1. A method implemented at least partially by a processor, the method comprising: collecting a sequence of global positioning system (GPS) points for route-oriented vehicle logs; identifying geographical locations from the route-oriented vehicle logs, the geographical locations representing locations where route-oriented vehicles travelled as recorded in the logs; extracting route-oriented vehicle trajectories from the route-oriented vehicle logs, the route-oriented vehicle trajectories representing individual trips; and constructing a landmark graph based at least in part on the route-oriented vehicle trajectories by: associating each route-oriented vehicle trajectory to a corresponding road segment; and specifying a road segment frequently visited by the route-oriented vehicles as a landmark, a frequency being based on a number of route-oriented vehicle logs for the landmark.