Christoph Hornung

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An analytical method to determine the visible parts of parametrically defined tensor-product surfaces is described. All vistbility calculations are strictly oriented on the (u, u)-parameter plane. This leads to substantial advantages over visibility algorithms based on the approximation of curved surfaces by sets of planar polygons. The new algorithm allows(More)
-Today's graphics standard for the rendering of scenes with illumination and reflection is defined by PHIGS+. PEX is a proposal to integrate that functionality into the window environment of X. This paper first describes the lighting and shading models of PHIGS+/PEX. Then a comparison of the different shading methods follows. At last, a new shading method,(More)
A personal-computer-based architecture that uses graphics methods to improve cooperative multimedia work over integrated services digital networks (ISDNs) is discussed. The system supports cooperative multimedia work by providing real-time video, graphics, and speech. The system requirements, components, and general architecture are considered, as is the(More)