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Background

  Non-photorealistic rendering (NPR) techniques vary greatly in their level of abstraction. In technical illustrations, shape information is valued above realism and aesthetics. Therefore a high level of abstraction, like the images in Figure 2.1, would be inappropriate. As summarized in Table 2.1, no work has been done which uses the ideas and techniques of technical illustrators to generate not only 2D technical illustrations but also to provide an interactive environment for viewing 3D models as 3D technical illustrations. A review of the papers involving NPR or other illustration techniques used in computer graphics reveals that most papers can be partitioned into two categories: those which generate only aesthetic images and those whose purpose is to convey shape and structure. The images in the latter category may themselves be aesthetically pleasing, but this is a side effect rather than a primary goal. These papers can also be further divided into those that generate a single image and those that are part of an interactive or animation system. Human perception and recognition studies [2,4,7] are another valuable source of information. These perception studies suggest an explanation of why line drawings, like technical illustrations, are enough for object recognition and provide a hint as to why they may also provide shape information.



   
Table 2.1: Summary of non-photorealistic and other computer graphics papers.



 
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Next: Paint Programs and One-Shot Up: Interactive Non-photorealistic Technical Illustration Previous: Introduction