Visual Query Language on Spatial Information (SIVQL) is one kind of visual query language based on the extension of Query by Example (QBE). It is a visual operation based on graphics or media object, such as point, li...Visual Query Language on Spatial Information (SIVQL) is one kind of visual query language based on the extension of Query by Example (QBE). It is a visual operation based on graphics or media object, such as point, line and area elements. In this paper, the relation calculation and query function of SIVQL have been studied and discussed by using set theory and relation algebra. The theory foundation of SIVQL has been investigated by the mathematical method. Finally, its application examples are also given with the specific information system.展开更多
Visual queries assist non-expert users to extract information from spatial databases in an intuitive and natural approach,making Geographic information systems comprehensive and efficient for a wide range of applicati...Visual queries assist non-expert users to extract information from spatial databases in an intuitive and natural approach,making Geographic information systems comprehensive and efficient for a wide range of applications.A common visual means of querying takes the form of drawings or graphs,under which many spatial ambiguity and translation errors rise.In this study,common query attributes extracted from user graphs such as spatial topology,size,cardinality,and proximity are regarded under a conceptual moderation scheme.Thus,the system/user may concentrate on various conceptual combinations of information.Furthermore,time is incorporated to support spatiotemporal queries for changing scenes and moving objects.Arbitrary,relative,and absolute scaling is possible according to the data-set and application at hand.The theoretic approach is implemented under a prototype user interface system,called ShapeController.Under this prototype,a user may extract scene-based relations in an automatically inferred fashion,or include single object-oriented relations when all possible relations seem redundant.Finally,a natural language description of the query is extracted upon which the user may select the desired query relations.Experimentation on a spatial database demonstrates the concepts of predefined draw objects,scaling relaxation,conceptual abstraction,and scene,object-and textual-oriented transitions that promote query expressiveness and restrain ambiguities.展开更多
文摘Visual Query Language on Spatial Information (SIVQL) is one kind of visual query language based on the extension of Query by Example (QBE). It is a visual operation based on graphics or media object, such as point, line and area elements. In this paper, the relation calculation and query function of SIVQL have been studied and discussed by using set theory and relation algebra. The theory foundation of SIVQL has been investigated by the mathematical method. Finally, its application examples are also given with the specific information system.
基金supported by the basic research grant of the Special Account for Research of the Technical University of Crete for the project“Spatiotemporal queries by sketch in moving object geographic databases”(No.80080).
文摘Visual queries assist non-expert users to extract information from spatial databases in an intuitive and natural approach,making Geographic information systems comprehensive and efficient for a wide range of applications.A common visual means of querying takes the form of drawings or graphs,under which many spatial ambiguity and translation errors rise.In this study,common query attributes extracted from user graphs such as spatial topology,size,cardinality,and proximity are regarded under a conceptual moderation scheme.Thus,the system/user may concentrate on various conceptual combinations of information.Furthermore,time is incorporated to support spatiotemporal queries for changing scenes and moving objects.Arbitrary,relative,and absolute scaling is possible according to the data-set and application at hand.The theoretic approach is implemented under a prototype user interface system,called ShapeController.Under this prototype,a user may extract scene-based relations in an automatically inferred fashion,or include single object-oriented relations when all possible relations seem redundant.Finally,a natural language description of the query is extracted upon which the user may select the desired query relations.Experimentation on a spatial database demonstrates the concepts of predefined draw objects,scaling relaxation,conceptual abstraction,and scene,object-and textual-oriented transitions that promote query expressiveness and restrain ambiguities.
