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| Fig.1. An architecture of Mobile Info Search |
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| Fig.2. Index of Mobile Info Search |
How to collect and index resources associated with places or areas is an important issue for the location dependent information service. We are developing software to utilize the Internet resources relevant to some locations and we have been testing the portal site "Mobile Info Search" (http://www.kokono.net/ and its English ver.) to provide Japanese local information for mobile users. Core technique of Mobile Info Search is "Automatic Location Metadata Generation" that extracts the address strings from the original resource, converts the address strings to the coordinates by looking up the location information repositories, generates a metatag which represents the relevant location to the resoure, and index them for searching or mapping. The technique, the system and the experimental results are reported.
On the Web, we can find many resources associated with a particular location. But, automated discovery and geographical indexing for these resources are not easy. Some of these resources include address or some other strings that describe the location they associated with but they do not explicitly. There also are resources that can be accessed through a certain query with a certain notation of location. We are developing the techniques that mediates these resources for each location that the user is or wants to find information.
Mobile Info Search is open to the public on the Internet since 1997 as our test service. From the address http://www.kokono.net/ , anyone can enjoy both searches. When user access to the Mobile Info Search, the index page of the location is automatically displayed (Fig.2). User's current location is displayed as the address, the longitude-latitude, and the nearest station on the top of the page. About 20 WWW services, provided by the courtesy of 8 companies are available. They include following; kokono Search, Yellow Pages and Restaurants guide under the Shops information, several maps, train tables, hotel guides and reservations, weather reports, and TV listings. This index page can be generated automatically for any Japanese location requested.
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Both location information from the user and for the information sources are in various form. It can be address strings, longitude-latitude, postal-codes, or landmarks. The mediator converts the user location into the location information suitable for the target using the location information repository. The repository we constructed on Mobile Info Search is the set of location information that can convert each format to others. This mediation software is prepared manually for each services. The access method, the request form, and the usage of local information of the target is defined in the software.
Location-Oriented Meta Search performs in following way;
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kokono Search provides the spatial search that searches the document close to a location. Just like other search engines, it employs a software called "robot" or "spider" that collects documents from the Internet and creates local database for collected documents. While other search engines provide a keyword-based search, kokono Search do a location-based spatial search. It displays documents in the order of the distance between the location of the document and the user's location.
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| Fig.3. Automatic Location Metadata Generation |
We analyzed about half million (479,669) documents collected and organized by Automatic Location Metadata Generation and found about 40 % (210,369) of documents contained address strings (Table 1.). As some documents contains more than one addresses, we collected 1,122,380 total addresses. The collection rate for addresses is shown in Table. 2. We collected almost every cities, 30.3% of towns, and 6.8% of Chome level addresses of Japan. Collecting some deeper addresses from the Web pages is not a easy matter. Because some Chome or deeper level addresses are used only for describing the location for personal houses, they may not appear on the Internet.
| Table 1. Numbers of collected documents | ||||||||||||||||||||||||
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| Table 2. Collection rate of documents for Japanese addresses | ||||||||||||||||||||
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