The Research On The Key Technologies Of The ENC Based On VC

With the rapid development of ocean shipping industry, electronic navigation charts have become an important tool to ensure the safety of navigation. The paper chart has been replaced by the ENC, because the ENC took the advantages that its convenient storage, larger capacity, and it was easy to modify. No only radar, sonar, compass, GPS and other information could be dealt conveniently by the system, but it also could facilitate the realization of the map for the seafarers. A lot of key technologies was involved in the ECDIS, such as the analysis of ENC document, the design of SENC, the data retrieval chart, the theory and algorithm of Mercator projection and Gauss projection, the cutting and display of electronic navigation chart.By using VC++integrated programming environment to implement some core technology design for this system, much researches on the key technology of ENC displaying had been done by this paper, especially ECDIS displaying.Firstly, the appearance and development of the ENC were introduced. In this part, some elements related with EDIS including concept, composing. function, etc. Besides, the development condition of this system internal and external the country had been analyzed, too.The theoretical model, data structure and the packaging standards of S-57 format charts was researched by the study. And the characteristics of S-57 format chart data had also been clarified. Besides the coding style of ENC had been illustrated with examples. This research deeply analyzed the necessity of SENC design, which also included the necessity of ENC analysis. And the basic principle and total requirement was given by this paper. Based on existing documents, a SENC format design was provided. A detailed explanation with practical coding examples was given to this research at last.The theory and algorithm of the Mercator and the Gaussian projection had been researched in this study, what's more a description for the method of the conversion of geographic coordinates to projection coordinates had also been given, it discussed the selection of reference points especially. Finally, the advantages and disadvantages and the use scope of two projectors to be given more notes.Finally, the chart display information in accordance with the requirements of classification has been dealt in this subject, and it showed the hierarchical structure of information, given the calculation of the screen display area. Some sophisticated algorithms which was designed to cut the charts to be displayed had been taken to deal with the chart elements.. At last the ENC summary document will be appeared on the screen.The research of this theme has been applied to the Jilin Communications Ministry's project which is undertaken by GNSS Institute in Dalian Maritime University. The project's name is "watercraft dynamic monitoring information system". The research result has had application in the project.