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PhD Thesis Art-based Modeling and Rendering for Computer Graphics

Author(s): Lee Markosian.
PhD Thesis: Department of Computer Science, Brown University, 2000.
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Over the centuries artists and illustrators have developed techniques to effectively convey visual information. In this dissertation we develop the idea that we can apply these techniques to increase the expressive power of 3D computer graphics. This leads us to seek to build a unified free-form modeling system with which a designer can amplify her skills with pencil and paper to model both the geometry and stylized look of virtual scenes. In part I we first develop algorithms for rendering finely tessellated smooth surfaces in the style of simple line drawings, and at interactive rates. We next develop a procedural texture framework that lets us divide a model into distinct regions, with each rendered according to what it represents (bricks on the walls of a castle, say, but wood planks on the drawbridge). We then use this framework to develop two new classes of rendering algorithms { one class performs simple hatched shading, the other adopts techniques of the children's book illustrator Dr. Seuss (and others) to render fur, grass and trees in a stylized manner. In part II we focus on the problem of modeling a scene's geometry through an interface that leverages an artist's 2D drawing skills. We begin with a new technique for constructing 3D curves from 2D input: The user draws a curve and its shadow as both would appear from a given viewpoint, and the system computes the corresponding 3D curve. We next describe a new algorithm for computing a free-form surface that smoothly fits over a collection of \primitives" such as generalized cylinders or other \swept" objects. Our intention is to integrate the two techniques so that an artist can quickly sketch such primitives with the help of the first technique, then oversketch them with the second technique to produce the desired free-form surface. The natural next step is to integrate the various parts into a single system for sketching both 3D shapes and the stylized rendering algorithms used to depict them.

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