A DISTRIBUTED SYSTEM ARCHITECTURE TO PROVIDE ON-DEMAND MAPPING
Ordnance Survey, Ordnance Survey Reasearch Labs, Southampton, UK
Traditionally, map providers have been designing their range of map products to respond to the needs of different groups of potential customers. The products are usually based on data that they collect and maintain. The current map production systems involve a large amount of manual work, which limits the possibility of producing more user orientated products (responding to the need of a particular user). The cost would be prohibitive.
In the last few years, we have seen a few examples where production lines have integrated automatic processes to reduce the production costs. Much research has been done on automatic generalisation, and we can hope that in a few years time, we will be able to generate maps of reasonable quality from a geographical database using mostly automatic processes. For Ordnance Survey, Great Britain’s national mapping agency, it means new opportunities, but also new challenges to overcome.
We need to consider how we can give the control to the user about what he wants to have in his product, and how it is represented. The “what” would specify what data need to be used, and the “how” specify how they should be represented in the dataset or in the map, depending whether the purpose of the product is analytical (dataset to perform analysis) or contextual (a map for visual interpretation).
The first challenge is to allow the user to design a map without himself having any cartographic knowledge. We also want him to be able to combine data from multiple sources to produce his map. Designing a system that can understand unknown data is therefore another challenge.
The paper describes an architecture for a system capable of tailoring user-designed cartographic products. We propose a distributed architecture that will allow different parts of the system to be implemented in different environments, to take advantage of the most appropriate technologies. Ontologies will be used to store the knowledge required by the system. Different ontologies will be required to store the knowledge about the data, about cartographic generalisation and about cartographic design. The generalisation tools will be accessible as services, and the services will be described using the concepts (generalisation operations, geographic entities and context) defined in the different ontologies. The system will reason on these ontologies, to interpret the input data and to help select and control the generalisation tools used.