Large-scale Forest Scenario Modeling And Rendering Of Key Technologies And Realization

Modeling and rendering of large scale natural scenes has always been an important research field in computer graphics in recent years. It played an essential part in whether 3D-games, special effects in film, landscape designing, or military simulation. Modeling and rendering of tree and forest has also been a focus in this area. Rendering of large area of forest real-time and generating real-time animation of trees swaying in the wind can increase the reality of the whole virtual scene. Therefore, this dissertation dedicated to designing a modeling method of large scale forest, and a real-time animation simulation method of trees swaying in the wind.We analyzed various related technologies of modeling and representation in the field of vegetation simulation, including detailed representations, global representations, multi-scale representations of trees and grass and technologies of generating interactive animation for trees. We analyzed the advantages and disadvantages for applications of these technologies in many aspects such as realism and efficiency.First, this dissertation implemented a method of modeling a single tree base on the level structure of the tree. Compare to the old method, we added new ways in both branch structure organizing and leaf structure simulation.Then, with the help of management strategies of large scale scene and instance technology in our method, we designed a mixed modeling method for large scale forest. In this method, we also proposed a new simple LOD transition strategy based on the level structure of the tree to achieve real time rendering of large scale forest.Finally, we proposed a method of generating real time interactive animation of trees, based on precomputing deformation of trees, key frame selection to synthesize the main part of the animation and real time computing of compensation. We use the simple two-dimensional vector field to simulate the real time wind field. We precomputed the deformation position of the tree in the wind by using the physical model of"Stiffness coefficient- rotate angle". In the animation synthesis stage, we divided the whole animation into"in the wind"and"after the wind"two section, and used different key frame selection strategies to generate the animation. At last, we used computing of compensation to fix key frame animation and increase the accuracy and diversity of the animation.