Outdoor Scenes, Realistic Drawing

It's a challenging work to simulate global illumination in outdoor scenes, which usually have large scales and lit directly by both sunlight and skylight. We present a view dependent rendering algorithm for simulating the illumination effects in outdoor scenes. The algorithm simulates the effects of not only the illumination of sunlight and skylight, but also the energy exchange among scene objects to have inter-reflection. We only render the visible parts in a picture to avoid the redundant computation of invisible objects, which usually are dominant parts in outdoor scenes, at a fixed view field. In the meantime, we decide the sampling density according to the resolution of the final picture and the energy exchange among different areas to assure all the sampling is necessary.In Chapter 1, we first describe the meaning of realistic rendering in computer graphics and introduce some common rendering techniques. Secondly, we discuss the properties and importance of outdoor scene rendering. Finally, we give out the framework of the thesis and the algorithm we are going to discuss.In Chapter 2, we discuss the rendering of outdoor scenes. Mainly introduce the modeling methods of sunlight and skylight and current works on outdoor scene rendering. We introduce some shadow algorithms at last as shadows play a key role to make a picture realistic.In Chapter 3, we propose a view dependent algorithm to render outdoor scenes. We simplify the rendering equation based on our purpose. And use effective strategy to choose sampling points. The computation of skylight and the reflection energy gathering are processed at the same time in our algorithm.In Chapter 4, we present some important data structures and some aspects that should be noticed when the algorithm is realized. We also present some rendering results to verify our algorithm.The last chapter is the conclusion of the thesis and the future work.