Large-scale Outdoor Scenes Real-time Photorealistic Rendering Engine Architecture And Realization

Rendering large area of realistic outdoor scene is important in many fields of computer graphics, such as real time video games, virtual reality based education program and virtual exhibition applications. This thesis presents the design and implementation of a high level engine focused on real time rendering of large-scale outdoor scene.This thesis consists 3 main parts.The first part is a short introduction focused on the project background, the state of the art presentation of related areas as well as a detailed description of important technology used extensively in the architecture implementation and algorithm optimization process. Then, we present the main research contribution of this thesis. And finally is the overall organization of our thesis in details.The second part is a detailed description of the architecture and implementation of a high level framework call DME. DMF is an object-oriented, plug-in based middle ware designed to facilitate the process of real time rendering of outdoor scenes. DMF is engineered in a Test Driven Development (TDD) way. So we first introduce our implementation of a light weight unit test component. Then we introduce the core component and the scripting component. And finally we demonstrate the design and implementation of a real time collaboration editor prototype built on top of DMEThe third part presents our two optimization algorithms designed to accelerate the rendering of outdoor nature elements including dynamic water and forest. First is a GPGPU based algorithm to solve and render 2d wave equation. The emphasis is on the development of acceleration strategy to put the numeric solver of partial differential equation and the real time rendering of wave strip entirely on GPU. By using the latest shader model 3.0 features- Vertex texture fetch, the transfer of computation results from GPU to CPU is avoided, thus a considerable performance gain is achieved. We also discuss the potential improvements using the upcoming shader model 4.0 GPU.Second is a novel hybrid rendering system for forest scene that solves the classic problem of degraded quality of image-based representations at close distances by building an impostor rendering system on top of a full, geometry-based, forest rendering system. This enables almost imperceptible switching between the two representations. By using a novel texture atlas based impostor algorithm, a considerable performance gain is achieved. This system is embedded in a real world natural scene simulation application for testing purpose. The results demonstrate this system capable of rendering dense forest with the visual realism of a high-resolution geometry rendering system, but only at a fraction of the rendering cost.