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1.
曲面激光密集测量三维数据的三角片逼近方法   总被引:10,自引:2,他引:8  
本文以激光-机器视觉测量方法得到的曲面数据云为基础,探讨了曲面密集三维散乱点群数据的几何建模方法,根据激光测量方法和三维点群分布的特点,建立了恰当的数据结构在计算机中表示散乱点群。由八叉树空间分割原理对密集散乱点群进行空间分割,建立八叉树拓扑关系。由八叉树空间分割原理对密集散乱点群进行空间分割,建立八叉树拓扑关系,显著加快了任意点的搜寻速度。采用万有引力定律计算三角片顶点坐标,由此实现散乱点数据的  相似文献   

2.
散乱数据点三角剖分方法综述   总被引:27,自引:2,他引:25  
构造散乱数据插值曲面首先必须对散乱数据点实行三角剖分。本文简要阐述三角剖分的基本概念。并按优化准则将现有的各种三角剖分方法进行分类比较,为建立更好的凸域三角剖分算法提供依据,并为解决复杂多边形区域散乱数据点三角剖分奠定基础。  相似文献   

3.
葛金辉  赵江  何甲兴 《工程数学学报》2003,20(6):140-142,125
利用B样条曲面表示初始逼近曲面,利用三次B样条曲线优化曲面,实现了散乱数据的曲面重构,算例表明,算法简单易行,逼近效果良好。  相似文献   

4.
在逆向工程中,对基于散乱数据点的曲线重建研究有着重要的意义。曲线可用线段基元逼近。提出使用成长型神经网络以线段为基元的曲线重建新算法。给定某一曲线的散乱点集和一初始折线,新算法优化折线上的顶点位置,使折线更好地逼近散乱点;持续分裂折线上活动性强的顶点和删除活动性最弱的顶点,使折线上顶点的分布更符合散乱点数据的概率分布。实验结果表明,新算法能够取得良好的曲线重建效果。  相似文献   

5.
空间三角形网格优化算法   总被引:3,自引:0,他引:3  
本文提出了空间三角形网格的优化算法,给定一组三维散乱点集和一个初始三角形网格,对三角形网格顶点位置优化和应用三角片局部细分方法,使该网格能更好的逼近三维散乱点,提高了网格对散乱点的逼近精度。  相似文献   

6.
本文讨论了雨量预报方法的评价问题。给出了散乱数据拟合的若干方法及误差确定方法,同时在顾及公众反应的情形下考虑了评价准则,最后针对评阅中发现的一些问题作了评述。  相似文献   

7.
基于散乱数据点集构造三角插值曲面的方法,在CAD/CAM、科学计算可视化、图像处理等领域有着广泛的应用。本文介绍一种基于遥感图像散乱数据点的三角曲面片插值构造方法。该方法通过在遥感图像上选取局部极值点来构成平面散乱数据点集,并在此基础上进行三角剖分、优化和三角插值曲面构造。此方法在海洋遥感图像多尺度分解处理应用中取得了较为理想的结果。  相似文献   

8.
平面域任意散乱点自动三角化的研究   总被引:15,自引:2,他引:13  
基于平面区域内散乱点的Delaunay三角剖分准则,本文提出一种适用于平面区域内任意散乱点的通用三角化算法。文中详述了三角化的具体实现过程和在三角化过程中可能出现的各种“接触”情况,给出了程序流程图。最后给出实例并把此种方法成功地运用到三维光学数字成像系统。  相似文献   

9.
探讨了曲面密集三维散乱点数据的三角网格智能重建方法。建立了基于自组织特征映射神经网络的三角网格构建模型。该模型利用神经元对曲面散乱点的学习和训练来模拟曲面上的点与点之间的内在关系,结点连接权矢量集作为对散乱点集的工程近似化并重构曲面样本点的内在拓扑关系,实现曲面密集三维散乱点数据的自组织压缩。按六角形阵列侧抑制邻区训练调整网络神经元权重矢量,使网络输出层结点呈六角形阵列分布,可实现测量点集压缩后的Delaunay三角逼近剖分。计算机仿真实验表明,所建神经网络模型可以实现期望规模和精度的三角网格剖分并有效保持原数据点集的拓扑特征。  相似文献   

10.
给出了平面中线上分布的散乱数据点的自然样条的局部插值基,并证明了这个基等价于自然样条的截幂基,给出了这些基函数的局部紧支集。做出了算法并且给出了算例,效果良好。  相似文献   

11.
针对传统的线性插值算法存在的边缘模糊问题,本文提出一种新算法.首先采用距离平方反比的插值方法在插值点邻域内计算水平、垂直和对角三个方向共6个插值,然后以插值距离和方向梯度构造权重,进行数据融合获得最终插值.该算法既考虑了插值距离因素,又考虑了插值方向梯度信息,有效地保护插值图像的边缘和纹理信息.实验结果表明,该算法的插值图像比传统的双线性插值法均方误差降低而平均梯度增加,是一种提高插值图像分辨率的有效方法.  相似文献   

12.
一类加权有理三次样条的区域控制   总被引:2,自引:0,他引:2  
将插值曲线约束于给定的区域之内是曲线形状控制中的重要问题.本文利用分母为二次的有理三次插值样条和仅基于函数值的有理三次插值样条构造了一类加权有理三次插值样条函数,这类新的插值样条中含有权系数,因而增加了处理问题的灵活性,给约束控制带来了方便.给出了将该种插值曲线约束于给定的折线、二次曲线之上、之下或之间的充分条件及将其约束于给定折线之上、之下或之间的充分必要条件.证明了满足约束条件的加权有理样条的存在性.  相似文献   

13.
The dual-reciprocity boundary-element method is a very powerful technique for solving general elliptic equations of the type 2u=b. In this method, a series of interpolation functions is used to approximate b in order to convert the associated domain integral, which it is necessary to evaluate in a traditional boundary-element analysis, into boundary integrals only. Hence the choice of interpolation functions has direct effects on the numerical results. According to Partridge and Brebbia, the adoption of a comparatively simple form of interpolation function gives the best results. Unfortunately, when b contains partial derivatives of the unknown function u(x, y), the adoption of such a type of interpolation function inevitably leads to the creation of singularities on all boundary and internal nodes used in a dual-reciprocity boundary-element analysis, as was pointed out by Zhu and Zhang in 1992. To avoid this problem, a functional transformation, which applies only to linear governing equations, can be employed to eliminate these derivative terms and thus to obtain better numerical results. In this paper, two new interpolation functions are proposed and examined; they are proven to be generally applicable and satisfactory.  相似文献   

14.
We develop an acceleration method for material‐dominated calculations based on phase‐space simplicial interpolation of the relevant material‐response functions. This process of interpolation constitutes an approximation scheme by which an exact material‐response function is replaced by a sequence of approximating response functions. The terms in the sequence are increasingly accurate, thus ensuring the convergence of the overall solution. The acceleration ratio depends on the dimensionality, the complexity of the deformation, the time‐step size, and the fineness of the phase‐space interpolation. We ascertain these trade‐offs analytically and by recourse to selected numerical tests. The numerical examples with piecewise‐quadratic interpolation in phase space confirm the analytical estimates. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

15.
In this paper, we propose a novel image interpolation method by using Gaussian-Sinc automatic interpolators with partition of unity property. A comprehensive comparison is made with classical image interpolation methods, such as the bicubic interpolation, Lanczos interpolation, cubic Schaum interpolation, cubic B-spline interpolation and cubic Moms interpolation. The experimental results show the effectiveness of the improved image interpolation method via some image quality metrics such as PSNR and SSIM.  相似文献   

16.
We present an interpolation method for efficient approximation of parametrized functions. The method recognizes and exploits the low‐dimensional manifold structure of the parametrized functions to provide good approximation. Basic ingredients include a specific problem‐dependent basis set defining a low‐dimensional representation of the parametrized functions, and a set of ‘best interpolation points’ capturing the spatial‐parameter variation of the parametrized functions. The best interpolation points are defined as solution of a least‐squares minimization problem which can be solved efficiently using standard optimization algorithms. The approximation is then determined from the basis set and the best interpolation points through an inexpensive and stable interpolation procedure. In addition, an a posteriori error estimator is introduced to quantify the approximation error and requires little additional cost. Numerical results are presented to demonstrate the accuracy and efficiency of the method. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

17.
非圆回转曲面CNC 磨削加工轨迹直接插补技术研究   总被引:1,自引:0,他引:1  
 针对非圆回转曲面数控磨削加工轨迹插补特点,动用曲面直接插补(SDI)思想,提出一种适合于非圆回转曲面类零件轨迹处理的集成式CNC轨迹插补模式,并系统研究了实时插补中加工工艺余量智能决策方法和轨迹自生成原理等,成功地解决了非圆回转曲面磨削加工的轨迹实时插补控制问题。  相似文献   

18.
面向数字相机的CCD像素颜色插值新算法研究   总被引:6,自引:2,他引:4  
与立方卷积法和神经网络法相比,线性插值方法具有运算速度快的优点,在数字相机的插值技术中经常采用,为了提高图像质量,提出一种双相关线性插值方法,这种方法根据绿色分量的相关性对红蓝两种分量进行插值,并根据红蓝分量的相关性对绿色分量进行插值,实验表明,这种方法对于增强图像边缘效果较好。  相似文献   

19.
The purpose of this paper is to give a local tricubic interpolation scheme in three dimensions that is both C1 and isotropic. The algorithm is based on a specific 64 × 64 matrix that gives the relationship between the derivatives at the corners of the elements and the coefficients of the tricubic interpolant for this element. In contrast with global interpolation where the interpolated function usually depends on the whole data set, our tricubic local interpolation only uses data in a neighbourhood of an element. We show that the resulting interpolated function and its three first derivatives are continuous if one uses cubic interpolants. The implementation of the interpolator can be downloaded as a static and dynamic library for most platforms. The major difference between this work and current local interpolation schemes is that we do not separate the problem into three one‐dimensional problems. This allows for a much easier and accurate computation of higher derivatives of the extrapolated field. Applications to the computation of Lagrangian coherent structures in ocean data are briefly discussed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

20.
文献[22]中已经构造了一种基于函数值的带参数的二元有理插值样条,它是分子为双四次、分母为双二次的有理样条。论文研究了该种二元有理插值样条的有界性,给出了插值的逼近表达式,讨论了插值曲面形状的点控制问题。在插值条件不变的情况下,插值区域内任一点插值函数的值可以根据设计的需要通过对参数的选取修改,从而达到插值曲面局部修改的目的。  相似文献   

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