Knowledge revision in systems based on an informed tree search strategy : application to cartographic generalisation

Many real world problems can be expressed as optimisation problems. Solving this kind of problems means to find, among all possible solutions, the one that maximises an evaluation function. One approach to solve this kind of problem is to use an informed search strategy. The principle of this kind of strategy is to use problem-specific knowledge beyond the definition of the problem itself to find solutions more efficiently than with an uninformed strategy. This kind of strategy demands to define problem-specific knowledge (heuristics). The efficiency and the effectiveness of systems based on it directly depend on the used knowledge quality. Unfortunately, acquiring and maintaining such knowledge can be fastidious. The objective of the work presented in this paper is to propose an automatic knowledge revision approach for systems based on an informed tree search strategy. Our approach consists in analysing the system execution logs and revising knowledge based on these logs by modelling the revision problem as a knowledge space exploration problem. We present an experiment we carried out in an application domain where informed search strategies are often used: cartographic generalisation.Comment: Knowledge Revision; Problem Solving; Informed Tree Search Strategy; Cartographic Generalisation., Paris : France (2008

CartAGen: an Open Source Research Platform for Map Generalization

International audienceAutomatic map generalization is a complex task that is still a research problem and requires the development of research prototypes before being usable in productive map processes. In the meantime, reproducible research principles are becoming a standard. Publishing reproducible research means that researchers share their code and their data so that other researchers might be able to reproduce the published experiments, in order to check them, extend them, or compare them to their own experiments. Open source software is a key tool to share code and software, and CartAGen is the first open source research platform that tackles the overall map generalization problem: not only the building blocks that are generalization algorithms, but also methods to chain them, and spatial analysis tools necessary for data enrichment. This paper presents the CartAGen platform, its architecture and its components. The main component of the platform is the implementation of several multi-agent based models of the literature such as AGENT, CartACom, GAEL, CollaGen, or DIOGEN. The paper also explains and discusses different ways, as a researcher, to use or to contribute to CartAGen

Designing Multi-Scale Maps: Lessons Learned from Existing Practices

International audienceMapping applications display multi-scale maps where zooming in and out triggers the display of different maps at different scales. Multi-scale maps strongly augmented the potential uses of maps, compared to the traditional single-scaled paper maps. But the exploration of the multi-scale maps can be cognitively difficult for users because the content of the maps can be very different at different scales. This paper seeks to identify the factors in the design of map content and style that increase or decrease the exploration cognitive load, in order to improve multi-scales map design. We studied sixteen existing examples of multi-scale maps to identify these factors that influence a fluid zooming interaction. Several different analyses were conducted on these sixteen multiscale maps. We first conducted a guided visual exploration of the maps, and a detailed study of the scales of the maps, to identify general trends of good practices (e.g. the WMTS standard that defines zoom levels is widely used) and potential ways of improvement (e.g. a same map is often used at multiple successive zoom levels). Then, we focused on the visual complexity of the multi-scale maps by analyzing how it varies, continuously or not, across scales, using clutter measures, which showed a peak of complexity at zoom level 12 of the WMTS standard. Finally, we studied how buildings and roads are subject to abstraction changes across scales (e.g. at what zoom level individual buildings turn into built-up areas), which can be one of the causes of exploration difficulties. We identified some good practices to reduce the impact of abstraction changes, for instance by mixing different levels of abstraction in the same map.Les applications cartographiques actuelles affichent des cartes multi-échelles, dans lesquelles une interaction de zoom avant ou arrière déclenche l'affichage d'une nouvelle carte à plus grande ou plus petite échelle. Ces cartes multi-échelles permettent des utilisations beaucoup plus vastes et diverses que les traditionnelles cartes topographiques imprimées sur papier. Mais l'exploration interactive de ces cartes peut entrainer une charge cognitive assez lourde car le contenu des cartes peut varier très fortement entre les différentes échelles, et il devient difficile de se repérer. Cet article cherche à identifier les facteurs du design cartographique qui influent sur cette charge cognitive lors d'un changement d'échelle, avec pour objectif à long terme d'améliorer les pratiques de conception de cartes multi-échelles. Nous avons ainsi étudié seize exemples de cartes multi-échelles pour identifier les facteurs permettant d'influer sur la fluidité du zoom. Plusieurs analyses différentes ont été menées sur ces seize cartes. Nous avons d'abord réalisé une analyse visuelle de ces cartes selon divers critères, et une étude détaillée des différentes échelles utilisées, afin d'identifier des tendances (comme l'utilisation massive du standard WMTS), ou des pistes d'amélioration (par exemple, l'utilisation d'une même carte à plusieurs échelles parait sous-optimale). Nous avons ensuite mesuré la variation de complexité visuelle des cartes quand les échelles varient à l'aide de mesures de l'effet de ≪ clutter ≫ ce qui a notamment montré un pic de complexité pour les cartes présentées au niveau de zoom n∘12 du standard WMTS. Enfin, nous avons étudié les changements de niveau d'abstraction spécifiquement sur les thèmes ≪ bâti ≫ et ≪ routes ≫ (par exemple à quelle échelle la représentation des bâtiments individuels est remplacée par une représentation de l'aire urbaine), ce qui a permis de mettre en valeur une cause possible de ces difficultés d'exploration. Des bonnes pratiques ont été identifiées pour une meilleure transition entre les niveaux d'abstraction, notamment en les combinant dans une même carte à une échelle de transition

Assessing the Variation of Visual Complexity in Multi-Scale Maps with Clutter Measures

workshopInternational audienceMapping applications, where a multi-scale navigation is available, display multi-scale maps, i.e. a set of maps at different scales. Across scales, the map levels (Fig. 1) can present large differences in terms of representation, due to cartographic generalisation. In our research project [2], we assume that adding intermediate representations between existing map levels could be one way to reduce these differences and to enable smooth transitions while zooming. Inspired by the literature (§2.b), we believe that smooth zooming requires regular and small variations of map complexity across scales. In this paper, we present our experiments assessing clutter variation in existing multi-scale maps. This study seeks to identify if clutter variations may predict the perceived variation of visual complexity in multi-scale maps. After presenting some research works connected to our experiments (§2), the following sections address our research issues and study procedure (§3), then results analysis (§4). Lastly, we discuss the relevance of clutter measures for our project and presents our future work (§5)

Using Belief Theory to Diagnose Control Knowledge Quality. Application to cartographic generalisation

Both humans and artificial systems frequently use trial and error methods to problem solving. In order to be effective, this type of strategy implies having high quality control knowledge to guide the quest for the optimal solution. Unfortunately, this control knowledge is rarely perfect. Moreover, in artificial systems-as in humans-self-evaluation of one's own knowledge is often difficult. Yet, this self-evaluation can be very useful to manage knowledge and to determine when to revise it. The objective of our work is to propose an automated approach to evaluate the quality of control knowledge in artificial systems based on a specific trial and error strategy, namely the informed tree search strategy. Our revision approach consists in analysing the system's execution logs, and in using the belief theory to evaluate the global quality of the knowledge. We present a real-world industrial application in the form of an experiment using this approach in the domain of cartographic generalisation. Thus far, the results of using our approach have been encouraging.Comment: Best paper award, International Conference on Computing and Communication Technologies (IEEE-RIVF), Danang : Viet Nam (2009

Routes visualization: Automated placement of multiple route symbols along a physical network infrastructure

This paper tackles the representation of routes carried by a physical network infrastructure on a map. In particular, the paper examines the case where each route is represented by a separate colored linear symbol offset from the physical network segments and from other routes---as on public transit maps with bus routes offset from roads. In this study, the objective is to automate the placement of such route symbols while maximizing their legibility, especially at junctions. The problem is modeled as a constraint optimization problem. Legibility criteria are identified and formalized as constraints to optimize, while focusing on the case of hiking routes in a physical network composed of roads and pedestrian paths. Two solving methods are tested, based on backtracking and simulated annealing meta-heuristics respectively. Encouraging results obtained on real data are presented and discussed

Référentiel de compétences Bachelière et bachelier en soins infirmiers

Le bachelier en soins infirmiers est un professionnel polyvalent du secteur de la santé. Qualifié d’art infirmier, son métier est régi et protégé par divers arrêtés royaux. Le grade de bachelier en soins infirmiers peut donner accès au titre professionnel de praticien infirmier gradué tel que défini dans l’Arrêté royal n°78 du 10 novembre 1967 relatif à l’exercice de professions de soins de santé (MB du 14/11/1967). Exercer l’art infirmier demande des compétences professionnelles spécifiques, déterminées en cohérence avec les besoins de santé des populations et répondant aux exigences des décrets nationaux et des recommandations européennes dont la directive 2005/36/CE[1] relative à la reconnaissance des qualifications professionnelles. Différents travaux dont le projet CRESI (2006-2008) et le «Tuning Project for Nursing»[2], ont proposé des compétences pour l’infirmier(ère) en soins généraux au terme de la formation bachelière. En janvier 2011, le Conseil Général des Hautes Écoles (CGHE)[3] de la Fédération Wallonie-Bruxelles a proposé une description de la formation bachelière en soins infirmiers (Rapport d’activités CGHE 2010-2011)[4] qui amène le(la) futur(e) professionnel(le) à développer six compétences déclinées en capacités et une «posture réflexive». Ce référentiel de compétences HENALLUX de la bachelière et du bachelier en soins infirmiers (BSI) propose une déclinaison en acquis d’apprentissage[5] des six compétences et de leurs capacités. Ces acquis se fondent sur les descripteurs du niveau 6 du cadre européen des certifications (CEC)[6] indiquant «les acquis de l’éducation et de la formation attendus d’une certification de niveau 6 quel que soit le système de certification», dans le but d’améliorer la transparence des qualifications et de favoriser la mobilité. Le CEC fait notamment référence aux compétences en termes de prise de responsabilité et d’autonomie : • gérer des activités ou des projets techniques ou professionnels complexes, incluant des responsabilités au niveau de la prise de décisions dans des contextes professionnels ou d’études imprévisibles ; • prendre des responsabilités en matière de développement professionnel individuel et collectif

Automated Generalisation Results Using the Agent-Based Platform CartAGen

International audienc

Towards an Ontology of Spatial Relations and Relational Constraints: The Need for Constraints and Spatial Relations Ontology

workshopInternational audienc

Référencement spatial indirect: modélisation à base de relations et d’objets spatiaux vagues

International audienceThis paper proposes a methodology for transforming a relative position description expressed in an indirect repository into an absolute position in a direct repository. This problem requires the formalization of relative location elements, here in the form of a triplet model, which is used as a basis for the transformation from relative to absolute position and the questioning on how the imperfection of the natural language in the modeling process can be taken into account. We propose to use fuzzy spatial objects and we will compare their implementations to identify the most appropriate approach to our context.Cet article propose une méthodologie destinée à transformer une description de position exprimée dans un référentiel indirect en une position absolue dans un référentiel direct.Cette problématique nécessite une formalisation des éléments de localisation relatifs, ici sous la forme d’un modèle en triplets, utilisés comme base de référencement et un questionnement sur la prise en compte de l’imperfection du langage naturel dans le processus de modélisation. Nous proposons de faire appel aux objets spatiaux flous et nous comparerons leurs implémentations afin d’identifier l’approche la plus adaptée au contexte du secours en montagne