Research And Imlementation Of Portable Terrain Awareness System Based On Digital Elevation Map(DEM)

Airborne terrain awareness and warning system is mainly used by large and medium aircraftin the transport aviation, and is difficult to be directly applied to general aviation. As a part of the project named "Research of the Portable Terrain Awareness and Warning System Based on Digital Elevation Map (DEM)", this paper aims to develop a portable terrain awareness prototype system according to the practical demand of the general aviation. As a computer aided tool, the system tries to improve the terrain awareness of pilots through the dynamic display of topographic mapin intuitive and concisemanner.The key technologies for low cost and portable terrain awareness system are studied, a prototype system is developed, and the simulation test is carried out. The system is based on the mobile computing, satellite positioning, micro sensor and digital elevation model. Based on the traditional contour extraction algorithm, this paper establishes a set of contour points after the interval tree index is established, and then the contour points are found out. The DEM data are pretreated by the interval tree, which improved the extraction rate of contour lines. According to the system requirements, the terrain map is filled with the scan filling algorithm to generate the terrain map quickly. In the system, the aircraft position and altitude data are acquired by different sensors, and then flight parameters are calculated. When aircraft parameters changes, the DEM database is used to extract the dataquickly and the terrain map is filled, colored and refreshed at regular time. The scanning and filling algorithm is used to refill the topographic mapwhen the latitude and longitude of the aircraft changes.The change of course is presented by rotating the topographic map when the aircraft heading changes.The bilinear interpolation is used to scale of the topographic map when the pilotneeds a different view of the terrain map.At last, the prototype system is verified by simulation. The testing result shows that the system can display the terrain map nearby theplane in the course of flight with the changes of flight parameters dynamically, and distinguishgrade of the terrainbydifferent colors.The dynamic following display of the terrain map near the route is realized preliminarily. It is an effective assistant tool to improve the terrain perception ability of flight crews.