The Realization Of Electronic Chart & Radar Image Overlapping Display

The application and development of modern navigation information technology makes electronic chart and radar image overlapping display possible and inevitable, which supplies the security for marine navigation and collision avoidance. Radar image overlaps on the electronic chart, which reveals the position relation amang the ship, static targets and dynamic targets around the ship accurately on the basis of chart information navigational water area. This device not only enhances the information display capability of electronic chart system, but also improves the collision avoidance capability of radar.The powerful data processing and display function of computer has been utilized to realize radar video digital information to overlap on the electronic chart real-time, fastly and precisely, with electronic chart for ground floor and radar image for dynamic layer. The static targets of radar has accorded with the corresponding targets of electronic chart, while it has revealed positionally the dynamic targets of radar on the electronic chart real-time and accurately.According to the status quo and development trend about electronic chart and navigation radar used by ships, the paper has analysed the structure and function of electronic chart & radar image overlapping display system on the whole firstly and has put forward software design project based on modularization that three modules has been compartmentalized such as electronic chart display, radar image display and overlapping matching. And then, it has spread to research each module separately. Refered to IHO S-57 transfer standard, the module of electronic chart display has read, converted and saved the chart data structures that meet the IHO S-52 standard. It has fulfilled the display of chart subsystem by means of several technologies that have improved the speed of chart display. The module of radar image display has made use of high precision coordinate transformation and fast refreshing technologies to attain the real-time require. The phenomenon of blind region and fatal address have been restrained effectively. The module of overlapping matching has analysed and revised the error that has brought by hierarchical display of electronic chart, radar image and secondary targets, has brought forward real-time matching algorithm based on XOR and multiple technologies that has been used to quicken the speed of matching, and has realized two display way including real-time matching display and radar targets simulation. In conclusion, the paper has summarized main research achievements of the whole design, pointing out existent defects.The paper has contrived the good human-computer interaction interface, has actualized the basic function operation, and has adjusted the scale of chart and the capacity of radar suitably in the light of design principle of the maritime traffic management human-computer interface. This system has realized the high precision real-time matching positioning about electronic chart and radar image in possession of high practical value.