A NEW FLOWLINE FOR THE FRENCH TOPOGRAPHIC MAPS IN I.G.N.

A. Braun, X. Halbecq, F. Lecordix, J.-M. Le Gallinc, F. Prigen

I.G.N. France

arnaud.braun@ign.fr

The French National Mapping Agency (IGN) aims at building a new flowline for its 1:25.000 and 1:50.000 topographic map series. Indeed, the full coverage of the French territory with the metric precision digital landscape model (DLM) BDTOPO® is going to be achieved in 2007. The new flowline should derive the 1:25.000 and 1:50.000 digital cartographic model (DCM) from this DLM. A new project was entrusted with designing and developing this flowline. The challenges identified are :

· The use of multiple sources of data, to enrich BDTOPO® with data needed for the topographic maps.

· The conflation of these heterogeneous data.

· The use of automatic process to derive the 1:25.000 and 1:50.000 DCMs from the DLM according to [TREVISAN 04].

· The capability to ensure a rapid and reliable mechanism for propagating updates stemming from the DLM into the DCM.

· A join management of the two scales (1:25.000 and 1:50.000) in all the flowline.

· A full coverage of the French territory in one database, with the open-source database management system (DBMS) PostgreSQL and the spatial cartridge PostGIS [POSTGIS 06].

· A technological compatibility with future “maps on demand” services (potentially web services).

· A use by about hundred operators in a user-friendly environment.

· A use in six production units dispatched in different places in France.

In order to tackle these problems, numerous research technologies have emerged and are mature enough to become industrialized: automatic conflation tools for multiple sources of data [MUSTIERE 06], automatic generalisation data process with agent-based methods [LECORDIX et al. 06], tools for propagating updates between different geographic databases [BRAUN 04]. Some of these technologies have already been embedded at IGN in a new process for the 1:100.000 topographic map series now industrialized [JAHARD et al. 03]. Taking benefits from these results, the new project is managing more ambitious targets with more production constraints.

This article will present the first results of the project, especially:

· The design of the software architecture that allows for the management of very large database (multi-scales, unbroken on the full territory) and for the decentralization of the production.

· The technologic options chosen to ensure the compatibility with future cartographic (web) services.

· Some results of automatic process (recovery of heterogeneous data, conflation, generalisation) initially stemming from research prototypes, but embedded in robust and user-friendly software environments.