3D Scenery Modelling And Its Rendering Method

Recently, With the development of the photo-realistic display technology of computer graphics and the computer hardware, it's probable and convenient for us to describe the three dimensional world. What is more, the requirement of all kinds of fields to computer graphics technology is not confined to the plain and still graphics. With the development of computer simulation, virtual reality, three-dimensioned game, it's more important for the 3D scenery to build and real-timely render.The paper, which is based on the project of National Science Fund -Behavior-Characteristic modeling for Distributed & Interactive 3D Scenery and the project the Development of Distributed and Interactive 3D Simulation Platform, chiefly research the modeling of 3D scenery and the method to real-timely rending the scenery. The paper mainly involved four parts: the generation of digital terrain model, the rebuilding of 3D terrain, the method to real-time rendering 3D terrain, the technology of the photo-realistic terrain generation.In the first chapter, there mainly introduce the source, the research purpose and the significance of the project. The key technologies involved in the paper are introduced, too.In the second chapter, there provide two methods to generate terrain model. One is based on bitmap. This way is in light of the mapping between gray levels of the bitmap and the height of the terrain. In other words, the minimum gray point is the lowest terrain and the maximum gray point is the summit. The other is based on contour line. The way is that first editing the contour line, then saving these heights, finally depending on linear calculating middle value, thus getting the height of every mesh point, and the 3D terrain model.In the third chapter, there principally introduce the method of ground objects model generation. On the grounds of the relation of the ground objects model and the terrain model, we can assort them into two kinds. One is inIIIrelation to the terrain, such as river, lake, artificial hill etc. The other is not in relation to the terrain, for example tree, simple building etc. As for the first ground objects model, I expound and realize natural piling algorithm; as for the second, the paper adopt the billboard algorithm that use 2D image in place of 3D models.In the forth chapter, there introduce the real-time rendering method of terrain. When we generate quit photo-realistic scenery, but because of the complication of terrain, it's impossible to realize the real-time rendering. We must simplify the complication of terrain resting on its characteristic. The LOD technology was proposed in this environment. In the paper I propose and realize the LOD based on transitional band. Quad tree algorithm and ROAM algorithm are depicted in detail.In fifth chapter, there introduce the generation technology of photo-realistic scenery. If we want to render out photo-realistic scenery, we should consider these circumstance: the terrain surface with more detail, rendering ground vegetation, even all sorts of weather effects. All of these can make scene more natural, more real. This chapter chiefly introduces the technology of sky generation, lighting, material, fog, texture, the detail of terrain surface.The sixth chapter summarizes the paper, and prospects the next work.