LINKING DIFFERENT GEOSPATIAL DATABASES BY EXPLICIT RELATIONS
Steffen Volz *, Volker Walter
University of Stuttgart, Institute for Photogrammetry, Geschwister-Scholl-Str. 24D, 70174 Stuttgart, Germany -
(steffen.volz, volker.walter)@ifp.uni-stuttgart.de
Commission IV WG IV/2
KEY WORDS: GIS, Integration, Interoperability, Open Systems, Federated, Spatial Infrastructures
ABSTRACT:
The growing awareness of the importance of spatial information has led to a continuously increasing demand for geospatial data.
Thus, a lot of different companies and institutions have evolved that are aiming at satisfying this demand by capturing the real world
according to the needs of different applications. This process involves that one and the same real world object is stored in several
representations in different geospatial databases. The integration of these representations is a major research challenge in the field of
GIS. In our approach we use a semi-automatic matching tool for defining relations between representations on the instance level.
These relations are used in order to automatically derive an integrated data schema. The relations on the instance level as well as the
integrated data schema can be used for automatically merging data sets, for automatically transferring updates from one data set into
another or for a common analysis of spatial data from different sources.
1. INTRODUCTION
Many organisations have made major investments in capturing
spatial data. However, an exchange of these datasets or a
combined use is done only very rarely. This situation is going to
be changed by using new internet technologies. One of the
driving forces in this field has been the development of Web
Services for Geographical Information Systems. Web Services
are interoperable applications that are accessible with
standardized interfaces in the internet. With that kind of
technology it is possible to write platform independent
programs which can be shared between different users.
Therefore, Web Services could be seen as the basic technology
for interoperable Geographical Information Systems. Web
Services are also the basis for the realisation of Spatial Data
Infrastructures. The aims of these infrastructures consist of
improving the quality of data, reducing costs, making data more
accessible and providing consistent datasets.
However, very often, one main important aspect is ignored here.
It is not sufficient to provide only platform independent
programs to realize Spatial Data Infrastructures; it is also
necessary to provide integration techniques for spatial data.
Because the data are captured by different organisations, one
object of the landscape is stored in several databases in different
data models, at different acquisition times, with different quality
characteristics or in different scales.
The integration of spatial data can be done at two levels: (1) an
integration of the spatial instances or (2) an integration of the
data schemas. Research in the spatial domain was mainly
focusing either on matching techniques on the instance level or
on ontology based approaches on the schema level. Up to now,
no approaches could be found which are combining the two
paradigms. In this paper we examine how the integration of
different data schemas can be derived automatically from
integrated data instances (see figure 1).
* Corresponding author
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Basic idea: deriving schema relations by
analyzing instance relations.
Figure 1.
The integration of data instances is typically done with
matching techniques. There already exists a lot of research on
how this matching can be done in an automatic way, but at the
moment there is no common approach, because this problem is
very application dependent. Therefore we use a semi-automatic
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