Frédéric Bertrand

Multi-resolution extension for transmission of geodata in a mobile context

A solution is proposed for the management of multi-resolution vector data in a mobile spatial information visualization system. The client-server architecture and the models of data and transfer of the system are presented first. The aim of this system is to reduce data exchanged between client and server by reusing data already present on the client side. Then, an extension of this system to multi-resolution data is proposed. Our solution is based on the use of increments in a multi-scale database. A database architecture where data sets for different predefined scales are precomputed and stored on the server side is adopted. In this model, each object representing the same real world entities at different levels of detail has to be linked beforehand. Increments correspond to the difference between two datasets with different levels of detail. They are transmitted in order to increase (or decrease) the detail to the client upon request. They include generalization and refinement operators allowing transitions between the different levels. Finally, a framework suited to the transfer of multi-resolution data in a mobile context is presented. This allows reuse of data locally available at different levels of detail and, in this way, reduces the amount of data transferred between client and server.

Integrating GPS data within embedded Internet GIS

In this paper we investigate the development of an embedded and mobile geographic information system. Its main characteristics concern the possibility to access various information sources and to provide the basic functionalities of a navigation system, e.g. positioning. This system uses a differential Global Positioning System (GPS) device to acquire the position of a mobile (e.g. vehicle). A cellular phone with an Internet based connection permits to access distant data sources and to transfer data between the components of the system. A Web browser and a Java applet are used for data integration and visualization. As it is used in the context of a mobile application, the basic software component in the architecture of our system is a local embedded server. It ensures real time access to local GPS data, but also to multimedia and spatially referenced data which are stored on distant servers. We also present some results of practical experiments that have been carried out with this system embedded in a vehicle.

Accessing to spatial data in mobile environment

We describe the data management principles on which data processing is based in an embedded navigation system. We study this management in the framework of a Web-based navigation and spatial data visualization. We use an Internet-based connection to download the data located on a distant data server and a Web browser interface to process and to visualize them locally. All data are transferred as the result of queries defined on the client side and executed on the data server. The data management on the client side uses a data cache and takes into account the spatial aspect of data. It performs a test for semantic inclusion of results of queries and reuses already available data. We also introduce spatial query restrictions in order to reduce the selected data only to the data set relevant to the actual location of the mobile user. Restriction and semantic caching of queries allows us to reduce the amount of data transferred between a mobile client and a data server.

Client-server architecture for accessing multimedia and geographic databases within embedded systems

We present a software architecture that is dedicated to the development of an information system embedded in a vehicle allowing access to multimedia and geographic databases. This system provides some functionality of a navigation system and uses a Global Positioning System for recognizing the position of the vehicle. The client-server architecture allows communication between the components of the system, as well as access to various information sources. Communications are based on the use of a cellular phone and Internet connection. Web browser and Java applets are used for information presentation and processing. The combined use of embedded local server and distant servers is one of the main characteristics of the system.

Web architecture for monitoring and visualizing mobile objects in maritime contexts

Recent advances in telecommunication and positioning systems, web and wireless architectures offer new perspectives and challenges to the management and visualization of mobile and geo-referenced objects. Amongst many research challenges still opened, the development of integrated sensorbased architectures necessary to the integration of mobile data has been often neglected. Real-time integration of sensor-based data, their management within a distributed system, and diffusion to different levels of services and interfaces to what should be considered as a collaborative web GIS constitutes the objective of the research presented in this paper. This paper introduces a modular and experimental web GIS framework applied to maritime navigation, and where mobile objects behave in a maritime environment. Different levels of services are developed, including a web-based wireless access and interface to a traffic monitoring application.

Rewriting Queries by Means of Model Transformations from SPARQL to OQL and Vice-Versa

Implementing language translation is one of the main topics within the model to model transformation area. Nevertheless, a majority of solutions promoted by model driven engineering tools focus on transformations related to modeling languages. In this paper, we address query rewriting by means of model transformations. This study has been carried out within the context of implementing an object ontology mapping tool, which could enable bridging object oriented applications and RDF data sources. This approach allows querying RDF data sources via an object oriented query which is automatically rewritten in SPARQL (RDF query language) in order to access RDF data. Hence, the developer can freely focus upon the sole application object model. In this paper, we also present with solutions for translating SPARQL queries into object oriented queries, thus allowing the implementation of SPARQL endpoints for object oriented applications.

Applying Semantic Web Technologies for Improving the Visibility of Tourism Data

Tourism industry is an extremely information-intensive, complex and dynamic activity. It can benefit from semantic Web technologies, due to the significant heterogeneity of information sources and the high volume of on-line data. The management of semantically diverse annotated tourism data is facilitated by ontologies that provide methods and standards, which allow flexibility and more intelligent access to on-line data. This paper provides a description of some of the early results of the Tourinflux project which aims to apply semantic Web technologies to support tourist actors in effectively finding and publishing information on the Web.

Temporal knowledge acquisition and modeling

The objectives of this paper are to present, describe, and explain the foundations and the functionalities of a temporal knowledge acquisition and modeling solution workflow, which aims at acquiring temporal knowledge from texts in order to populate a constrained object model. We are using several models for temporal data, one of which is generic and employed as a pivot model between a linguistic representation and a calendar representation. The approach we propose is generic and has been tested against a real use case, in which input data is made of temporal properties defining when a given location (a theater, a restaurant, a shopping center, etc.) is open or closed. Most expressions entered are expressed in intension. Our models provide a core support to the system that linguistically analyses data entries, transforms them into extensive calendar information and allow users to control the quality of the systems interpretation.

Location-and temporal-based services for nature-society interaction regulation

With the surge of mobile devices and applications, knowledge base browsing and querying facilities must be adapted to new kinds of users and services. Space and time databases are concerned and as such are the subject of this article. Within a mobile context, data retrieval services must take the location of the call into consideration as regards space and time, insofar many pieces of information do depend on ‘where’ and ‘when’ constraints. We present here with a general object model dedicated to specifying time properties. The novel aspects of our proposal consist of three main points. First, the temporal object model stands as a pivot model, and all the more leverages interoperability between software applications, since it extends common standards, such as ISO 19108 and iCalendar. Second, we accompany the object model with a formal grammar close to natural languages, which helps end users in managing and checking temporal object instances. Finally, our proposal focuses on intensional temporal expressions instead of extensional sets of concrete calendar dates. This allows to express semantic aspects – namely for periodic (cyclic) events – which remain hidden and not computable when only a series of dates are given. We evoke two kinds of applications for which our model is beneficial; one concerns services called by human users and the other addresses calls placed by software agents e.g. in a multi-agent system for instance within a simulation context.

Gestion de masses de données au sein de bases de données capteurs

Les systemes a base de capteurs sont de plus en plus frequemment utilises pour de nombreuses applications comme la gestion de flottes de vehicules, la surveillance de trafic ou encore la surveillance de phenomenes environnementaux et urbains. Les donnees acquises par ces capteurs sont localisees et datees. Elles sont employees dans des applications de nature diverse gerant de grandes masses de donnees spatio-temporelles en temps reel et differe selon les besoins. L’objectif de cet article est de presenter la problematique, et de fournir quelques elements de reponse aux problemes scientifiques identifies. Apres la presentation d’applications pertinentes et exploitables, une liste des verrous scientifiques est exposee. Des elements de reponse sont ensuite detailles. Ces reflexions et travaux sont issus de membres des equipes de recherche collaborant au sein de l’axe « Reactivite, Mobilite et Temps Reel » et du GT « Services Localises » du GDR 2340 Sigma.