Alia I. Abdelmoty

The SPIRIT Spatial Search Engine: Architecture, Ontologies and Spatial Indexing

The SPIRIT search engine provides a test bed for the development of web search technology that is specialised for access to geographical information. Major components include the user interface, a geographical ontology, maintenance and retrieval functions for a test collection of web documents, textual and spatial indexes, relevance ranking and metadata extraction. Here we summarise the functionality and interaction between these components before focusing on the design of the geo-ontology and the development of spatio-textual indexing methods. The geo-ontology supports functionality for disambiguation, query expansion, relevance ranking and metadata extraction. Geographical place names are accompanied by multiple geometric footprints and qualitative spatial relationships. Spatial indexing of documents has been integrated with text indexing through the use of spatio-textual keys in which terms are concatenated with spatial cells to which they relate. Preliminary experiments demonstrate considerable performance benefits when compared with pure text indexing and with text indexing followed by a spatial filtering stage.

Ontology-Based spatial query expansion in information retrieval

Ontologies play a key role in Semantic Web research. A common use of ontologies in Semantic Web is to enrich the current Web resources with some well-defined meaning to enhance the search capabilities of existing web searching systems. This paper reports on how ontologies developed in the EU Semantic Web project SPIRIT are used to support retrieval of documents that are considered to be spatially relevant to users’ queries. The query expansion techniques presented in this paper are based on both a domain and a geographical ontology. The proposed techniques are distinguished from conventional ones in that a query is expanded by derivation of its geographical query footprint. The techniques are specially designed to resolve a query (such as castles near Edinburgh) that involves spatial terms (e.g. Edinburgh) and fuzzy spatial relationships (e.g. near) that qualify the spatial terms. Various factors are taken into account to support intelligent expansion of a spatial query, including, spatial terms as encoded in the geographical ontology, non-spatial terms as encoded in the domain ontology, as well as the semantics of the spatial relationships and their context of use. Some experiments have been carried out to evaluate the performance of the proposed techniques using sample realistic ontologies.

Maintaining Ontologies for Geographical Information Retrieval on the Web

A geo-ontology has a key role to play in the development of a spatially-aware search engine, with regard to providing support for query disambiguation, query term expansion, relevance ranking and web resource annotation. This paper reviews these functions, discusses the user requirements which influence the design of the ontology, with regard to different types of query and fundamental spatial concepts, before presenting a base model for a geographical ontology which will provide a foundation for subsequent implementation as well as experimentation with alternative ontology models. The report also reviews various ontology languages available for expressing ontologies and give examples for encoding the geo-ontology in them.

A critical evaluation of ontology languages for geographic information retrieval on the Internet

A geo-ontology has a key role to play in the development of a spatially aware search engine, with regard to providing support for query disambiguation, query term expansion, relevance ranking and web resource annotation. This paper reviews those functions and identifies the challenges arising in the construction and maintenance of such an ontology. Two current contenders for the representation of the geo-ontology are GML, a specific markup language for geographic domains and OWL, a generic ontology representation language. Both languages are used to model the geo-ontology designed for supporting web retrieval of geographic concepts. The powers and limitations of the languages are identified. In particular, the paper highlights the lack of representation and reasoning abilities for different types of rules needed for supporting the geo-ontology.

Building place ontologies for the semantic web:: issues and approaches

Place geo-ontologies have a key role to play in the development of thegeospatial-semantic web, with regard to facilitating the search for geographical information and resources. They normally hold large amounts of geographicinformation and undergo a continuous process of revision and update. This papers reviews the limitations of the OWL ontology language for the representation of Place and proposes two novel approaches to frameworks that combine rules and OWL for building and managing Place ontologies.

Viewpoints on emergent semantics

We introduce a novel view on how to deal with the problems of semantic interoperability in distributed systems. This view is based on the concept of emergent semantics, which sees both the representation of semantics and the discovery of the proper interpretation of symbols as the result of a self-organizing process performed by distributed agents exchanging symbols and having utilities dependent on the proper interpretation of the symbols. This is a complex systems perspective on the problem of dealing with semantics. We highlight some of the distinctive features of our vision and point out preliminary examples of its application.

A Filter Flow Visual Querying Language and Interface for Spatial Databases

In this paper a visual approach to querying in spatial databases is presented. A filter flow methodology is used to consistently express different types of queries in these systems. Filters are used to represent operations on the database and pictorial icons are used throughout the language for filters, operators and spatial relations. Different granularities of the relations are presented in a hierarchical fashion for spatial constraints. The language framework and functions are described and examples are used to demonstrate its capabilities in representing different levels of queries, including spatial joins and composite spatial joins. Here, the primary focus is on the query language itself but an overview of the implemented interface of the language is also provided.

Semantics, ontologies and eScience for the geosciences

Semantics, ontologies and eScience are key areas of research that aim to deal with the growing volume, number of sources and heterogeneity of geoscience data, information and knowledge. Following a workshop held at the eScience Institute in Edinburgh on the 7-9th of March 2008, this paper discusses some of the significant research topics and challenges for enhancing geospatial computing using semantic and grid technologies.

A framework for combining rules and geo-ontologies

Geo-ontologies have a key role to play in the development of the geospatial-semantic web, with regard to facilitating the search for geographical information and resources. They normally hold large amounts of geographic information and undergo a continuous process of revision and update. Hence, means of ensuring their integrity are crucial and needed to allow them to serve their purpose. This paper proposes the use of qualitative spatial reasoning as a tool to support the development of a geo-ontology management system. A new framework for the representation of and reasoning over geo-ontologies is presented using the web ontology language (OWL) and its associated reasoning tools. Spatial reasoning and integrity rules are represented using a spatial rule engine extension to the reasoning tools associated with OWL. The components of the framework are described and the implementation of the spatial reasoning engine is presented. This work is a step towards the realisation of a complete geo-ontology management system for the semantic web.

Order in space: a general formalism for spatial reasoning

We propose a general approach for reasoning in space. The approach is composed of a set of two general constraints to govern the spatial relationships between objects in space, and two rules to propagate relationships between those objects. The approach is based on a uniform representation of the topology of the space as a connected set of components using a structure called adjacency matrix which can capture the topology of objects of different complexity in any space dimension. The relationships between objects are represented by the intersection of the space components. The approach is also shown to be applicable to reasoning in the temporal domain and is used to explain the conceptual neighbourhood phenomenon related to the reasoning process. A major advantage of the method is that reasoning between objects of any complexity can be achieved in a defined limited number of steps. Hence, the incorporation of spatial reasoning mechanisms in spatial information systems becomes possible.