共查询到18条相似文献,搜索用时 85 毫秒
1.
体积平方度量下的特征保持网格简化方法 总被引:5,自引:0,他引:5
提出了一种基于体积平方度量的三角形折叠网格简化新方法.新方法通过极小化误差目标函数简化三角形网格.简化误差定义为三角形简化后产生的网格模型平方体积变化,并以三角形几何形状因子和法向因子作为约束.简化误差的表示形式为一个二次目标函数,因此,每次简化后三角形网格的新顶点是一个线性问题的解.与目前简化效率最好的QEM方法相比,新方法不增加算法复杂度.如果被简化的三角形是强特征三角形,则用其高斯曲率最大的顶点作为新顶点,以保持原始模型的细节特征;对于非强特征三角形,新顶点用极小化折叠误差确定.对于边界三角形,新顶点的位置由不同于内部三角形的方法进行计算,保持了网格的边界特征.最后用实例说明新方法的有效性. 相似文献
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在边折叠简化方法的基础上,提出一种用体积变化的平方作为误差度量的三角网格简化算法。算法中引入三角形法向约束因子的概念,并把它嵌入到边折叠误差矩阵中;能够自适应地分配简化网格的疏密,保持更多的模型几何特征。实验表明,该算法简化误差低,模型视觉质量高,简化效果较好。 相似文献
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目前提出的网格简化算法中,三角形折叠简化方法是一种主要的简化方法,在网格压缩、多细节层次模型生成、递进网格构造中得到了广泛地应用。提出一种基于三角形折叠的网格模型简化改进算法,在基于三角形折叠的基础上,在计算三角形折叠误差代价时引入局部区域面积度量参数,有效控制简化模型的三角形折叠顺序。实验表明,采用该文算法简化后的模型更逼近原始模型。 相似文献
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提出了一种基于控制点误差控制的网格简化算法,以初始网格三角形的中心点作为第一类控制点,以特征边的顶点作为第二类控制点,控制点与受控三角形之间的距离作为简化误差。根据设定的三角形权重,按照顺序进行三角形折叠操作,简化操作后必须满足控制点到受控三角形的距离小于阈值。 相似文献
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一种改进的基于三角形折叠的网格简化算法 总被引:4,自引:1,他引:4
在已有的基于三角形折叠网格简化算法的基础之上,提出了一种改进的算法。对原算法的误差矩阵的计算进行了改进,提出了一种简单的误差控制方法。该改进的简化算法不仅能减少模型中的三角形数目和保持模型拓扑结构,而且实现简单、速度快。 相似文献
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针对模型简化过程中出现的特征细节丢失、简化结果过于均匀等问题,文中基于特征保持提出一种改进的三角形折叠网格简化算法。简化前对原始模型中的三角形预分类,简化中以二次误差测度度量简化过程,以三角形狭长度、局部区域面积以及局部区域尖锐度控制三角形简化顺序,对边界三角形和内部三角形采取不同的简化策略,以此保持模型特征和降低算法复杂度。本算法在Visual c++6.0开发环境下,结合OpenGL编程语言实现。实验结果表明,改进算法采用延迟简化特征区域及形状好的三角形的方法,有效地保持了模型原始特征,且简化速度较快。 相似文献
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基于子分规则的边折叠简化方法 总被引:15,自引:0,他引:15
边折叠简化方法是一种主要的三角网格简化方法,已成为多分辨率自适应曲面参数化,基于法向细节的几何压缩,渐进风格算法的重要组成部分,文中采用子分的思想生成三角网格模型的新顶点,从而减小了简化模型和原始模型之间的误差,此外,还给出保持模型流形的方法,最后给出一种新的计算简化网络与原发中网络之间的Metro距离的采样方法,并分析这个距离误差。 相似文献
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Constructing hierarchies for triangle meshes 总被引:5,自引:0,他引:5
Gieng T.S. Hamann B. Joy K.I. Schussman G.L. Trotts I.J. 《IEEE transactions on visualization and computer graphics》1998,4(2):145-161
We present a method to produce a hierarchy of triangle meshes that can be used to blend different levels of detail in a smooth fashion. The algorithm produces a sequence of meshes M0, M1, M 2..., Mn, where each mesh Mi can be transformed to mesh Mi+1 through a set of triangle-collapse operations. For each triangle, a function is generated that approximates the underlying surface in the area of the triangle, and this function serves as a basis for assigning a weight to the triangle in the ordering operation and for supplying the points to which the triangles are collapsed. The algorithm produces a limited number of intermediate meshes by selecting, at each step, a number of triangles that can be collapsed simultaneously. This technique allows us to view a triangulated surface model at varying levels of detail while insuring that the simplified mesh approximates the original surface well 相似文献
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Level Of Detail (LOD) modelling or mesh reduction has been found useful in interactive walkthrough applications. Progressive meshing techniques based on edge or triangle collapsing have been recognised useful in continuous LOD, progressive refinement, and progressive transmission. We present a vertex-collapsing mesh reduction scheme that effectively takes shape and feature preserving as well as material-discontinuity preserving into account, and produces a progressive mesh which generally has more vertices collapsed between adjacent levels of detail than methods based on edge-collapsing and triangle collapsing. 相似文献
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提出在三角网格中利用多个三角形组合及检索n边形(n为正整数)的规则,并提出一种具有相似折叠规律的n边形折叠的网格简化算法,该算法以n边形折叠为基本简化操作,并以二次误差作为误差度量,每次n边形折叠操作可以减少n-1个顶点以及2(n-1)个三角形,n越大达到某一简化目标所需的折叠次数越少,因此简化速度也可能越快.通过选取适当的n值及新顶点位置,新算法可以转化成顶点删除、边折叠及三角形折叠3种已知的几何元素删除算法,因此也可以视做为基于二次误差度量的几何元素删除简化算法的总括算法.最后分别对几种n取值情况列举实验数据,说明该算法的有效性. 相似文献
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In this paper, we present an efficient (topology preserving) multiresolution meshing framework for interactive level-of-detail (LOD) generation and rendering of large triangle meshes. More specifically, the presented approach, called FastMesh, provides view-dependent LOD generation and real-time mesh simplification that minimizes visual artifacts. Multiresolution triangle mesh representations are an important tool for reducing triangle mesh complexity in interactive rendering environments. Ideally, for interactive visualization, a triangle mesh is simplified to the maximal tolerated visible error and, thus, mesh simplification is view-dependent. This paper introduces an efficient hierarchical multiresolution triangulation framework based on a half-edge triangle mesh data structure and presents optimized implementations of several view-dependent or visual mesh simplification heuristics within that framework. Despite being optimized for performance, these error heuristics provide conservative error bounds. The presented framework is highly efficient both in space and time cost and needs only a fraction of the time required for rendering to perform the error calculations and dynamic mesh updates. 相似文献
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Adaptive remeshing process with quadrangular finite elements 总被引:2,自引:0,他引:2
Akira Tezuka 《Advances in Engineering Software》1992,15(3-4):185-201
Since the quality of FEM analysis directly depends on the quality of meshes, various mesh adaptation schemes have been researched. There are two stages on adaptive finite element analysis; to derive error measure and to control meshes based on error measure. The former has been well researched among applied mathematicians. However, the importance of the latter aspect wasn't considered enough. Even if the error measures were well estimated, the total performance of mesh adaptation might be poor with a poor mesh control. This paper proposes an effective mesh control scheme for h-adaptation, or adaptive remeshing scheme with the explicit relation between interpolation theory based on error measure and desirable mesh size. Total mesh adaptation is controlled by introducing Quality Index, or the ratio between the total error norm and the total energy norm which represents the quality of the total meshes; specifying the desirable value of Quality Index, then the adaptive remeshing process can handle it and Quality Index is almost converged to the given value. Since the full automatic feature of the mesh generator is a prerequisite for adaptive remeshing, the author also discusses the algorithm of the quadrangular mesh generator for arbitrary domains. After evaluation on a linear problem, it's confirmed that the proposed mesh control scheme and the proposed error measure-mesh size relations are acceptable. The incompatible case for mesh adaptation is also discussed in this paper. 相似文献
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基于自组织特征映射神经网络构建的三角形网格模型可以实现测量点云
压缩后的Delaunay 三角逼近剖分,但该模型存在逼近误差和边缘误差。为减小三角形网格
的逼近误差和边缘误差,构建了精确逼近的三角形网格模型。首先采用整个测量点云,对三
角形网格模型中的所有神经元进行整体训练;然后对三角形网格中的网格神经元的位置权
重,沿网格顶点法矢方向进行修正;最后采用测量点云中的边界点集,对三角形网格模型中
的网格边界神经元进行训练。算例表明,应用该模型,可以有效减小三角形网格的边缘误差,
三角形网格逼近散乱点云的逼近精度得到大幅提高并覆盖散乱点云整体分布范围。 相似文献
18.
Andrea Tagliasacchi Ibraheem Alhashim Matt Olson Hao Zhang 《Computer Graphics Forum》2012,31(5):1735-1744
Inspired by recent developments in contraction‐based curve skeleton extraction, we formulate the skeletonization problem via mean curvature flow (MCF). While the classical application of MCF is surface fairing, we take advantage of its area‐minimizing characteristic to drive the curvature flow towards the extreme so as to collapse the input mesh geometry and obtain a skeletal structure. By analyzing the differential characteristics of the flow, we reveal that MCF locally increases shape anisotropy. This justifies the use of curvature motion for skeleton computation, and leads to the generation of what we call “mean curvature skeletons”. To obtain a stable and efficient discretization, we regularize the surface mesh by performing local remeshing via edge splits and collapses. Simplifying mesh connectivity throughout the motion leads to more efficient computation and avoids numerical instability arising from degeneracies in the triangulation. In addition, the detection of collapsed geometry is facilitated by working with simplified mesh connectivity and monitoring potential non‐manifold edge collapses. With topology simplified throughout the flow, minimal post‐processing is required to convert the collapsed geometry to a curve. Formulating skeletonization via MCF allows us to incorporate external energy terms easily, resulting in a constrained flow. We define one such energy term using the Voronoi medial skeleton and obtain a medially centred curve skeleton. We call the intermediate results of our skeletonization motion meso‐skeletons; these consist of a mixture of curves and surface sheets as appropriate to the local 3D geometry they capture. 相似文献