A Study Of Developing Electronic Navigational Chart Display In Embedded Linux Environment

Chart is always essential for navigation, especially for seamanship and shipping management, electronic navigational chart presents more advantage than the traditional navigation chart which is made up with paper. It becomes possible and easy via the ENC to process route design, real-time display ship's position, monitoring course and track, navigation auto-alarm and so on.With the rapid development of electronics and information technology, lots of countries start to develop their own ECDIS to well serve navigation. Since the informationization in China is comparative late, the ECDIS development is still at primary stage. It is important to develop our own ECDIS. The main purpose of this paper is to develop ENC display system complying with S-57 and S-52 standard, which is the kernel part of ECDIS. To be explicit, the research content is to display the ENC in Linux embedded OS environment, as the base and initial framework of ECDIS on Ship.The paper analyses ENC display flow and divides it into 6 child modules to implement step by step, which are S-57 file parsing, S-52 presentation library parsing, S-57 and S-52 data fusion, coordinate conversion, GUI construction and vector chart display on server.Among the above, parsing S-57 and S-52 files is more complicated than others. However, GDAL supports some API functions which could be used to get objects information. Then S-57 file parsing could be easy done with assistance of GDAL open source library. S-52 file could be considered as the object display style database. With the S-57 information parsed in last step, it is possible to get objects'display style from S-52 file, and even to parse the display style since the style descripted in S-52 has its own syntax. The next step is to collect all information with some reasonable datastruct. After getting all information displaying charts by parsing, the following task is just to display layeredly the graph with OpenGL on X window graphics system and use GTK+ to construct the GUI (Graphic User Interface).The paper makes an analysis of all child modules of ENC display, and finally finishes the ENC standard display which complies with S-52 standard and verified with a good performance. Besides that, it also analyses the porting feasibility in Linux environment from desktop to embedded system, and give the explicit work about porting. All the work lays a solid foundation of developing the embedded ECDIS equipment. Among the above, the most difficulty and the main task is to process the information translation from the primary S-57 and S-52 file into the data accepted by OpenGL becomes the main task of displaying ENC.