SPATIAL STRUCTURES AS GENERALISATION SUPPORT SERVICES

While standards for automated access and presentation of cartographic data over the internet are defined, services for automated generalisation and the transfer and storage of the data involved are not yet standardised. Web service technologies can be used to establish an interoperable framework between different generalisation systems. The service architectures can be distinguished into middleware services, which are delivering original and/or pre-generalised data from a database through a WMS or WFS, and research platforms which provide only access to the generalisation operators and can be used with own data. Three categories of generalisation web services are identified. Support services are enriching the raw input data with additional information or expressing structural and spatial relationships. Operator services deliver the functionalities of individual generalisation operators and take enriched data as input. And finally, process services use the two other service types in order to control the generalisation process. The modelling of structural and spatial relationships is critical for the understanding of the role of cartographic features and thus for the automated generalisation. On one hand the relationships can be hierarchical structures between map features or feature classes. On the other hand there can be relations between the features themselves which can be expressed by matrices or graphs. This paper aims to discuss and define which types of support services can be established for enriching the raw input data and how the complex output of such services can be represented and used in a web services environment.