Map Data Updating Method And System

The invention is a map data updating method for updating map data on a client device () by means of a server () storing a latest version of the map data, wherein the map data comprises map tiles having layers. The server () stores association information defining groups of associated layers, wherein each layer in a group is updated on the client device () if an update request for at least one layer in the group is received by the server () from the client device (). The invention also relates to a map data updating system, a computer program product and a computer-readable medium for implementing the method.