Integrating semantics into the interoperable 3D GIS CityServer3D

In this paper, the authors present a practical approach to design and implement an interoperable three-dimensional geographic information system. Besides the described system concept combining visualization and GIS-driven requirements the concept uses up-to-date software engineering techniques to realize a sustainable and extensible 3-tier software system. The first part describes the general architecture and the specific patterns used to overcome the software engineering hurdles and attaining the goal of geometric interoperability. These include the use of a common functional model to cleanly separate interfaces, data sources and processing and the use of facades and orchestration mechanisms for the establishment of communication between systems. The second part concentrates on managing the semantic lifecycle of GIS data in the described system. Since it is to be used in various domains and by heterogeneous user groups, an ontology driven approach was developed. Hereby, semantics are managed by using and extending several OGC-standards. FeatureTypes are used as an essential component for the ontology modeling. By combining FeatureTypes and ontologies and by a slight extension of the Simple Feature specification, this approach allows the assignment of features, which possess ontology-dependent attribute definitions, to different domain ontologies. Following the summary an outlook on further developments like an extension of OGC web services by ontology-driven queries is given.