This paper presents a method for automatically generating large-scale road-network vector maps, based on GPS-probe-vehicle tracks. This method does not need to employ the basic maps of road-network maps, but only to use the tracks that are formed when GPS probe vehicles are moving in road networks, to reflect the real topology of road networks onto digital maps automatically. The proposed method consists of three steps: First, transform the earth longitude and latitude coordinates of the GPS-track data to the urban map coordinates, after that, generate the skeleton map of the road network by using the transformed GPS-track data, finally, perform the vectorization processing to the generated skeleton map. The experiments of automatically generating the real road network with the real-world GPS-track data indicate that the proposed method is able to automatically generate road-network maps successfully, and the generated vector digital map bears high accuracy and can satisfy the application requirement of automatically and timely updating the digital map in vehicle navigation systems, traffic guidance systems, etc. Source.