Map-based range query processing for geographic web search systems

In order to utilize geographic web information for digital city applications, we have been developing a geographic web search system, KyotoSEARCH. When users retrieve geographic information on the web, specifying geographic location is an essential function. However, most current web search systems do not utilize location information sufficiently well to identify the user's intentions; available methods employ just keywords (for location names) and limited map functions. Furthermore, most map interfaces are used to select a determined geographic-hierarchy level or point to a specific location (sometimes specifying a radius). In this paper, we introduce two-dimensional range query processing for geographic web search, where users are able to specify a geographic area freely on a map interface. In order to handle such range queries more rapidly and efficiently, we adopt geometric operations to retrieve proper web pages. Without optimization techniques, however, the recall and precision of the search results become very low. Major problems come from erroneous extension of the computed geographic area due to i) same names for different geographic objects/locations (geowords), ii) redundant geographic hierarchy information, and iii) existence of non-important geowords. By resolving these problems, we can improve range query processing for geographic data. To that end, we propose an effective geographic scope optimization method for that supports geometric operations in geographic web search; experiments conducted on an implemented system are described.