Research And Design Of Unified Symbols For E-vector Map Systems Of Sea Earth And Air

Map symbol system is an important part in the geographic information system. Relyingon an effective map symbol system, the user can get geographic information through theelectronic map display. Currently there are a wide range of standards for electronic mapsymbols, and as the departments get more and more closely linked, the need for integration ofdifferent sources of data processing and displaying is obvious as to meet specific needs.Therefore, designing a unified standard map symbol system applicable for data integrationhas become necessary.Based on analysis of the most commonly used land-maps and charts, together with thecharacteristics of the schema based on the knowledge of map semiotics, these symbols areintegrated, and a method to draw the correspondent symbol storage and symbol systemsframework is developed, which achieves a unified map symbol system design and applicationfor sea, earth and air.Firstly, based on the full study of land-maps, charts and standard schematic charts, thecharacteristics of a variety of electronic schematic symbols are analysed; according to theknowledge of map semiotics, map symbol system semantic unity and the principle of aunified graphical method and specific implementation steps are developed, which effectivelyunifies the above three kinds of electronic map symbols.Secondly, according to the knowledge of symbols, they can be divided into point, lineand shape symbols, and in accordance with the characteristics of each type of symbol, thedrawing method, storage structures and symbolic way are designed. Drawing method andsymbolic way of symbols for line and shape are improved effectively, in order to improve thedrawing accuracy and speed. Complex symbols are also under discussion, which broadens thescope of the study to draw symbols. Based on the above research, the procedure of designingand drawing of unified symbols are also discussed.Thirdly, according to the characteristics of sea, earth and air unified map symbols, modelare built and analysed to determine the main functions of the system. This paper alsodiscusses the basic framework of the system, class structure, index and symbol coding, whichconform to the unified management and usage.Finally, in the Windows-based platform for VC++6.0environment, a unified symbolsystem of all application modules is achieved, and the application is demonstrated in thecorrespondent system.