Step length in forward differencing for curved surface display
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Principles and basic algorithms for evaluating polynomial functions by Forward Differencing (FD) and Adaptive Forward Differencing (AFD) are presented. Both techniques are used nowadays in scanning/display algorithms for parameteric polynomial surfaces by generating and displaying a set of points. Constraints to be put on such a set of points are made explicit. One FD and two AFD surface-scanning/display algorithms presented in literature are evaluated in terms of these constraints. The FD algorithm is proved to be valid, but the AFD algorithms are shown to be incorrect. A valid AFD algorithm is presented.
Key wordsScanning/display algorithm Forward differencing Parametric polynomial surface
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