MetaData Retrieval (MDR) is a module for metadata retrieval of geo-referenced spatial locations. Metadata are annotations that assume the format of tags in the form of key=value. They come from the ontologies provided by Volunteered Graphical Information in WEB 2.0 applications, collaborative and open projects like OpenStreetMap (OSM) and GeoNames (GN). 'key' represents a concept, broad concept, while 'value' represents a specialization of the broad concept. Annotations are downloaded as XML files and validated by MDR. MDR adopts a Service Oriented Architecture with a web server based on Geoserver, a database system based on PostGres and PostGIS, while the graphical User Interface is in javascript and the application logic in java. The Graphical User Interface (GUI) of MDR is a sort of Query By Example. It presents to the user a multi-dimensional data model representing the spatial locations she/he might be interested to enrich with annotations coming from the web (OSM and GN). Thanks to the GUI, the user is allowed to specify in a user-friendly way, in an Abstract Specification Language (ASL) the specification of the interested spatial objects. ASL request is translated by the system into a set of SQL queries for PostGIS. There are two types of queries. The first type are queries searching for spatial objects satisfying the constraints in the various dimensions. The second type are queries searching for metadata already stored in the systems referring to the spatial objects specified by the first type of queries. The annotated geo-referenced maps are presented to the user in an interactive map showing the annotated spatial objects and the annotations in their hierarchical, ontological structure. After the user request an annotation is added permanently to the database system and will be later presented again to the user's requests.
MetaData Retrieval
MEO, Rosa;ROGLIA, ELENA;
2010-01-01
Abstract
MetaData Retrieval (MDR) is a module for metadata retrieval of geo-referenced spatial locations. Metadata are annotations that assume the format of tags in the form of key=value. They come from the ontologies provided by Volunteered Graphical Information in WEB 2.0 applications, collaborative and open projects like OpenStreetMap (OSM) and GeoNames (GN). 'key' represents a concept, broad concept, while 'value' represents a specialization of the broad concept. Annotations are downloaded as XML files and validated by MDR. MDR adopts a Service Oriented Architecture with a web server based on Geoserver, a database system based on PostGres and PostGIS, while the graphical User Interface is in javascript and the application logic in java. The Graphical User Interface (GUI) of MDR is a sort of Query By Example. It presents to the user a multi-dimensional data model representing the spatial locations she/he might be interested to enrich with annotations coming from the web (OSM and GN). Thanks to the GUI, the user is allowed to specify in a user-friendly way, in an Abstract Specification Language (ASL) the specification of the interested spatial objects. ASL request is translated by the system into a set of SQL queries for PostGIS. There are two types of queries. The first type are queries searching for spatial objects satisfying the constraints in the various dimensions. The second type are queries searching for metadata already stored in the systems referring to the spatial objects specified by the first type of queries. The annotated geo-referenced maps are presented to the user in an interactive map showing the annotated spatial objects and the annotations in their hierarchical, ontological structure. After the user request an annotation is added permanently to the database system and will be later presented again to the user's requests.
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