Design And Implementation Of The Electronic Drawing Data Conversion System Based On GDF

Currently,NAVTEQ and Tele Atlas,the two biggest provider of base electronic navigable maps,are using GDF(Geographic Data Files)as the raw data for navigation map displaying.However,data in this format is associated loosely with a high redundancy.As a result,it has a very rigorous demands for hardware and a relatively low rate.To cut the cost and improve the performance,we need to provide a data format with lower redundancy and strong correlation.In this article,I will introduce you the digital map transformation system which was developed with C++.To achieve this,I will investigate the properties of GDF,discuss the basic design principles of GGD(Geography Graph Data)format,analysis the internal connection between GDF and GGD and researches the problems about compressing shape points,polygon self-intersecting and processing of polygons with holes,and many other key technologies.About the software development,test-driven is approached.I test the correctness and robustness of the codes with unit testing and use the thinking of design by contract to ensure the normal operation of the system.At last,I will suppose the problems which may appear and the jobs need to be done futher.The long period of professional testing shows that,the electronic map transformation system is able to reduce the requirements of navigation machine hardware and the time of loading of the map cluster greatly.Currently,the system has been used by a number of large projects depot for mass production.