| As the development of the computer graphic, three-dimensional reality terrain becomes one of the most active fields in the computer graphic science. Three-dimensional reality terrain is wildly used in many aspects of society, such as outdoor network games, movie production, flight simulators and simulation of battlefield.During the resent years, generating three-dimensional terrain is one of the hotspot in researching the three-dimensional graphics. There are two steps for generating 3D reality terrain: terrain modeling and terrain rendering. It is important to model terrain for generate reality terrain. There are many methods to model terrain, such as fractal geometry technology, based on real terrain data synthesis and so on. Only geometry of three-dimensional terrain is more reality, and we decorate the terrain with some other technology, then we get better result.First of all, fractal geometry modeling terrain technology is introduced, we focus on Perlin noise, the improved algorithm based on Perlin noise can model some unique terrain, which is the foundation of generating reality terrain. Then, terrain erosion technology is delivered, which simulate some nature phenomena to erode terrain. The simulation can make terrain abundant in details. Last, terrain rendering and speedup terrain rendering technology are introduced, through multiple texture blending and terrain lighting add more detail. The use of visible area determination and LOD technology can increase the frame rate of terrain rendering, because complex compute decrease the performance of CPU.We use improved algorithm based on Perlin noise to model terrain here, then we use terrain erosion technology to add more detail. We design a system of 3D terrain edit by together terrain layout and terrain amending, which can generate many types terrain.In the terrain edit system, we use the method based on the filter to edit terrain. For example, the function of the filter Terrace is to make terrain be a terrace terrain. Although the controllable of the method based on filter is low, the effect of terrain that is edited by the method based on filter is very good, we also adopt it. The terrain amending in the system is used to edit the local segment. There are different textures on the different altitude terrain with multiple texture blending. Furthermore, the use of back face culling and Geomipmap technology in the system can speed up graphic rendering. |
