US Patent 11567928 Apparatus and methods for updating a map database

An apparatus, a method, and a computer program product for obtaining map update data of a region are provided. The method comprises determining an update candidate node, wherein the update candidate node is associated with a node identifier and a first node digest; sending the node identifier and the first node digest to an update data service; and receiving, from the update data service, a response containing one of node digests of the child nodes of the update candidate node at the update data service; or updated content corresponding to the update candidate node. The method may further include updating the map database based on the received response.