Patent ID: 8799246

Claim:
An apparatus comprising: a map data storage device configured to store map data representing arrangement of map elements, the map data not being stored in units of blocks of a map; a map update device configured to reflect a first map update of a first map element to a first version of the map data to produce a second version of the map data when the first map update occurs, the map update device configured to reflect a second map update of a second map element to the second version of the map data to produce a third version of the map data when the second map update occurs after the first map update; a determination device configured to determine whether the first map update and the second map update depend on each other by determining whether there is a connection between the first map element and the second map element; and a data production device configured to produce map differential data in units of map elements rather than blocks from the first map update and the second map update when the determination device determines that the first map update and the second map update depend on each other and distributed to a navigation apparatus in response to a user request, wherein when there is the connection between the first map element and the second map element, the determination device determines that the first map update and the second map update depend on each other, the first map element and the second map element are different from each other; the first map element is a first road; the second map element is a second road; when the first road and the second road are directly connected to each other in the third version of the map data, the determination device determines that the first road and the second road depend on each other, and the first road and the second road are grouped together into the map differential data due to their dependencies on each other; when the first road and the second road are not directly connected to each other in the third version of the map, the determination device determines that the first road and the second road do not depend from each other and the first road and the second road are not grouped together; and the grouping together requires the apparatus to provide current latest version of map data with each of the second version and the third version of map data wherein a controller determines by comparing whether the content of current map update reflected to the current latest version of map data depends on the content of the previous map update reflected to the second version of map data and the third version of map data.