3D自由曲线的绘制及智能修改算法

目前有关曲线及曲面的生成，大量的研究致力于从控点和节点的设置到曲率、切线矢量进一步精确的调整．然而其繁琐的几何参数计算、复杂的数学概念局限了设计者的使用，尤其他们更不适合早期的概念设计。此研究描述了基于笔输入的自由3D曲线的绘制．识别及直观的修改算法，此算法支持任意3D自由曲线的绘制，通过优化的采样机制自动识别产生适应性的B样条逼近曲线，它扩展了基于约束的曲线的生成方法，进而提出的简单的局部修改技术，引入了比例因子及区域间距的控制，有效的解决了曲线的光滑性，并通过实践检验了它们的高效性。

Free form 3D curve sketching and intelligent oversketching algorithm

At current most researches of surface and curve modeling dedicate to from the setting control points and knots to the sophisticatedly adjusting tangent vector and curvature features. However, this cumbersome computation ofgeometric parameters and complex mathematic knowledge make it difficult for designer to use, especially it is not suitable for conceptual modeling stage. A free-form 3D curve recognition and oversketching algorithm which based on free-hand sketching input are described. This algorithm supports arbitrary 3D curve drawing, and through the optimal sampling technique it automatically recognizes, as a result the adaptive B spline curve is approximated, in a sense it further extends the method of constraint-based curve generation. Furthermore, an effective local modification method is proposed using simple oversketching, in order to improve the smoothness of transition interval scale factor and transition interval threshold features are introduced, in the end a series of tested results indicate this efficiency.