SIG ChAOS : Représentation (La) de l'environnement sonore urbain à l'aide d'un système d'information géographique, Tome 1 et 2

Cette recherche a pour but de développer la représentation qualitative des phénomènes sonores urbains dans le sens d'une exploitation opérationnelle, en explorant les possibilités d'un Système d'Information Géographique (SIG)

Visualizing Integration Uncertainty Enhances User's Choice in Multi-Providers Integrated Maps

International audienceThis poster presents an experiment to assess how representation of uncertainty of cartographic integration of multi-providers services is used by end-users

Dictionary Compression in Point Cloud Data Management

Nowadays, massive amounts of point cloud data can be collected thanks to advances in data acquisition and processing technologies like dense image matching and airborne LiDAR (Light Detection and Ranging) scanning. With the increase in volume and precision, point cloud data offers a useful source of information for natural resource management, urban planning, self-driving cars and more. At the same time, the scale at which point cloud data is produced, introduces management challenges: it is important to achieve efficiency both in terms of querying performance and space requirements. Traditional file-based solutions to point cloud management offer space efficiency, however, cannot scale to such massive data and provide the same declarative power as a database management system (DBMS). In this paper, we propose a time- and space-efficient solution to storing and managing point cloud data in main memory column-store DBMS. Our solution, Space-Filling Curve Dictionary-Based Compression (SFC-DBC), employs dictionary-based compression in the spatial data management domain and enhances it with indexing capabilities by using space-filling curves. It does so by constructing the space-filling curve over a compressed, artificially introduced 3D dictionary space. Consequently, SFC-DBC significantly optimizes query execution, and yet it does not require additional storage resources, compared to traditional dictionary-based compression. With respect to space-filling curve-based approaches, it minimizes storage footprint and increases resilience to skew. As a proof of concept, we develop and evaluate our approach as a research prototype in the context of SAP HANA. SFC-DBC outperforms other dictionary-based compression schemes by up to 61% in terms of space and up to 9.4x in terms of query performance

An efficient semiparametric maxima estimator of the extremal index

The extremal index $\theta$, a measure of the degree of local dependence in the extremes of a stationary process, plays an important role in extreme value analyses. We estimate $\theta$ semiparametrically, using the relationship between the distribution of block maxima and the marginal distribution of a process to define a semiparametric model. We show that these semiparametric estimators are simpler and substantially more efficient than their parametric counterparts. We seek to improve efficiency further using maxima over sliding blocks. A simulation study shows that the semiparametric estimators are competitive with the leading estimators. An application to sea-surge heights combines inferences about $\theta$ with a standard extreme value analysis of block maxima to estimate marginal quantiles.Comment: 17 pages, 7 figures. Minor edits made to version 1 prior to journal publication. The final publication is available at Springer via http://dx.doi.org/10.1007/s10687-015-0221-

Browsing Semantics in Context-Aware Mobile Hypermedia

Mobile hypermedia applications combine the well-known advantages of the navigational paradigm of the Web with the capabilities of location-aware software. However, there are some subtleties to integrate them synergistically. In this paper we analyze different aspects related with navigation semantics in mobile hypermedia; in particular we discuss the problems which arise in the use of the familiar backward and forward operations when physical navigation in the real world is involved. Using a motivating example, we present a simple model to handle physical and digital navigation in a cohesive way. We also describe a modular implementation of our ideas in an architecture which support context-aware services.Publicado en: Meersman R., Tari Z., Herrero P. (eds) On the Move to Meaningful Internet Systems 2007: OTM 2007 Workshops. OTM 2007. Lecture Notes in Computer Science, vol 4805. Springer, Berlin, Heidelber

A Primer of Picture-Aided Navigation in Mobile Systems

The goal of this paper is to present a new concept regarding the way of explaining itineraries based on pictures in mobile systems. Instead of presenting a map, or a list of words, an original method is proposed based on a picture database and handheld devices. Knowing the exact position of the user, the system will sent him regularly pictures of the way where to go. This system is especially targeted not for drivers but for pedestrians essentially in tourist cities. In order to reach this objective, pictures were taken along each street both ways. Thus, a picture database was built for which the more common query is to compute the minimum path for going from one place to another. The result format is initially presented as a sequence of nodes and edges; then this sequence is transformed into a sequence of pictures. Those pictures are then sent to the user according to his position and his pace. In order to help the user, the pictures are decorated with arrows.This presentation is based on two prototypes made within a French-Argentinean collaboration.Trabajo publicado en Lecture Notes in Geoinformation and Cartography book seriesLaboratorio de Investigación y Formación en Informática Avanzad

Visual Summaries of Geographic Databases

National audienceFor several applications, it is interesting to have an idea of database contents. For instance in geo-marketing, a decision-maker could be interested in knowing the places where his products are not well sold. In other words, the summary of a database must include only the important items.The goal of this paper will be to present an international project aiming at generating visual summaries of geographic databases based on chorems. From years, chorems – as schematized representations of territories invented by a geographer named Brunet – are used to represent the more salient aspects of a territory. But in this methodology, the designer is supposed to know everything and to propose a schema. In contrast, in our project, the starting point is a geographic database representing information over a territory for which one wants to generate a drawing emphasizing only the salient aspects called patterns. So, two main problems exist, first to extract the salient patterns from spatial data mining, and the second visualizing the results after having done both a geometric generalization of the territory boundaries, and a semantic generalization of the contents.This paper will first present the problems of discovering patterns and selecting the more important ones (5 2). Then, we will explain how to make the geometric and semantic generalizations. After having presented a model of patterns, we will present the ChorML language used for both for storing and visualizing them

Visual Summaries of Geographic Databases

National audienceFor several applications, it is interesting to have an idea of database contents. For instance in geo-marketing, a decision-maker could be interested in knowing the places where his products are not well sold. In other words, the summary of a database must include only the important items.The goal of this paper will be to present an international project aiming at generating visual summaries of geographic databases based on chorems. From years, chorems – as schematized representations of territories invented by a geographer named Brunet – are used to represent the more salient aspects of a territory. But in this methodology, the designer is supposed to know everything and to propose a schema. In contrast, in our project, the starting point is a geographic database representing information over a territory for which one wants to generate a drawing emphasizing only the salient aspects called patterns. So, two main problems exist, first to extract the salient patterns from spatial data mining, and the second visualizing the results after having done both a geometric generalization of the territory boundaries, and a semantic generalization of the contents.This paper will first present the problems of discovering patterns and selecting the more important ones (5 2). Then, we will explain how to make the geometric and semantic generalizations. After having presented a model of patterns, we will present the ChorML language used for both for storing and visualizing them

Systèmes d'information pour la participation des citoyens aux décisions relatives à l'aménagement du territoire

National audienc