共查询到20条相似文献,搜索用时 338 毫秒
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提出了一种基于维纳插值模型的帧内错误隐藏插值算法WIEC。算法采用最近的相邻点作为插值的参考点,同时对传统插值选点方法进行改进,将已恢复的像素点用作估值,使得算法可以较好的恢复图像中如边缘特征等一些重要信息。考虑到误差积累和计算复杂度等问题,又提出了一种螺旋型插值顺序模式。该插值顺序模式不仅提高了插值精度,而且减小了最大插值误差。仿真实验表明,算法具有良好的错误隐藏效果。 相似文献
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型值点的个数与分布对B样条曲线的形状有直接影响,为了让B样条曲线能很好地描述图像区域边缘,研究了一种自适应3次非均匀B样条曲线插值算法。利用B样条曲线在型值点处曲率较大的性质,调整型值点的位置和个数,通过B样条曲线与图像边缘的误差,对型值点进一步优化,使B样条曲线贴合边缘。实验结果表明,该方法得到的B样条曲线能很好地描述区域边缘。 相似文献
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带端点插植条件的Bezier曲线降多阶逼近 总被引:20,自引:2,他引:18
研究了两端点具有任意阶插值条件的Bezier曲线降多阶逼近的问题。对于给定的首末端点的各阶插值条件,给出了一种新的一次降多阶逼近算法,应用Chebyshev多项式逼近理论达到了满足端点插值条件下的近似最佳一致逼近,此算法易于实现,误差计算简单,且所得降价曲线具有很好的逼近效果,结合分割算法,可获得相当高的误差收剑速度。 相似文献
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根据微分几何理论,给出一种可展曲面上G2连续的曲线插值算法.构造一等距对应将可展曲面展成平面,从而将原问题转化为通常的平面上的曲线插值问题.在R2上利用二次三角B样条曲线插值型值点列,无需反算控制顶点,证明了所得的可展曲面上的插值曲线是G2连续的.理论推导和实例均表明,该算法具有推广应用的广阔前景. 相似文献
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为了得到平滑的人体动画,提出一种基于四元数的样条插值算法,利用提取的关键帧实现人体运动序列的有效重构。为减少重构误差、加快收敛速度,将已知关键帧集合作为初始条件,通过迭代算法求出样条曲线的控制点集合。利用样条曲线控制点计算贝塞尔曲线控制点,构造贝塞尔样条曲线段,将各段贝塞尔样条曲线段组合,构造一条基于四元数的样条曲线。根据德卡斯特里奥(de Casteljau)算法插值重构人体运动。实验结果表明,该算法在保证执行效率的同时,可得到光滑的插值结果,实现满足视觉要求的人体运动重构。 相似文献
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带端点插值条件的Bézier曲线降多阶逼近 总被引:8,自引:0,他引:8
研究了两端点具有任意阶插值条件的Bézier曲线降多阶逼近的问题.对于给定的首末端点的各阶插值条件,给出了一种新的一次降多阶逼近算法,应用Chebyshev多项式逼近理论达到了满足端点插值条件下的近似最佳一致逼近.此算法易于实现,误差计算简单,且所得降阶曲线具有很好的逼近效果,结合分割算法,可获得相当高的误差收敛速度. 相似文献
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A new approach for cubic B-spline curve approximation is presented. The method produces an approximation cubic B-spline curve tangent to a given curve at a set of selected positions, called tangent points, in a piecewise manner starting from a seed segment. A heuristic method is provided to select the tangent points. The first segment of the approximation cubic B-spline curve can be obtained using an inner point interpolation method, least-squares method or geometric Hermite method as a seed segment. The approximation curve is further extended to other tangent points one by one by curve unclamping. New tangent points can also be added, if necessary, by using the concept of the minimum shape deformation angle of an inner point for better approximation. Numerical examples show that the new method is effective in approximating a given curve and is efficient in computation. 相似文献
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Qin Kaihuai 《计算机科学技术学报》1997,12(1):76-89
New algorithms based on artificial neural network models are presented for cubic NURBS curve and surface interpolation.When all th knot spans are identical,the NURBS curve interpolation procedure degenerates into that of uniform rational B-spline curves.If all the weights of data points are identical,then the NURBS curve interpolation procedure degenerates into the integral B-spline curve interpolation. 相似文献
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Shu-ichi Gofuku Author VitaeAuthor Vitae Takashi Maekawa Author Vitae 《Computer aided design》2009,41(6):412-422
We introduce a novel method to interpolate a set of data points as well as unit tangent vectors or unit normal vectors at the data points by means of a B-spline curve interpolation technique using geometric algorithms. The advantages of our algorithm are that it has a compact representation, it does not require the magnitudes of the tangent vectors or normal vectors, and it has C2 continuity. We compare our method with the conventional curve interpolation methods, namely, the standard point interpolation method, the method introduced by Piegl and Tiller, which interpolates points as well as the first derivatives at every point, and the piecewise cubic Hermite interpolation method. Examples are provided to demonstrate the effectiveness of the proposed algorithms. 相似文献
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论文提出了一种带光滑有序点列约束的B 样条曲线延伸方法。该算法能
够根据约束点列的情况对曲线延伸部分所对应的节点值进行优化,通过插值尽量少的约束
点,使得延伸曲线与约束点列之间的最大距离小于预先给定的误差值,并且延伸曲线与原始
曲线之间自然达到最大阶连续。该方法也同样适用于带曲线约束的B 样条曲面延伸。实例
表明,所提出的算法是可行且有效的。 相似文献
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为了用一种模型实现从逼近到插值的转换,在多项式空间上构造了含一个参数的调配函数,由之定义了基于4点分段的曲线,该曲线可以理解为由相同的一组控制顶点定义的逼近曲线和插值曲线的线性组合,其中的逼近曲线为3次均匀B样条曲线,插值曲线经过除首末点以外的所有控制点。在均匀参数分割下,曲线具有C2连续性,取特殊参数时可达C3连续。在参数变化过程中,曲线各段起点、终点的位置发生改变,但这些点处的一阶、二阶导矢始终保持不变,即始终与3次B样条曲线相同。曲线形状与端点条件密切相关,而B样条曲线具有良好的保形性,这些综合因素使得曲线在形状变化的过程中始终可以较好地保持控制多边形的特征。采用张量积方法将曲线推广至曲面,曲线曲面图例显示了该方法在造型设计中的有效性。 相似文献
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目的 为了同时解决传统多项式B样条曲线在形状调控、精确表示常见工程曲线以及构造插值曲线时的不足,提出了一类集多种特性的三次三角伪B样条。方法 首先构造了一组带两个参数的三次三角伪B样条基函数,然后在此基础上定义了相应的参数伪B样条曲线,并讨论了该曲线的特性及光顺性问题,最后研究了相应的代数伪B样条,并给出了最优代数伪B样条的确定方法。结果 参数伪B样条曲线不仅满足C2连续,而且无需求解方程系统即可自动插值于给定的型值点。当型值点保持不变时,插值曲线的形状还可通过自带的两个参数进行调控。在适当条件下,该参数伪B样条曲线可精确表示圆弧、椭圆弧、星形线等常见的工程曲线。相应的代数伪B样条具有参数伪B样条曲线类似的性质,利用最优代数伪B样条可获得满意的插值效果。结论 所提出的伪B样条同时解决了传统多项式B样条曲线在形状调控、精确表示常见工程曲线以及构造插值曲线时的不足,是一种实用的曲线造型方法。 相似文献
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Syh-Shiuh YehAuthor VitaePau-Lo HsuAuthor Vitae 《Computer aided design》2002,34(3):229-237
Recently, modern manufacturing systems have been designed which can machine arbitrary parametric curves while greatly reducing data communication between CAD/CAM and CNC systems. However, a constant feedrate and chord accuracy between two interpolated points along parametric curves are generally difficult to achieve due to the non-uniform map between curves and parameters. A speed-controlled interpolation algorithm with an adaptive feedrate is proposed in this paper. Since the chord error in interpolation depends on the curve speed and the radius of curvature, the feedrate in the proposed algorithm is automatically adjusted so that a specified limit on the chord error is met. Both simulation and experimental results for non-uniform rational B-spline (NURBS) examples are provided to verify the feasibility and precision of the proposed interpolation algorithm. 相似文献
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Yu-Hua Gu Tjahjadi T. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》1999,29(4):358-367
In this paper, we consider the problem of matching 2D planar object curves from a database, and tracking moving object curves through an image sequence. The first part of the paper describes a curve data compression method using B-spline curve approximation. We present a new constrained active B-spline curve model based on the minimum mean square error (MMSE) criterion, and an iterative algorithm for selecting the “best” segment border points for each B-spline curve. The second part of the paper describes a method for simultaneous object tracking and affine parameter estimation using the approximate curves and profiles. We propose a novel B-spline point assignment algorithm which incorporates the significant corners for interpolating corresponding points on the two curves to be compared. A gradient-based algorithm is presented for simultaneously tracking object curves, and estimating the associated translation, rotation and scaling parameters. The performance of each proposed method is evaluated using still images and image sequences containing simple objects 相似文献