The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008
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The hybrid ontology approach (Visser, U. & H.
Stuckenschmidt, 2002) is used, as shown in Figure 3, in our
conceptual framework to make user ontology and domain
ontologies used in description of geographic information. Top
Level Ontology is a general ontology shared by user and
description provider. It’s a medium component to communicate
between user ontology and domain ontologies in the proposed
model above.
4.2 Ontology-based method
Based on the above hybrid ontology approach, a method is
developed for discovery and retrieval for geographic
information, as showed in Figure 4.
There are three main steps in the method. First step, user’s
search terms are mapped into concepts in domain ontology
based on the hybrid ontology approach. Second step, the
concepts are expanded based on the hierarchy of concepts in
domain ontology. If the concepts have subclasses, then the
subclasses are added to expand the query. Otherwise, the
superclass is checked. If there is superclass, then the superclass
is added to expand the query. Third step, based on the query
expansion, suitable descriptions of geographic information are
searched and return to users. If the results are suitable, search is
finished. Otherwise, repetition from the second step is needed.
map user’ s
query to Domain
Ontology
expansion to
user’ s query
Search
Figure 4. Ontology-based method for discovery and retrieval
5. CONCLUSION
In this paper, we proposed an ontology-based semantic
description model for geographic information. The model is
able to solve problems of semantic heterogeneity in description
by introducing ontologies which enrich semantics of
geographic information. Besides, an ontology-based method
for discovery and retrieval is discussed to overcome shortage
of approaches based on keywords. The method make user’s
query more exactly in expression meanings of request. Thus,
suitable geographic information are discovered and retrieved.
Of course, there are still some works need to do in future.
Sufficient algorithms for building mappings between
ontologies still need to present. Besides, implementation for