Interactive Real-time Rendering Of Natural Scenes To Achieve

Real-time rendering and interaction technology make the simulation of natural scenes realistic. The field about how to render real-time natural scenes interactively has been research highlight. Although we get much works, most of them were focused on the geometry of the grass, only a little of them are about the interaction and the light or shadow. Until 2006, Kevin Boulanger simulated real-time natural scenes with dynamic light. The scenes simulated by Kevin are very realistic, but he doesn't handle interaction effects. The interaction effects currently realized are still not thoroughly, there is still much work to do. Besides, many natural objects, for example grass, haven't a uniform modeling method. None of the existing modeling methods are perfect. Accordingly, how to rendering a natural scene, real-time, realistic and interactive, is the problem the research aims to solve.Firstly, based on the graphical engine of irrlicht, the thesis designs a grass-rendering system. The system includes the module of grass modeling, interaction, shadow of grass and so on. The following parts will introduce them in detail.Secondly, the thesis realizes the level of detail (LOD) of the grassland. As we know, although there are many ways to model the grass, for the whole grassland, there requires much data, and some of the data is not a must. Therefore, the thesis divides the grassland into three parts, according to the distance between the eye and the grass in the scene. The grass of the part that is closest to the eye is modeled by the method based on the theory of the improved particle system. The grass is verified to be realistic by our experiment, and it can be interacted easily. To reduce the geometry information but not affect the visual of the scene, the grass of the second part is modeled by simplified star billboard.Thirdly, based on the grass modeled by the theory of the improved particle system, an improved procedural approach for simulating the dynamic process of treading grass is designed and implemented. To simulate the process of treading grass, there are two means: the procedural approach and the physical approach. The former simulates the process by the experienced formula, so it is adapted to the real-time application. The latter can simulate realistic effect by the exactly physical formula, but much time is needed. So the thesis adapts the procedural approach for the requirement of real-time. Besides, we consider the conflict in grasses. The result of experiment shows that the approach can simulate the process of grass treading effectively and realistically.Finally, based on the algorithm of real-time shadow rendering for large-scale virtual environments, we realize the shadow of the grassland. Instead of using a big shadow map for the whole grassland, the algorithm uses several small shadow maps. It requires less texture memory and improves the quality of shadow.