Journal of Software, Vol 7, No 6 (2012), 1219-1226, Jun 2012
doi:10.4304/jsw.7.6.1219-1226

Convexity Conditions for Parameterized Surfaces

Kui Fang, Lu-Ming Shen, Xiang-Yang Xu, Jing Song

Abstract


Based on a geometrical method, the internal relationships between locally parameterized curves and the local parameterized surfaces are analyzed. A necessary and sufficient condition is derived for the local convexity of parameterized surfaces and functional surfaces. A criterion for local convexity (concavity) of parameterized surfaces is found, also, the criterion condition of binary function convex surfaces is obtained. Finally, the relationships between a globally parameterized curves surfaces is discussed, a necessary condition is presented for the global convexity of parameterized surfaces , and it is proved that locally convex parameterized surfaces are also globally convex.



Keywords


local convexity, global convexity, gauss curvature, the second fundamental form

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