1. Field of the Invention
This invention relates to an information retrieval system and information retrieval device which retrieve position data and related data, for example using the Internet, and display them.
2. Description of Related Art
The Internet comprises a service referred to as the WWW (World Wide Web), which performs multimedia data retrieval via the network based on hypertext linking character information, image information and audio information. An enormous amount of information of many kinds can be accessed using the WWW ranging from technical data and economic information to shopping and restaurant information. There are also many types of WWW sites ranging from official bodies such as Governments and local public authorities to small companies, shops and even individuals. It is moreover envisaged that services using the WWW will undergo even further expansion in the future.
When these WWW services are used, information about shopping and events can easily be obtained. However even if such information is acquired, map information is required to know exactly where a shop is located, or where an event is being held. When the WWW provides shopping or event information, it would be desirable if the location of a shop or event were displayed on a map. The WWW uses hypertext, so if a map of the nearby area is prepared as image data, and the location of the shop or event is marked on the map, the map can be marked at a predetermined position on a predetermined page.
However, roads and topography are extremely complex, and it is therefore very difficult for persons preparing Www pages to construct maps near shops or events, and paste them on predetermined pages. Also, the maps drawn by WWW page authors are frequently inaccurate.
A WWW site providing map data could be envisaged wherein, when position data such as latitude or longitude is input, a map corresponding to the specific position is displayed. If there were such a WWW site, a user who acquired shopping or event information could then open a WWW search page providing this map data, and find the location of a shop or event on a map by inputting its position.
To retrieve the map data, exact position information such as latitude and longitude are required. However, information regarding a shop or event generally includes only the shop name or event venue, telephone number and address, etc., and absolute position information such as latitude and longitude is almost never given. Therefore, even if map positions of shops or events are searched using a WWW site providing such map data, they are of no use if the absolute position of the shop or event is unknown.
CD-ROM's are on the market which contain map data, and a map display application which displays a map around a place when the place is specified, so it would seem feasible to use the map data in such a CD-ROM. Using the CD-ROM application, it is possible to retrieve the map data position for a shop or event.
This CD-ROM could also be used when preparing map data at sites which provide shopping or event information on the WWW. In other words, sites offering shopping or event information on the WWW would extract positions of shops or events from the map data in the CD-ROM. A shopping or event information page would be prepared, and map data from the CD-ROM would be pasted on the page. In this way, persons preparing WWW pages could paste accurate maps on pages without drawing maps themselves.
However, map data is constantly changing. New buildings are erected, old buildings are demolished, and cities are always in a state of flux. There is also regional development and new roadworks. Hence, if map data in a CD-ROM was used, it would be difficult to cope with these changes in the data. Also the maps used with the WWW would include all kinds, from full coverage maps of the whole world to detailed maps showing shops belonging to private individuals in various world areas and of various scales. CD-ROM's have a data storage limit, and cannot satisfy such wide-ranging demands.
Further, if WWW pages are prepared using the map data in a CD-ROM, the map data would be used without restriction and it would be difficult to protect copyrights.