Several Technical Problems on Applications of Digital Map to Vehicle Navigation Systems

In this paper,the application requirements of vehicle navigation systems(VNS) for digital maps are analyzed first.Then the use of digital maps in VNS and some of its technologies are described in detail.The realization of many functions of VNS depends on digital maps and also puts forward some special requirements for the digital maps.It is necessary to set up the digital road map database of vehicle navigation oriented digital road map database.Some attributes of this kind of digital map database are discussed in this paper.In various kinds of VNS,the basic application of digital map is displayed.It can offer information to the user directly on the screen.In order to display the digital map onto the screen and change the displayed map quickly with the movement of the vehicle,the organization of the database is very important.A scheme on the organization of the database is presented in this paper.Some technologies of digital map display are also described.Because of the poor positioning precision of GPS and other positioning methods,the displayed position of the vehicle is often inaccurately out of the road.So the technology of map matching(MM) is widely used in VNS to improve the accuracy of positioning and the display result.A practical improvement of MM algorithms is presented in this paper.Lastly,a suggested multi-level organization scheme of digital road map database is proposed and discussed.