Automatic text processing: the transformation, analysis, and retrieval of information by computer
Automatic text processing: the transformation, analysis, and retrieval of information by computer
The design and analysis of spatial data structures
The design and analysis of spatial data structures
The TSIMMIS Approach to Mediation: Data Models and Languages
Journal of Intelligent Information Systems - Special issue: next generation information technologies and systems
Progressive approximate aggregate queries with a multi-resolution tree structure
SIGMOD '01 Proceedings of the 2001 ACM SIGMOD international conference on Management of data
R-trees: a dynamic index structure for spatial searching
SIGMOD '84 Proceedings of the 1984 ACM SIGMOD international conference on Management of data
DBXplorer: A System for Keyword-Based Search over Relational Databases
ICDE '02 Proceedings of the 18th International Conference on Data Engineering
VirGIS: Mediation for Geographical Information Systems
ICDE '04 Proceedings of the 20th International Conference on Data Engineering
Automatically and accurately conflating orthoimagery and street maps
Proceedings of the 12th annual ACM international workshop on Geographic information systems
Query processing in a geographic mediation system
Proceedings of the 12th annual ACM international workshop on Geographic information systems
Efficient IR-style keyword search over relational databases
VLDB '03 Proceedings of the 29th international conference on Very large data bases - Volume 29
Objectrank: authority-based keyword search in databases
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
An efficient information retrieval from plural independent databases partially unreliable
IMSA'07 IASTED European Conference on Proceedings of the IASTED European Conference: internet and multimedia systems and applications
An efficient information retrieveal from plural independent databases partially unreliable
EurolMSA '07 Proceedings of the Third IASTED European Conference on Internet and Multimedia Systems and Applications
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GIS data distributed in local, state, federal, and private data clearinghouses are being made accessible through the efforts of organizations such as Federal Geographic Data Committee (FGDC) and GeoData.gov. Many database applications, such as disaster management, transportation, and national infrastructure protection, need to access GIS information from such various data sources. In this paper we study how to answer keyword-based spatial queries approximately using information from heterogeneous GIS sources. An example query specifies the region of Orange County and keywords "junior schools," which asks for geospatial objects relevant to junior schools in Orange County. The answers to such a query provided by different sources differ widely in their content and quality. It is computationally expensive to access all the datasets to retrieve all the relevant objects. We develop approximate algorithms for answering such queries based on the local analysis of the query region using space-partitioning techniques. Our methods rank datasets in a partition based on parameters such as their spatial coverage and content matching the query keywords. The quality of the answers keeps improving progressively as we do deeper local analysis. We develop an efficient traversal strategy to maximize the quality refinement within a given time limit. We conducted experiments to evaluate the proposed techniques.