Abstract

In computer graphics, 3D objects are projected onto the viewing plane in either parallel or perspective mode. As far as perspective projection is concerned, traditional rendering engines are designed to carry out only linear planar projections, as in OpenGL. But what if we expect to get certain distorted views? For instance, we see distorted scenes when we look through a rain drop on the windshield. When we play video games, we also might want to have a pair of "magic" lenses that let us see a deformed virtual world. Currently the nonlinear projections and implementations still remain largely unexplored in 3D graphic environments. In the first part of this thesis, several nonlinear projection models are investigated and an algorithm is presented to apply these models to perform nonlinear perspective projections and 3D view deformations in real time. Wide-angle lenses are often used to take landscape photos and they are also useful for pictures of large groups of people, but usually they introduce "barrel" distortions into photos. Researches have been done to remove these distortions from the images. However, for some artistic reasons people may want to keep them. So can we simulate this effect in the computer graphics visual world? I developed a polynomial approximation model and applied the real-time algorithm introduced in the first part of the thesis to achieve the barrel distortion effect of a wide- angle lens. An experimental system based on the above algorithm and models has been developed to navigate 3D world with various deformed views.