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1、摘要本文在第二章中,引入三次Bernstein多项式调配函数,定义了带形状参数的四次多项式基函数,运用线性组合方法构造了基,称为样条基。为了使构造的基函数满足连续性以及规范性,利用连续性以及规范性的关系等式求得待定系数,将待定系数代回到扩展基中并进一步分析扩展基的性质。再由扩展基定义了一种含形状参数的B样条曲线称之为样条曲线,由于曲线带有形状参数,使得扩展的曲线具备形状可调性。也就意味着在给定控制顶点的情况下选择形状参数的不同取值,可以改变样条曲线的曲线形状。在样条曲线的曲线设计中,针对不同的的取值,对构造曲线图像进行比较,可以发现形状
2、参数不同取值下的差异性。另外,本文在第三章中构造了带形状参数的三次三角均匀B样条曲线,首先引入一个三次三角基函数,对这个基函数进行扩展后运用线性组合的方法构造了三次三角均匀B样条曲线的扩展基,为保证扩展基的连续性以及规范性,假设扩展基具备连续性以及规范性求出待定系数关于形状参数的等式,并分析扩展基的性质,通过扩展基运用分段曲线构造定义了样条曲线,并对构造的样条曲线的性质进行分析。在曲线设计中,在给定控制顶点的情况下选取形状参数的不同取值,会改变曲线形状,并利用样条曲线构造了样条曲线的旋转面。关键词:形状参数;连续性;B样条曲线;三角B样
3、条曲线27AbstractInthesecondchapter,wedefinethequadraticpolynomialbasisfunctionwithshapeparameters,whichisaspecialcasewithcubicBernsteinbasisfunctionandquadraticbasis.Inordertomakethebasisfunctionoftheconstructsatisfythecontinuity,thecoefficientsofthelinearcombinationareobta
4、inedbyinversecalculation,andtheexpressionoftheextensionbasisisobtainedandthepropertiesoftheextensionbasisareanalyzed.The-B-splinecurvewithshapeparameterisdefinedbytheextensionbasisandiscalledtheB-splinecurve,whichisstructurallythesameasthecubicB-splinecurve,sothattheexte
5、ndedcurvehasshape-adjustableproperties.Thatis,inthecaseofagivencontroloftheverticesoftheselectedshapeparametersofdifferentvalues,youcanchangethecurveshapebychangingshapeparameters.InthecurvedesignoftheB-splinecurve,thedifferencecanbefoundbycomparingthevaluesofthedifferen
6、tandthetectoniccurves.Inthethirdchapter,weconstructacubictrigonometricuniformB-splinecurvewithshapeparameter.First,wedefineanextendedcubictrigonometricbasisfunction,anduselinearcombinationtoconstructtheextensionbasisofcubictrigonometricuniformB-splinecurve.Inordertoensur
7、ethecontinuityandnormalityoftheextendedbasis,theundeterminedcoefficientsofthelinearcombinationareobtained,theexpressionoftheextensionbasisisobtainedandthepropertiesoftheextensionbasisareobtained.Thenthesplinecurveisdefinedbytheextensionbasis,andthepropertiesoftheconstruc
8、ted-B-splinecurveareanalyzed.Inthecurvedesign,theshapeofthecurveischangedwiththedifferentvaluesofthesha