Electronic Chart Display And Navigation System Based On S-57 International Standard

This paper is a part of"Electronic Chart Display and Navigation System Based on S-57 International Standard". The following three parts are contained in this paper:The data struct and format criterion of S-57 international standard are particularly analysed. And the data's store and index struct, which made it more efficiently to read the decoded data, are particularly designed for the display of electronic chart. We improved arithmetics of Mercator mapping transform and inverse transform. Considering the arithmetic of Mercator mapping transform and its inverse transform,we give improving methods by using relativity of different standard parallel and fixed node iteration method respectively. We also programme to implement the improved arithmetic, and present the sample data.This paper also puts forward a new method based on polygons for route design which runs on the electronic chart display platform, and give the solution of computing the navigational distance. The route design contains two parts, one is to gain the network graph by polygon modeling to the electronic chart; the other one is to implement route design by an improved Dijkstra algorithm, and to analyse the efficiency of this improved algorithm. The voyage's computing also contains two parts, one is to transform screen to geographic coordinates, the other one is to resolve the equation of navigational route of invariable azimuth.