Research On The Technology Of Electronic Chart's Seamless Conjoin Display

Depending on the advanced development from single electric chart file to multiple electric chart files of some electric chart file display and information system (ECDIS), the system design method of seamless conjoining and endless Navigation Display, which is based on multiple electric chart files's conjoin, is proposed in this thesis.Firstly, this thesis analyzes the data format and the symbol library of electric chart file and their relationship. Based on these, single chart file searching and displaying method is proposed. Secondly, the conjoining and display principle of electric chart files and the framework and components of system are proposed. Then the thesis lays strong emphases on the research of some key techniques in the seamless conjoin, which are below.(1) Propose the fast navigation and display mechanism of electric chart based on the technique of memory bitmap.(2) Describe the mathematics fundament in the conjoining and display of the electric chart file detailedly. And several basic coordinate systems and the coordinate transforming among them are discussed. Then propose a coordinate unifying method of electric chart file in different styles of projection and coordinate systems.(3) Propose a simple but effective index mechanism of electric chart file and give the corresponding fast search algorithm based on the data characteristic of electric chart file and the practical need of seamless conjoin.(4) According to the practical need of seamless join, propose a clipping method of multi-rectangle region, then the corresponding clipping and conjoining process of multi-file and the method of limitless zooming is presented. The seamless conjoining and display method, which is proposed in this thesis, have already been used successfully in some electric chart file system.