Research Of 3D Lifelike Terrain Display Technology Based On OpenGL ES

By the development of the domestic general aviation industry,the demand of3D(three-dimensional)navigation applications and equipment is increasing with a large potential market.However,products of 3D navigation equipment for general aviation are rare but expensive.Therefore,the study of low-cost and high-quality 3D navigation equipment is very valuable at market.With the improving computing and storage capabilities and excellent display interface of smart mobile devices,this paper studied the 3D display technology of real terrain in order to develop a 3D navigation application at last.The main points of the study are as follows:Using the Andriod operating system as the platform,the OpenGL ES as the graphics processing interface for 3D modeling: generate a realistic terrain image of a three-dimensional terrain by perspective projection;achieve the transformation,rotation and scaling of the terrain by coordinate transformation;construct 3D terrain model through wireframe grids at line mode.The real-time optimally adaptive meshes(ROAM)algorithm was realized with a reduce of 92.7% on surface units,and an increase of 71.4% on FPS(Frames Per Second).The characteristics of visual attention are analyzed for improving the criterion of node segmentation in the algorithm,which further reduces the number of units drawn by each frame with a reduce of 27.3%,and thus improves the drawing efficiency In the premise of retaining terrain characteristics.In addition,the original visibility determining method of the algorithm was optimized and the vertexes of patches are considered instead of center to decide the visibility,which eliminates the sawtooth phenomenon at the view edge.For practicing the application of 3D terrain display technology,function module design and implementation of a terrain roaming application were achieved: use texture mapping technology to increase the realism of terrain;build a real background through the sky box technology;the control of the viewpoint position and viewing angle were achieved by using the touch response;and apply the Location Manager class to get and show the information of location.Finally,a real-time 3D terrain roaming application with good real sense and human-computer interaction function was completed.