共查询到18条相似文献,搜索用时 347 毫秒
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提出一种四边形网格细分算法:每细分一次四边形网格,其数目增加为原来的两倍,细分二次结果相当于一次二分细分,采用边数缓慢增长的策略,使生成的曲面光滑连续。该算法生成曲面在规则点具有C2连续性,在非规则点具有C1连续性。该算法对网格几何操作简单,所得网格数据量增长相对缓慢,适合3D图像重构及网络传输等应用领域。由于文中细分算法对初始网格的拓扑变更,因此第一次细分会产生扭曲现象,但后面的细分会逐步光滑。 相似文献
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四边形网格的去边细分方法 总被引:5,自引:0,他引:5
提出一种四边形网格细分算法:每细分一次四边形网格,其数目增加为原来的两倍,细分二次结果相当于一次二分细分和一个旋转.该算法采用三次B样条张量积的形式,其生成曲面在规则点具有C^2连续性,在非规则点具有C^1连续性.由于该细分算法对网格几何操作简单,所得网格数据量增长相对缓慢,适合于3D图像重构及网络传输等应用领域。 相似文献
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提出一种四边形网格细分算法:每细分一次四边形网格,其数目增加为原来的两倍,细分二次结果相当于一次二分细分,采用边数缓慢增长的策略,使生成的曲面光滑连续.该算法生成曲面在规则点具有C2连续性,在非规则点具有C1连续性.该算法对网格几何操作简单,所得网格数据量增长相对缓慢,适合3D图像重构及网络传输等应用领域.由于文中细分算法对初始网格的拓扑变更,因此第一次细分会产生扭曲现象,但后面的细分会逐步光滑. 相似文献
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在任意拓扑的四边形网格上构造光滑的曲面是计算机辅助几何设计中的一个重要问题.基于C-C细分,提出一种从四边形网格上生成插值网格顶点的光滑Bézier曲面片的算法.将输入四边形网格作为C-C细分的初始控制网格,在四边形网格的每张面上对应得到一张Bézier曲面,使Bézier曲面片逼近C-C细分极限曲面.曲面片在与奇异顶点相连的边界上G1连续,其他地方C2连续.为解决C-C细分的收缩问题,给出了基于误差控制的迭代扩张初始控制网格的方法,使从扩张后网格上生成的曲面插值于初始控制网格的顶点.实验结果表明,该算法效率高,生成的曲面具有较好的连续性,适用于对四边化后的网格模型上重建光滑的曲面. 相似文献
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在任意拓扑的四边形网格上构造光滑的曲面是计算机辅助几何设计中的一个重要问题.基于C—C细分,提出一种从四边形网格上生成插值网格顶点的光滑Bezier曲面片的算法.将输入四边形网格作为C—C细分的初始控制网格,在四边形网格的每张面上对应得到一张Bezier曲面,使Bezier曲面片逼近C—C细分极限曲面.曲面片在与奇异顶点相连的边界上G^1连续,其他地方C^2连续.为解决C—C细分的收缩问题,给出了基于误差控制的迭代扩张初始控制网格的方法,使从扩张后网格上生成的曲面插值于初始控制网格的顶点.实验结果表明,该算法效率高,生成的曲面具有较好的连续性,适用于对四边化后的网格模型上重建光滑的曲面. 相似文献
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全四边形有限元网格的拓扑优化策略 总被引:6,自引:0,他引:6
基于有限元网格的局部拓扑结构,给出一些非结构化全四边形有限元网格的拓扑优化策略,这些策略被组织成"型-操作"的形式.型是指一类满足一定约束条件的局部区域网格,而操作则是指与特定型相对应的拓扑变换,它能优化局部网格中节点的度值,从而优化局部网格质量.这些策略可分成针对网格内部单元和针对网格边界单元2类.实验结果表明,这些策略能较好地改善四边形网格的质量. 相似文献
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已有的四边形网格的简化及优化方法大多数都是三角形网格简化在局部几何上的推广.四边形网格的结构受螺旋条带的影响,移除四边形网格中的螺旋条带则可以在拓扑结构上明显提高四边形网格的质量.文中具体讨论了四边形网格上螺旋条带与网格上奇异点的关系及其性质,并根据这个性质给出了四边形网格中螺旋条带的一般生成算法.实验结果表明,该算法可以有效地搜索四边形网格上的螺旋条带,进而通过删除螺旋条带优化四边形网格的拓扑结构. 相似文献
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This article presents an efficient construction of biorthogonal wavelets built upon an interpolatory subdivision for quadrilateral meshes. The interpolatory subdivision scheme is first turned into a scheme for reversible primitive wavelet synthesis. Some desired properties are then incorporated in the primitive wavelet using the lifting scheme. The analysis and synthesis algorithms of the resulting new wavelet are finally obtained as local and in-place lifting operations. The wavelet inherits the advantage of refinement with added levels of resolution. Numerical experiments show that the lifted wavelet built upon interpolatory subdivision has sufficient stability and better performance in dealing with closed or open semi-regular quadrilateral meshes compared with other existing wavelets for quadrilateral manifold meshes. 相似文献
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Artifact analysis on triangular box-splines and subdivision surfaces defined by triangular polyhedra
Surface artifacts are features in a surface which cannot be avoided by movement of control points. They are present in B-splines, box splines and subdivision surfaces. We showed how the subdivision process can be used as a tool to analyse artifacts in surfaces defined by quadrilateral polyhedra (
[Sabin et al., 2005] and [Augsd?rfer et al., 2011]).In this paper we are utilising the subdivision process to develop a generic expression which can be employed to determine the magnitude of artifacts in surfaces defined by any regular triangular polyhedra. We demonstrate the method by analysing box-splines and regular regions of subdivision surfaces based on triangular meshes: Loop subdivision, Butterfly subdivision and a novel interpolating scheme with two smoothing stages. We compare our results for surfaces defined by triangular polyhedra to those for surfaces defined by quadrilateral polyhedra. 相似文献
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《Computer Aided Geometric Design》2014,31(7-8):475-485
In this paper, we introduce triangular subdivision operators which are composed of a refinement operator and several averaging operators, where the refinement operator splits each triangle uniformly into four congruent triangles and in each averaging operation, every vertex will be replaced by a convex combination of itself and its neighboring vertices. These operators form an infinite class of triangular subdivision schemes including Loop's algorithm with a restricted parameter range and the midpoint schemes for triangular meshes. We analyze the smoothness of the resulting subdivision surfaces at their regular and extraordinary points by generalizing an established technique for analyzing midpoint subdivision on quadrilateral meshes. General triangular midpoint subdivision surfaces are smooth at all regular points and they are also smooth at extraordinary points under certain conditions. We show some general triangular subdivision surfaces and compare them with Loop subdivision surfaces. 相似文献
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提出一种基于形状控制的 Catmull-Clark 细分曲面构造方法,实现局部插值任意拓扑的四边形网格顶点。首先该方法利用渐进迭代逼近方法的局部性质,在初始网格中选取若干控制顶点进行迭代调整,保持其他顶点不变,使得最终生成的极限细分曲面插值于初始网格中的被调整点;其次该方法的 Catmull-Clark 细分的形状控制建立在两步细分的基础上,第一步通过对初始网格应用改造的 Catmull-Clark 细分产生新的网格,第二步对新网格应用 Catmull-Clark 细分生成极限曲面,改造的 Catmull-Clark 细分为每个网格面加入参数值,这些参数值为控制局部插值曲面的形状提供了自由度。证明了基于形状控制的 Catmull-Clark 细分局部渐进插值方法的收敛性。实验结果验证了该方法可同时实现局部插值和形状控制。 相似文献
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Surface modeling with ternary interpolating subdivision 总被引:3,自引:0,他引:3
In this paper, a new interpolatory subdivision scheme, called ternary interpolating subdivision, for quadrilateral meshes with arbitrary topology is presented. It can be used to deal with not only extraordinary faces but also extraordinary vertices in polyhedral meshes of arbitrary topologies. It is shown that the ternary interpolating subdivision can generate a C1-continuous interpolatory surface. Some applications with open boundaries and curves to be interpolated are also discussed. 相似文献
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Ever since its introduction by Stam and Loop, the quad/triangle subdivision scheme, which is a generalization of the well-known
Catmull–Clark subdivision and Loop subdivision, has attracted a great deal of interest due to its flexibility of allowing
both quads and triangles in the same model. In this paper, we present a novel biorthogonal wavelet—constructed through the
lifting scheme—that accommodates the quad/triangle subdivision. The introduced wavelet smoothly unifies the Catmull–Clark
subdivision wavelet (for quadrilateral meshes) and the Loop subdivision wavelet (for triangular meshes) in a single framework.
It can be used to flexibly and efficiently process any complicated semi-regular hybrid meshes containing both quadrilateral
and triangular regions. Because the analysis and synthesis algorithms of the wavelet are composed of only local lifting operations
allowing fully in-place calculations, they can be performed in linear time. The experiments demonstrate sufficient stability
and fine fitting quality of the presented wavelet, which are similar to those of the Catmull–Clark subdivision wavelet and
the Loop subdivision wavelet. The wavelet analysis can be used in various applications, such as shape approximation, progressive
transmission, data compression and multiresolution edit of complex models.
相似文献
Kai Tang (Corresponding author)Email: |
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REN Shui-li ZHANG Kai-yuan YE Zheng-lin 《通讯和计算机》2007,4(5):57-61
Based on triangle and quadrilateral meshes, this paper presents an adjustable subdivision surface scheme. The scheme can produce subdivision surface of Cl continuity of limit surface Since an adjustable parameter is introduced to the scheme, the surface modeling is flexible. Depended on given initial data, the limited surface shape can be adjusted and controlled through selecting appropriate parameters. The method is effective in generating smooth surfaces. 相似文献
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提出了一种基于四边形网格的可调细分曲面造型方法。该方法不仅适合闭域拓扑结构,且对初始网格是开域的也能进行处理。细分算法中引入了可调参数,增加了曲面造型的灵活性。在给定初始数据的条件下,曲面造型时可以通过调节参数来控制极限曲面的形状。该方法可以生成C1连续的细分曲面。试验表明该方法生成光滑曲面是有效的。 相似文献