphasize important objects by improving their legibility and using symbols in order to help the user to better understand the geographic space. Since the user can stop the map generation process whenever he finds the required information from the amount of data already transferred, his waiting delays are reduced. In order to illustrate our approach, we apply it to the context of tourist web and mobile mapping applications. In these contexts, we propose to categorize data into four layers of interest containing: explicitly required objects, landmark objects, road network and ordinary objects which do not have any specific importance for the user. In this dissertation, our multiagent system aims at solving the following problems related to on-the-fly web mapping applications: 1. How can we adapt the contents of maps to users’ needs on-the-fly? 2. How can we solve spatial conflicts in order to improve the legibility of maps while taking into account users’ needs? 3. How can we speed up data generation and transfer to users? The main contributions of this thesis are: 1. The resolution of spatial conflicts using multiagent systems, cartographic generalization and multiple representation. 2. The generation of web and mobile maps, on-the-fly, using multiagent systems, cartographic generalization and multiple representation. 3. The real-time adaptation of maps’ contents to users’ needs at the source (during the first generation of the map). 4. A new modeling of the geographic space based upon a multi-layers multiagent system architecture. 5. A progressive map generation approach by layers of interest. 6. The generation and transfer of web and mobile maps at the same time to users

    A genetic algorithm for tributary selection with consideration of multiple factors

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    Drainage systems are important components in cartography and Geographic Information Systems (GIS), and achieve different drainage patterns based on the form and texture of their network of stream channels and tributaries due to local topography and subsurface geology. The drainage pattern can reflect the geographical characteristics of a river network to a certain extent. To preserve the drainage pattern during the generalization process, this article proposes a solution to deal with many factors, such as the tributary length and the order in river tributary selection. This leads to a multi-objective optimization problem solved with a Genetic Algorithm. In the multi-objective model, different weights are used to aggregate all objective functions into a fitness function. The method is applied on a case study to evaluate the importance of each factor for different types of drainage and results are compared with a manually generalized network. The result can be controlled by assigning different weights to the factors. From this work, different weight settings according to drainage patterns are proposed for the river network generalization

    Cartographic modelling for automated map generation

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    Family names as indicators of Britain’s changing regional geography

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    In recent years the geography of surnames has become increasingly researched in genetics, epidemiology, linguistics and geography. Surnames provide a useful data source for the analysis of population structure, migrations, genetic relationships and levels of cultural diffusion and interaction between communities. The Worldnames database (www.publicprofiler.org/worldnames) of 300 million people from 26 countries georeferenced in many cases to the equivalent of UK Postcode level provides a rich source of surname data. This work has focused on the UK component of this dataset, that is the 2001 Enhanced Electoral Role, georeferenced to Output Area level. Exploratory analysis of the distribution of surnames across the UK shows that clear regions exist, such as Cornwall, Central Wales and Scotland, in agreement with anecdotal evidence. This study is concerned with applying a wide range of methods to the UK dataset to test their sensitivity and consistency to surname regions. Methods used thus far are hierarchical and non-hierarchical clustering, barrier algorithms, such as the Monmonier Algorithm, and Multidimensional Scaling. These, to varying degrees, have highlighted the regionality of UK surnames and provide strong foundations to future work and refinement in the UK context. Establishing a firm methodology has enabled comparisons to be made with data from the Great British 1881 census, developing insights into population movements from within and outside Great Britain

    Automated Pattern Detection and Generalization of Building Groups

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    This dissertation focuses on the topic of building group generalization by considering the detection of building patterns. Generalization is an important research field in cartography, which is part of map production and the basis for the derivation of multiple representation. As one of the most important features on map, buildings occupy large amount of map space and normally have complex shape and spatial distribution, which leads to that the generalization of buildings has long been an important and challenging task. For social, architectural and geographical reasons, the buildings were built with some special rules which forms different building patterns. Building patterns are crucial structures which should be carefully considered during graphical representation and generalization. Although people can effortlessly perceive these patterns, however, building patterns are not explicitly described in building datasets. Therefore, to better support the subsequent generalization process, it is important to automatically recognize building patterns. The objective of this dissertation is to develop effective methods to detect building patterns from building groups. Based on the identified patterns, some generalization methods are proposed to fulfill the task of building generalization. The main contribution of the dissertation is described as the following five aspects: (1) The terminology and concept of building pattern has been clearly explained; a detailed and relative complete typology of building patterns has been proposed by summarizing the previous researches as well as extending by the author; (2) A stroke-mesh based method has been developed to group buildings and detect different patterns from the building groups; (3) Through the analogy between line simplification and linear building group typification, a stroke simplification based typification method has been developed aiming at solving the generalization of building groups with linear patterns; (4) A mesh-based typification method has been developed for the generalization of the building groups with grid patterns; (5) A method of extracting hierarchical skeleton structures from discrete buildings have been proposed. The extracted hierarchical skeleton structures are regarded as the representations of the global shape of the entire region, which is used to control the generalization process. With the above methods, the building patterns are detected from the building groups and the generalization of building groups are executed based on the patterns. In addition, the thesis has also discussed the drawbacks of the methods and gave the potential solutions.:Abstract I Kurzfassung III Contents V List of Figures IX List of Tables XIII List of Abbreviations XIV Chapter 1 Introduction 1 1.1 Background and motivation 1 1.1.1 Cartographic generalization 1 1.1.2 Urban building and building patterns 1 1.1.3 Building generalization 3 1.1.4 Hierarchical property in geographical objects 3 1.2 Research objectives 4 1.3 Study area 5 1.4 Thesis structure 6 Chapter 2 State of the Art 8 2.1 Operators for building generalization 8 2.1.1 Selection 9 2.1.2 Aggregation 9 2.1.3 Simplification 10 2.1.4 Displacement 10 2.2 Researches of building grouping and pattern detection 11 2.2.1 Building grouping 11 2.2.2 Pattern detection 12 2.2.3 Problem analysis . 14 2.3 Researches of building typification 14 2.3.1 Global typification 15 2.3.2 Local typification 15 2.3.3 Comparison analysis 16 2.3.4 Problem analysis 17 2.4 Summary 17 Chapter 3 Using stroke and mesh to recognize building group patterns 18 3.1 Abstract 19 3.2 Introduction 19 3.3 Literature review 20 3.4 Building pattern typology and study area 22 3.4.1 Building pattern typology 22 3.4.2 Study area 24 3.5 Methodology 25 3.5.1 Generating and refining proximity graph 25 3.5.2 Generating stroke and mesh 29 3.5.3 Building pattern recognition 31 3.6 Experiments 33 3.6.1 Data derivation and test framework 33 3.6.2 Pattern recognition results 35 3.6.3 Evaluation 39 3.7 Discussion 40 3.7.1 Adaptation of parameters 40 3.7.2 Ambiguity of building patterns 44 3.7.3 Advantage and Limitation 45 3.8 Conclusion 46 Chapter 4 A typification method for linear building groups based on stroke simplification 47 4.1 Abstract 48 4.2 Introduction 48 4.3 Detection of linear building groups 50 4.3.1 Stroke-based detection method 50 4.3.2 Distinguishing collinear and curvilinear patterns 53 4.4 Typification method 55 4.4.1 Analogy of building typification and line simplification 55 4.4.2 Stroke generation 56 4.4.3 Stroke simplification 57 4.5 Representation of newly typified buildings 60 4.6 Experiment 63 4.6.1 Linear building group detection 63 4.6.2 Typification results 65 4.7 Discussion 66 4.7.1 Comparison of reallocating remained nodes 66 4.7.2 Comparison with classic line simplification method 67 4.7.3 Advantage 69 4.7.4 Further improvement 71 4.8 Conclusion 71 Chapter 5 A mesh-based typification method for building groups with grid patterns 73 5.1 Abstract 74 5.2 Introduction 74 5.3 Related work 75 5.4 Methodology of mesh-based typification 78 5.4.1 Grid pattern classification 78 5.4.2 Mesh generation 79 5.4.3 Triangular mesh elimination 80 5.4.4 Number and positioning of typified buildings 82 5.4.5 Representation of typified buildings 83 5.4.6 Resizing Newly Typified Buildings 85 5.5 Experiments 86 5.5.1 Data derivation 86 5.5.2 Typification results and evaluation 87 5.5.3 Comparison with official map 91 5.6 Discussion 92 5.6.1 Advantages 92 5.6.2 Further improvements 93 5.7 Conclusion 94 Chapter 6 Hierarchical extraction of skeleton structures from discrete buildings 95 6.1 Abstract 96 6.2 Introduction 96 6.3 Related work 97 6.4 Study area 99 6.5 Hierarchical extraction of skeleton structures 100 6.5.1 Proximity Graph Network (PGN) of buildings 100 6.5.2 Centrality analysis of proximity graph network 103 6.5.3 Hierarchical skeleton structures of buildings 108 6.6 Generalization application 111 6.7 Experiment and discussion 114 6.7.1 Data statement 114 6.7.2 Experimental results 115 6.7.3 Discussion 118 6.8 Conclusions 120 Chapter 7 Discussion 121 7.1 Revisiting the research problems 121 7.2 Evaluation of the presented methodology 123 7.2.1 Strengths 123 7.2.2 Limitations 125 Chapter 8 Conclusions 127 8.1 Main contributions 127 8.2 Outlook 128 8.3 Final thoughts 131 Bibliography 132 Acknowledgements 142 Publications 14

    Introduction of loose ribbons in geographic information system

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    886-898In a geographic information system, we use principally many models, such as points, polylines and regions to represent spatial objects. But, usually, lines represent linear objects that have a width, whereas from a mathematical point of view, lines have no width. To solve this paradox, in previous papers, the notion of rectilinear lines was replaced by rectangular ribbons. The rectangular ribbon was used to represent longish objects such as streets, roads and rivers. However, the problems come from their mathematical modeling because in reality, rivers and roads can have irregular widths and measurement errors must be taken into account. So, not all longish objects have rectangular shapes, but they can have loose ones. To solve this problem, the concept of a loose ribbon need be developed. In this paper, we address the eventual mutation of the topological relations between loose ribbons into other topological relations, according to certain criteria, when downscaling
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