karla,Clodoveu§ Abstract. With the phenomenal growth of the WWW, rich data sources on many different subjects have become available online. Some of these sources store daily facts that often involve textual geographic descriptions. These descriptions can be perceived as indirectly georeferenced data- e.g., addresses, telephone numbers, zip codes and place names. Under this perspective, the Web becomes a large geospatial database, often providing up-to-date local or regional information. In this work we focus on using the Web as an important source of urban geographic information and propose to enhance urban Geographic Information Systems (GIS) using indirectly georeferenced data extracted from the Web. We describe an environment that allows the extraction of geospatial data from Web pages, converts them to XML format, and uploads the converted data into spatial databases for later use in urban GIS. The effectiveness of our approach is demonstrated by a real urban GIS application that uses street addresses as the basis for integrating data from different Web sources, combining these data with high-resolution imagery. 1

The expansion of the Internet and the number of its users has raised many new problems in information retrieval. The most common way to find information in the web is using web search engines. However, gathering information from the web is a difficult task for a novice user even if he uses the search engines. The user must have experience and skill to find the relevant pages from the large number of documents returned, which often cover a wide variety of topics.

We propose two-phase query modification using ontologies for geographic information navigators.