| 摘要 |
PROBLEM TO BE SOLVED: To expand a range capable of applying an object included in new map data in map data updated every year. SOLUTION: An effective period indicating a period in which the actual geography is expressed by the object is given to each object composing the map data. In a newly issued map data, information indicating the existence of modification is added to the object in addition to the effective period. A map display device reflects a modification content included in the new data on the other already stored past map data when the modification exists. In displaying a map, the reflected newest data are used. In addition, map display using previous data is enabled in response to designation or the like of a user. Thus, when an error of the object is detected, a new object can be applied back to issuance while an old object remains. COPYRIGHT: (C)2007,JPO&INPIT
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