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

Abstract

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. r

A critical evaluation of location based services and their potential

“…Dias et al (2004) outline the fully web-based architecture of the WebPark system operating in several European National Parks based on the use of a mini-webserver on the client device that communicates using http protocols, and which is extended for vector data using a Scalable Vector Graphics (SVG) plugin. Follin (2005) outlined how a client-server approach to mobile data management can be optimised using a multiresolution database to transmit increments to the client when needed for a scale change. Doyle et al (2005) developed personalised maps for mobile users using web technologies to avoid the user interface complexity of a proprietary interface.…”

View- and Scale-Based Progressive Transmission of Vector Data

“…To the author's knowledge only three works attempting such a fusion exist. These are the works of Ramos et al [16], Follin [8] and Li [13]. We now describe each of these approaches in turn and illustrate that one of the greatest challenges in implementing such a transmission strategy is maintaining topological equivalence with the original map.…”

“…No attempt is made to maintain topologically equivalence with the original map. Follin [8] proposes to transmit those features contained within a client view through the application of refinement techniques which are the inverse of generalization. It was demonstrated by Corcoran et al [4] that such an approach does not ensure topological equivalence.…”

Constrained set-up of the tGAP structure for progressive vector data transfer

“…Taking the example of a river network, Bo et al (2008) present a structure that is based on a changes accumulation model, which is used for progressive transfer. Bertolotto and Egenhofer (2001) and Follin et al (2005) generally express differences between different given vector maps by atomic generalisation and refinement operators. These include the merge operation of two areas, which is sufficient to model the differences in the example of Fig.…”