A system includes a first module receives N points (N≧3) from a remote device, the N points indicating (i) a current location, (ii) a desired location, and (iii) one or more points between the current location and the desired location. A second module determines whether first information in a first datastore of the system is missing a link between each neighboring pair of points within the N points. A third module receives M points (M≧1) from the remote device for each missing one of the N−1 links, the M points indicating points between two of the N points associated with a missing link. A fourth module generates a route from the current location to the desired location based on the N points and the first information in a first datastore, and any M points received for missing ones of the N−1 links.