Patrice Boursier

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.

Location-based spatial data management in navigation systems

We describe an embedded system for vehicle navigation. We use an Internet-based connection to download data stored on a distant server and a Java-enabled Web browser interface to visualize them locally. Data management is based on vehicle location. All data are transferred as the result of queries defined on the client side and executed on the data server. The request management on client side uses a data cache and takes into account spatial aspect of data and client location. 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. The vehicle is located by defining several map-matching algorithms to perform in real time integration of vehicle location in digital maps.

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-based vehicle localization

The development of wireless communications and the growing computational power of mobile devices reduces the difference between desktop and mobile computing environments. In this paper we present an embedded vehicle localization system which is developed on technologies commonly used in desktop applications. The architecture of our system is a client-server one. It is Web-based system. All data are presented to the user through a Web browser interface. They are processed locally by Java applets or on the server by Java applications. Data are accessed through common Internet connections: TCP/IP or higher level protocol like HTTP. Our system uses differential GPS for localization of vehicles and cellular phone for communication with data servers. It integrates the possibility to send differential GPS corrections through the Internet connection.

MASIR: A Multi-agent System for Real-Time Information Retrieval from Microblogs During Unexpected Events

Microblogs have proved their potential to attract people from all over the world to express voluntarily what is happening around them during unexpected events. However, retrieving relevant information from the huge amount of data shared in real time in these microblogs remain complex. This paper proposes a new system named MASIR for real-time information retrieval from microblogs during unexpected events. MASIR is based on a decentralized and collaborative multi-agent approach analyzing the profiles of users interested in a given event in order to detect the most prominent ones that have to be tracked in real time. Real time monitoring of these users enables a direct access to valuable fresh information. Our experiments shows that MASIR simplifies the real-time detection and tracking of the most prominent users by exploring both the old and fresh information shared during the event and outperforms the standard centrality measures by using a time-sensitive ranking model.

Predicted and Corrected Location Estimation of Mobile Nodes Based on the Combination of Kalman Filter and the Bayesian Decision Theory

The main objective of this research is to apply statistical location estimation techniques in cellular networks in order to calculate the precise location of the mobile node. Current research is focusing on the combination of Kalman filter and the Bayesian decision theory based location estimation. In this research basic four steps of Kalman filter are followed which are Estimation, Filtering, Prediction and Fusion. Estimation is done by using Receive Signal Strength (RSS), Available Signal Strength (ASS) and the Angle of Arrival (AOA). Filtering is done by calculating the average location and variation in values of location. Prediction is done by using the Bayesian decision theory. Fusion is done by combining the variances calculated in filtering step. Finally by combining the prediction and fusion results PCLEA (Predicted and Corrected Location Estimation Algorithm) is established. Timestamp is used for recursive step in kalman filter. The aim of this research is to minimize the dependence on the satellite based location estimation and increase its accuracy, efficiency and reliability.

Terrain/clutter based error calculation in location estimation of wireless nodes by using receive signal strength

This is a research with the main objective to investigate the error rate in the location estimation of a wireless node, by considering the error rate of different terrains/clutters. Radio waves behave differently in different terrains. When the transmitted signal propagates through different terrains, the terrain impairments affect the transmitted signal. Because of the noise addition, the received signal value differs from the transmitted signal value. For location estimation this received signal is used as a primary value for parameters calculation. If we do not consider terrain impairments then it will not give an accurate position of wireless node. Therefore it is required to investigate the signal to noise ratio and the error rate in different terrains. In this research paper, we divide the terrain in twelve different categories based on the error rate of terrains. We use C# program with WiFi (IEEE 802.11 b/g) setup to calculate the receive signal quality from 0 (zero) to 150 meters in different terrains for this experiment. We construct an error rate table (ERT) by comparing the ideal condition data with different terrains data, which helps to minimize the possible location area. This research helps to minimize location estimation error rate by considering the terrain impairments.

Integration of Heterogeneous Spatial Databases for Disaster Management

The response phase in a disaster case is often considered to be the most critical in terms of saving lives and dealing with irreversible damage. The timely provision of geospatial information is crucial in the decision-making process. Thus, there is a need for the integration of heterogeneous spatial databases which are inherently distributed and created under different projects by various organizations. The integration of all relevant data for timely decision making is a challenging task due to syntactic, schematic and semantic heterogeneity. This paper aims to propose a framework for the integration of heterogeneous spatial databases using novel approaches, such as web services and ontologies. We focus on providing solutions for the three levels of heterogeneity, in order to be able to interrogate the content of the different databases conveniently. Based on the proposed framework, we implemented a use case using heterogeneous data belonging to La Rochelle city in France.