共查询到20条相似文献,搜索用时 140 毫秒
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针对密集点云的三角网格曲面重建,提出一种用于数据精简和分块的神经网络算法:将模糊聚类方法与Kohonen神经网络算法结合.该算法具有按不同曲率进行曲面点云分块重建的能力,而且提高了自组织神经网络的效率.并应用该算法进行了仿真试验,建立了三角拓扑网格曲面,验证了算法的有效性. 相似文献
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Free-form surfaces have been widely used in aerospace, automotive and other fields. Due to its complex geometry, free-form surface inspection is generally conducted by touch-trigger or measuring probe-based Coordinate Measurement Machines or On-machine Measurement. Sampling strategy plays a decisive role in improving both measurement accuracy and efficiency, which is determined by sample size and distribution of sample points. However, it is difficult to simultaneously take the surface curvature, sampling density and approximation error into account, considering the complexity of surface geometry. In this paper, triangle mesh simplification is innovatively adopted in sampling planning to achieve multi-geometric constraints. As triangle mesh has outstanding advantages in representing the surface features, strong stability and is easy to modify its structure, free-form surface is converted to a dense triangle mesh. Triangle mesh simplification is implemented by iteratively contracting triangle edges. An improved quadric error metric is established to decide contraction order and optimal target vertices under discrete curvature constraint. Sampling density is controlled by limiting the triangle edge length. Detailed adaptive sampling algorithm under multi-geometric constraints is then developed. Both simulation and experiment are conducted to validate feasibility and robustness of the proposed method. The results are compared with uniform sampling and existing adaptive sampling strategy to show that the proposed method can prominently reduce sampling error when sample size is small. 相似文献
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基于二维Delaunay近邻的空间散乱数据曲面重建算法 总被引:8,自引:0,他引:8
给出了一种新的散乱数据曲面重建算法。算法基于曲面的局平特性,通过二维Delaunay三角剖分到三维空间的映射,快速查找空间任意点的Delaunay近邻,然后根据散乱数据重建三角网格中顶点互为Delaunay近邻的原理,进行曲面拓扑重建。应用新的求解κ-近邻和二维Delaunay近邻的算法,提高了曲面重建的算法效率。实验表明,该算法高效、稳定,对不均匀数据有较好的适用性。 相似文献
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WU Shixiong WANG Chengyong School of Mechanical Electrical Engineering Guangdong University of Technology Guangzhou China CHEN Zichen College of Mechanical Energy Engineering Zhejiang University Hangzhou China 《机械工程学报(英文版)》2006,(1)
A region-growing method for reconstructing triangulated surfaces from massive unorganized points is presented. To save memory space, a ring data-structure is adopted to build connections between points and triangulated surfaces. The data-structure allows the efficient retrieval of all neighboring vertices and triangles of a given vertice. To narrow the search range of adjacent points and avoid mangle intersection, an influence area is defined for each active-edge. In the region-growing process of triangulated surfaces, a minimum-edge-angle-product algorithm is put forward to select an appropriate point to form a new triangle for an active edge. Results indicate that the presented method has high efficiency and needs less memory space, optimized triangulated surfaces with reliable topological quality can be obtained after triangulation. 相似文献
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高效率的三角网格模型保特征简化方法 总被引:1,自引:0,他引:1
部分三角网格模型因数据量庞大而导致其不便于存储、分析和显示,本文提出了一种结合网格精细化方法的三角形折叠网格简化算法以解决此问题。首先通过3~(1/2)网格细分法确定待折叠三角形三个顶点的修正坐标,并根据修正坐标初步确定折叠点位置,然后引入折叠点的拉普拉斯坐标和原三角形法向信息来更新折叠点位置,最后由三角形折叠后该区域的体积误差和被折叠三角形的平展度共同确定折叠代价,从而使网格优先从较为平坦和特征点较少的区域开始依次进行三角形折叠简化。对多个模型进行了实验测试和数据分析,结果表明该方法能够有效精简网格数据,与3个不同类型的简化方法相比,该方法的简化效率最高,而且能有效保持原网格模型的几何特征并控制简化三角形的质量。 相似文献
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C. C. L. Wang M. M. F. Yuen 《The International Journal of Advanced Manufacturing Technology》2001,18(10):739-744
The method presented in this paper optimises a given triangular mesh surface with respect to prescribed criteria to obtain
a unit surface mesh. Two criteria are defined to guide the mesh optimisation scheme. In the procedure, we use three optimis-ation
operators (edge split, edge collapse, and edge swap), and a local spherical surface is defined to interpolate the given mesh
surface. As a generic algorithm for mesh surface optimisation, our algorithm needs neither parametric surface nor a cloud
of points as references during mesh surface optimisation. 相似文献
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在分析四边拓扑曲面延伸方法的基础上,根据组合三角曲面的特点,提出了组合三角曲面的延伸方向、延伸步距及延伸点的计算方法,由延伸点和原始边界点形成延伸曲面的三角网格,通过分析延伸曲面三角网格的空间关系,提出了延伸曲面的折皱、重叠等奇异情况的分析和处理方法,应用三角形的形状因子,对延伸曲面三角网格中的狭长三角形进行判定,通过延伸点的插入和归并,对三角形网格进行优化处理,以保证延伸曲面的三角网格的品质。最后对原始曲面和延伸曲面的三角网格进行整体G1插值构造,得到延伸后的组合三角曲面模型。应用结果表明,提出的方法可行,算法有效、快速。 相似文献
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提出了一种新的基于子域分解的混合网格生成方法。该方法首先用映射法生成结构化背景网格,并确定实体表面上包含的小孔、键槽等小特征在背景网格中的位置,然后删除这些小特征覆盖的背景网格,并在这些区域内生成三角形网格,最后将剩余的背景网格和生成的三角形网格合并,得到整个目标域的网格。该算法综合了映射法效率高、网格质量好、四边形网格计算精度高,以及三角形网格几何适应能力强的优势。数值实验表明,针对复杂的实体表面,新方法能够全自动地生成质量较好的混合网格,生成的网格质量及算法效率均优于传统的推进波前法和铺砖法。 相似文献
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基于拓扑关系的交线快速生成方法 总被引:1,自引:0,他引:1
三角网格是逆向工程中常用的数据模型。由于模型拓扑关系的复杂性,目前在网格模型的交线生成过程中数据点排序与分离存在诸多缺陷。提出了一种利用网格模型拓扑关系的交线生成与分离算法,该算法充分利用了网格模型的拓扑关系,对各种拓扑类型的数据点完成排序、分离,实现任意复杂拓扑关系的交线生成,为逆向工程中曲线框架的构造提供了依据。 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
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提出了一种基于四叉树法和波前法的有限元网格生成算法。该算法首先将裁剪曲线边界离散成多边形,然后使用四叉树法对待划分裁剪参数曲面按细分要求进行递归分解,最终生成规则的栅格点,最后利用波前法的原理生成三角形网格,通过合并处理生成三角形与四边形混合网格。 相似文献
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为了提高三角网格曲面五轴加工的加工效率,提出了基于最大材料去除率(maximal materialremoval rate,MMR)的平底刀五轴加工刀轨生成算法。首先计算无曲率干涉且具有最大材料去除率的网格曲面五轴加工的刀具方位角;然后在确定网格曲面可能干涉区域的基础上,提出刀触点处干涉性假设,并以最大材料去除率、刀具无曲率干涉和全局干涉为约束条件,采用二分法确定具有最大材料去除率的无干涉刀具方位角;最后采用截面线法生成三角网格曲面MMR平底刀五轴加工刀轨。通过实验验证了采用文中算法生成的刀轨进行加工能够获得较高的加工效率和表面质量。 相似文献
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三维封闭三角网格模型的缺失实体孔洞修复算法 总被引:1,自引:0,他引:1
提出一种针对三维封闭三角网格模型的缺失实体孔洞修复算法,由初始导引点出发,根据几何特征搜索孔洞边界,并以水平集方法扩展边界,获取目标问题区域。基于边界采样和投影方法建立代理曲面,实现了内环三角化细分和三维网格表面的自由变形。通过合并环间区域和引入边缘约束的平滑过程,得到缺失实体孔洞的上缝合面。在此基础上向内扩展,获取孔洞下表面边界轮廓,搜索出上下边界环之间的三角网格区域,并利用同样的方法构建缺失实体孔洞的下缝合面。最终,连接上下缝合面以及两个边界轮廓环之间的三角网格区域得到修复实体。试验制作的样件表明,算法能简化人工交互设计的步骤,生成高质量的修补结果。 相似文献
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提出了一种基于四叉树法和波前法的有限元网格生成算法。该算法首先将裁剪曲线边界离散成多边形,然后使用四叉树法对待划分裁剪参数曲面按细分要求进行递归分解,最终生成规则的栅格点,最后利用波前法的原理生成三角形网格,通过合并处理生成三角形与四边形混合网格。 相似文献
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鉴于三角网格在图形系统和工业界广为使用,提出了一种三角网格上曲线等距线的计算方法,其曲线表示为位于三角网格的点序列连接而成的空间折线.首先,利用三角网格特性把原始边离散成多条新边;然后,沿等距方向计算各条新边端点的等距点,同时对导致两相邻的等距边断裂的顶点生成相应的近似等距的"圆弧段";在边等距过程中删除局部无效环;依次连接所有的等距点生成一中间等距线;再在中间等距线中删除全局无效环得到等距线.实验表明,该方法可行且快速有效. 相似文献