Non-Photorealistic Computer Graphics Library

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Proceedings Between Photo-realism and Non-Photorealistic Rednering - Modeling Urban Areas for Real Time VR

Author(s): G√ľnter Pomaska.
Proceedings: International Workshop on Vision Techniques applied to the Rehabilitation of City Centres, October, 2004.
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Non-photo realistic rendering techniques generally admits as painterly rendering, line art rendering, computer sketching and half toning. These techniques are widely used for producing stylized artificially looking drawings. Computer models in architecture are often targeted to photo-realism. Rendering techniques like ray tracing or radiosity can provide realistic looking results. The quality depends on the definition of material, light and environment. Applying real time virtual reality is still a compromise between navigation speed and photo-realism. Using image textures from photos, rectifications or orthophotos, and mapping them to a generalized geometry does not give sufficient results. The first impression of a so-called photo realistic model might be nice. A closer look displays discontinuities in shadows, radiometric distortions or perspective errors. Objects occur in the scenery, which should not be there. Photo realistic computer models provided in this way are only useable for visualization. Improved solutions exist in the use of a pre-processor, preparing the CAD model for good quality rendering and high-speed interactive navigation. Taking into consideration that non-photo realistic rendering techniques are used in real time VR as well, we should ask the question why trying photo-realism? Under architectural modeling, we define a technique that represents a building with a certain degree of abstraction but still providing the characteristics of the buildings. This contribution reports about modeling an urban area by converting CAD models into a VR data structure. It is designed for PC workstations and Web. The fourth dimension is the time, the epochs of the emergence of buildings and site construction.

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