共查询到18条相似文献,搜索用时 109 毫秒
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一种基于能量法的自由曲面展开算法 总被引:4,自引:0,他引:4
提出了一种基于能量法的自由曲面展开算法,适用于任意复杂自由曲面的展开.根据建立的曲面能量模型,采用映射法进行曲面的Delaunay三角网格划分,并计算空间网格三角形点的变形能,然后进行变形能的释放,得到自由曲面展开后的二维平面.能量法不拘于问题的形式,可以用来求解一般的问题,该算法具有一定的通用性,适用于CAD/CAM中的曲面展开问题. 相似文献
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针对复杂网格曲面分型线提取精度和效率不高的问题,根据非封闭自由曲面和封闭自由曲面的拓扑信息和几何特点,提出了2种基于投影方法的分型线提取算法. 对非封闭模型,首先将模型投影到平面并重新三角网格化,然后提取投影三角网格的边界,最后以平面三角网格的边界为检索信息在原始网格中检索得到自由曲面的分型线. 对封闭模型,根据模具分模的几何原理,提出通过建立封闭自由曲面凹模和凸模离散几何模型的方法提取封闭自由曲面的分型点,然后通过一环邻域点搜索法对分型点排序,得到分型线. 实验结果和数据分析表明,两种方法可以精确、高效地提取非封闭和封闭自由曲面的分型线,并可以确保分型点都是三角网格曲面的顶点. 相似文献
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基于单元等变形的复杂曲面展开算法研究 总被引:3,自引:0,他引:3
针对板壳类零件展开问题提出了一种基于单元等变形的复杂曲面展开算法。首先利用有限元网格生成算法将零件曲面划分成三角形单元 ,然后按照单元等变形假设将三角形单元映射到平面上 ,从而得到曲面的展开形状与尺寸 ,并通过重新计算单元的变形率得到曲面内的应变分布。该算法可以将各种可展曲面和不可展曲面采用统一的形式展开 ,实际应用表明采用该算法展开复杂曲面时具有快速准确的特点 ,可以显著缩短零件从设计造型到求取其毛料外形的时间 ,适用于航空航天及汽车制造等工业领域内具有复杂曲面的金属板料零件的数字化展开。 相似文献
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针对复杂三维网格曲面的展开,提出了一种基于翼边数据结构的区域划分方案。对单边界、双边界、多边界曲面以及封闭曲面,建立相应的翼边数据结构,根据离散高斯曲率生成剪口路径,并更新数据结构;对于复杂的曲面数据模型,则首先进行区域分块,把三维实体分为若干个相对简单的小区域,再根据需要决定是否对分块后的模型继续进行剪口。最后采用相关展开算法对区域划分的结果进行了展开。 相似文献
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针对两匹配模型之间的相对初始位置相差太大而使ICP算法收敛方向不确定的问题,提出一种基于能量法的曲面初始配准技术,即首先要根据两个曲面的质心及质心处的法向矢量对曲面进行初始变换,使它们的质心重合并且法矢方向一致,然后将一曲面以质心法矢为旋转轴进行坐标变换,能量差最小的位置即为最优配准位置。经验证,该配准算法运算速度快、效率高,能较好地应用于曲面类零件测量数据与目标数据的初始配准问题。 相似文献
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针对三角网格模型,提出了一种基于隐式曲面的等距算法.该算法首先对三角网格模型进行拓扑重建,然后对顶点进行八叉树采样,由采样点及采样点的单位法矢点来构建隐式曲面,将隐式曲面等距,最后将原模型的顶点投影到等距曲面得到投影点,根据先前建立的拓扑关系,将投影点三角网格化得到等距后的三角网格模型.该算法在一定数值范围内避免了等距模型自交问题,而且等距模型三角网格均匀,质量高. 相似文献
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为提高快速成型制造中STL模型切片轮廓的光滑性,提出了一种基于Loop模式的自适应曲面细分算法,首先分割出网格模型中的曲面和平面,对和尖锐边相邻的曲面三角面设计了特殊的细分规则.通过三角面顶点的平坦度和容差平坦度决定三角面是否做进一步细分,以达到自适应细分的目的.该算法在保留零件模型上尖锐特征的同时,提高了模型上曲面部分的光顺性,从而可以利用模型的全局信息获得光滑的2维切片数据. 相似文献
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Flattening triangulated surfaces using a mass-spring model 总被引:9,自引:0,他引:9
Jituo Li Dongliang Zhang Guodong Lu Yanying Peng Xing Wen Yoshiyuki Sakaguti 《The International Journal of Advanced Manufacturing Technology》2005,25(1-2):108-117
Flattening 3D surfaces is a challenging problem in the product design community. This paper presents an efficient flattening algorithm using a mass-spring model. In the mass spring model, crossed-springs are introduced to reduce the distortion of the resulting surface. The process of planar development is made faster by using triangle strips. To solve the problem of overlapping, the paper proposes a constrained flattening iteration method and a local correction method. Experimental results show that the algorithm can deal with complex surfaces efficiently. 相似文献
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Weiwen Liang Hongzan Bin 《The International Journal of Advanced Manufacturing Technology》2004,24(11-12):853-859
Flattening of freeform surfaces (i.e., non-developable surfaces) is a difficult problem in engineering application. According to flattening distortions, a new development based on energy model is put forward in this paper. Given a doubly curved surface and using a triangle mesh subdivision, some triangles will be distorted when the surface is flattened. Generally, the developed plane will possess many splits. There are two kinds of developments: unconstrained flattening and constrained flattening, which are both analysed. In order to obtain a better pattern, the strain energy required to force a 3-D shape adopt the plane pattern should be minimised. At last a flattening algorithm is developed on the basis of theoretical analyses. Compared with the others, the proposed method can control the local precision easily, and is an effective method for flattening doubly curved surfaces. 相似文献
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In this study, a complete 3D surface reconstruction method is proposed based on the concept that the vertices of surface model
can be completely matched to the unstructured point cloud. In order to generate the initial mesh model from the point cloud,
the mesh subdivision of bounding box and shrink-wrapping algorithm are introduced. The control mesh model for well representing
the topology of point cloud is derived from the initial mesh model by using the mesh simplification technique based on the
original QEM algorithm, and the parametric surface model for approximately representing the geometry of point cloud is derived
by applying the local subdivision surface fitting scheme on the control mesh model. And, to reconstruct the complete matching
surface model, the insertion of isolated points on the parametric surface model and the mesh optimization are carried out.
Especially, the fast 3D surface reconstruction is realized by introducing the voxel-based nearest-point search algorithm,
and the simulation results reveal the availability of the proposed surface reconstruction method. 相似文献
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复杂三维形体的多细节层次描述在产品概念设计、虚拟现实、网络协同交互等方面都有着广泛的应用前景。现有方法主要采用纯图形技术实现。本文通过全景深度图像描述复杂三维形体 ,通过建立在其上的初始三角形网格的自动细化 ,来实现复杂三维形体的多细节层次描述。本方法算法简单 ,自动化程度高 ,适合于一大类复杂三维形体的描述。 相似文献
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在分析逆向工程系统模型的基础上,提出一种基于局部曲面重建的逆向工程系统模型,可以根据现有产品的测量数据直接显示三维图像和快速成型,大大缩短逆向工程所需的时间,免除了大量复杂曲面建模的困难,同时分析了基于光线追踪的体绘制算法的原理和影响显示效率的因素,设计了光线追踪显示体数据的新求交算法。实验结果表明,该算法具有较强的实用价值,对于进一步推动逆向工程的研究和实用化具有重要的意义。 相似文献
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三维表面测量中的高斯滤波快速算法 总被引:2,自引:0,他引:2
基于中心极限定理提出了一个高斯滤波器逼近模型,并利用冲激响应不变法设计了数字高斯滤波器.通过级联方法,该滤波器的幅度传输特性偏差可控制在(-0.28%~+1.14%)以内,扩展为二维高斯滤波器,其三维幅度传输特性偏差可控制在(-0.42%~+1.12%)以内.该滤波器采用递归实现算法,算法简便,易于实现.在递归算法的基... 相似文献
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W. Hu W. Yang Y. Xiong 《The International Journal of Advanced Manufacturing Technology》2005,26(11-12):1362-1369
Reconstructing exact topology mesh from data points is one of the most important tasks in the fields of industrial CAD/CAE/CAM, computational vision and reverse engineering. In this paper, a deflation algorithm that integrates an adaptive mesh and physical constraint model is presented for the 3D reconstruction of geometric-closed shape (genus 0) from unorganized data points. First, an initial mesh is formed using the Delaunay algorithm. Second, an asymptotic deforming performance is accomplished to deflate initial mesh towards the local concave boundary step-by-step. In this phase, a physical constraint model of coupled particle systems based on particle dynamics and Newtonian law of motion is constructed, and the model dynamically controls mesh deformation as a behavior constraint. To guarantee that the resultant mesh is homeomorphous to the original surface of data points, a continuously deforming mechanism, visibility cone and collision-detecting criterions are designed. At last, experimental results in reverse engineering which supports the usefulness of this method for reconstruction . 相似文献