Real Time Reflection And Dynamic Water Rendering In Interactive Architecture Roaming System

With the rapid increase in the computer processing power on both CPU and GPU, and progress in the theory of computer graphics, virtual environment can now be rendered in realtime on modern PC to achieve close to photo realistic visual quality. This greatly expands the application areas of virtual reality. Interactive architecture roaming is such an emerging area. Different from conventional game rendering, architecture roaming is more demanding on visual quality. The requirement is to achieve close to photo quality rendering of the virtual environment. As such, much effort should be endeavored on lighting and representation of material.Based on Irrlicht, which is an open source 3D engine, we propose a feasible solution for interactive architecture roaming. The key is to adopt offline generation of lightmap in the interactive environment, which can have very realistic visual quality. On the other hand, we expand the Irrlicht functions by implementing a planar reflection scheme and dynamic water rendering solution.In virtual reality, reflection has the property of view point dependency as well as dependent on the global environment, which can not be emulated by the use of lightmap. On the other hand, GPU rendering pipeline is only suitable of processing object-oriented local information, which makes it difficult for the reflection effect. For curved or small objects, environment mapping can be used. However, this method is not suitable for large area planar reflection. Under the assumption of no multiple inter-reflections, we propose the render to texture (RTT) method, which can dynamically generate reflection texture. The projection matrix is updated in realtime, and the scene is dynamically project with respect to the reflection surface, thus providing a solution to the large area planar reflection.In interactive architecture roaming, dynamic water surface simulation is critical, especially to the outdoor environment. In Irrlicht, the existing water surface emulation approach only consists of simple waves with combination of two texture images. The result is thus far from convincing, and not suitable for demanding applications such as interactive architecture roaming. In this thesis, we use shader language to program the GPU to achieve shallow flat water effect. We adopt Gestner wave formula for wave synthesis. Normal map is used to represent the ripples on the water surface. In contrast to the bump mapping method, more realism is added by the ripples so that the scene is more convincing. In the meantime, we use the render to texture technique to simulate the reflection on the water surface. Further, the Fresnel weight parameter is represented in the alpha channel of the texture to simplify the combination of reflection and refraction. This can best trade-off the rendering quality of the Fresnel effect and rendering efficiency.