Design And Realization Of The Engine For Navigation Electronic Map

With the development of urbanization, cities become larger and larger, and roads become more and more complex. As an important part of the Intelligent Transportation System, the navigation electronic map can alleviate the inconvenience of the driving. Referring to the recent development of home and abroad, this paper puts forward the design targets for navigation electronic maps. The paper designs an engine for navigation electronic maps and proposes a scheme for navigation electronic map on embedded systems.Firstly the preprocessing of the electronic map data is introduced. The preprocessing criterion and two methods to preprocess electronic map data are presented. Secondly, based on the model of orienting objects, the data format for navigation electronic maps is designed which divides the map file to three parts: map header part, map index part, and map data part. This design makes it very fast to locate and load map data. Thirdly the design of the map data converting is discussed. The clipping algorithm for map elements against rectangle windows which divides the map data into blocks is adopted to reduce the loading data for map display. The rarefying algorithm for map spatial data is used to reduce the redundancy of map data. In order to reduce the calculations while displaying map, the placement of notation names on the map is moved to the data converting stage from the map display stage. This paper presents a weighted map matching method which considers almost all the factors that impact the map matching (e.g., the driving direction, the historical information, the distance information, traffic rules, road connectivity, etc). The two display modes of map also are discussed: the browsing mode and the navigation mode. Finally, the engine for navigation electronic map on an embedded platform has been implemented and tested. The test results indicate that this engine runs fast with low memory.