共查询到18条相似文献,搜索用时 187 毫秒
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基于几何特性的三次均匀B样条曲线构造描述 总被引:7,自引:0,他引:7
基于B样条曲线是分段的Bézier曲线段的集合这一数学特性,通过剖析三次均匀B样条曲线的数学表达及其几何意义,由曲线的几何特性给出了各曲线段Bézier点的几何表示。每段B样条曲线段(三次Bézier曲线段)对应的4个Bézier特征顶点,可以导出该曲线段的B样条基函数。依此为基础,描述了三次均匀B样条曲线构造的原理和过程,并给出了不同曲线段数情况下曲线特征构造和插值构造的相关公式。 相似文献
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由于多电子枪显象管玻壳是一个变厚度组合壳体,很难用板壳经典理论进行求解,所以在设计九电子枪彩管玻壳时用有限元方法预先知道该玻壳的应力分布,通过修改设计参数,使九电子枪彩管玻壳能满足强度要求,在设计玻屏时采用非均匀有理B样条的曲面分析方法,锥体采用四条组合的非均匀有理B样条曲线旋转一周得到,本设计实现了玻屏表面外形和曲率变化及玻壳结构设计的全参数化,提高了玻壳的设计效率,本还给出了计算玻壳外型的公式和一些技术参数。计算机仿真结果表明:42英寸九电子枪彩色无支撑CRT的玻壳既能满足强度要求,又具有好的视觉效果。 相似文献
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B样条曲线的小波光顺法 总被引:10,自引:1,他引:9
本文研究了B样条曲线的小波光顺法。首先介绍了利用准均匀B样条曲线逼近具有任意节点矢量的B样条曲线的方法,从而将任意B样条曲线转化为多分辨率表示,进而提出了基于小波的曲线光顺误差控制算法。小波光顺法在光顺曲线的同时具有减少控制顶点的作用,兼具简单性和通用性的优点。 相似文献
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基于Haar小波分解的快速曲线重构 总被引:1,自引:0,他引:1
采用Haar小波分解构造误差驱动的曲线数据压缩算法,对求得的少量重要数据点。运用保型性好计算速度快的通用参数化曲线插值方法,最终求得满足要求的三次B样条曲线,本文算法适用于大量密集数据点的快速曲线重构。 相似文献
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本文在分析张量积有理B样条蒙皮面曲面方法不足的基础上,给出了用截面外形设计原理构造有理蒙皮曲面、回转曲面及扫掠曲面的方法,并提出了对G~1连续的有理曲线进行重新参数化使其达到C~1连续的方法。文中的实例表明用该方法能够产生满足设计要求的参数曲面。 相似文献
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与给定多边形相切的C 3连续B3样条曲线 总被引:6,自引:1,他引:5
描述了一种与给定多边形相切的B3样条曲线的算法。在算法中,所有的B3样条曲线的控制点可以通过对多边形的顶点简单计算产生,所构造的曲线对多边形具有保形性,曲线可以局部修改,最后给出了两个算例。 相似文献
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Gang Xu Yufan Zhu Lishan Deng Guozhao Wang Bojian Li Kin-chuen Hui 《计算机、材料和连续体(英文)》2019,58(3):879-892
In this paper, we propose an efficient method to construct energy-minimizing B-spline curves by using discrete mask method. The linear relations between control points are firstly derived for different energy-minimization problems, then the construction of B-spline curve with minimal internal energy can be addressed by solving a sparse linear system. The existence and uniqueness of the solution for the linear system are also proved. Experimental results show the efficiency of the proposed approach, and its application in G1 blending curve construction is also presented. 相似文献
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基于半正交B样条小波的任意控制顶点数曲线光顺 总被引:2,自引:0,他引:2
目前,小波分析应用于逆向工程时,对控制顶点有特殊要求,只能处理2j r个控制顶点的图形,为此提出了一种可以光顺任意控制顶点B样条曲线的小波分析新方法。在介绍B样条定义的基础上,从小波分析的定义出发,用严格的数学证明推导了任意控制顶点曲线的小波分解与重构具体算法。最后,该算法成功应用于B样条曲线的小波光顺,实例表明,该算法准确、结果稳定,效率理想。 相似文献
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等距曲线的拓扑结构是等距算法中的核心因素之一。该文以B样条曲线为例,给出了一种基于关键点的等距算法。它应用了自适应离散等手段并给出了关键点的求解方法,同时利用关键点确定等距线各个分段的取舍,从而有效地去除自交的情况,使得计算出的等距曲线有着正确的拓扑结构。该文的算法已应用于商业软件OpenCAD中。 相似文献
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The topic of representing the offset of a 2D B-spline curve in the same form has been a topic of research for a long time, and it has many industrial applications, especially in NC tool path generation for pocketing. For B-spline tool paths, it is often required that the tool paths have fewer control points, lower base function degree, and the approximation error is guaranteed within a given tolerance over the entire curve. However, the existing methods utilising global error control approximate the offsets of 2D free-form curves with high function degree and many control points. Although these offsets are useful in computer-aided design, they are inappropriate for the use of CNC machining. To address the problems in order to generate high quality B-spline tool paths, this original work formulates an error function of the offset approximation and then constructs a NURBS curve to globally bound the errors. By checking the maximum coefficient of the bounding curve, the upper bound of all the approximated offset errors is found and the errors can be reduced by segmenting the curve at appropriate knot values. The proposed new approach is more efficient, and the resulting offset approximations are more accurate, with fewer control points and lower function degree. It is useful to generate B-spline tool paths for CNC pocketing, which have the potential for other applications in industry. 相似文献
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WANG Zheng WU Hu SHI Ya-feng Wang Hong-boDepartment of Aeroengine Northwestern Polytechnic University Xi′an China Unit of PLA Anshan 《国际设备工程与管理》2009,(1)
A new method for design of turbomachinery blades is presented. The parameters of a compressor blade are created from the Computational Fluid Dynamics (CFD) software CFX-BladeGen, and are inputted to the Computer Aided Design (CAD) software UG for building a curve surface model to create an entity model in UG. The result shows that the blade model is favorable from the entity effect and reflection analysis and the model process is useful for the CAD model creation of turbomachinery blades. 相似文献