共查询到19条相似文献,搜索用时 62 毫秒
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针对传统逆向工程技术所重构的B-rep模型信息表达层次低、无法体现设计意图、难以实现改型设计和再设计的缺陷,提出一种面点云数据直接重构特征模型的策略,并对其中点的微分几何性质估算和拉伸旋转面特征重建等基础而关键的步骤提出一套解决算法,以传统坐标转换法估算的法矢为初值,通过引入迭代来提高法矢曲率的计算精度,依据拉伸旋转面的特殊几何性质,利用随机抽样一致性算法提取拉伸方向和旋转轴,实验结果证明了算法的有效性、精确性和鲁棒性,为特征模型重构的下游计算奠定了良好的基础。 相似文献
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基于B样条曲面的点云孔洞拟合填充 总被引:1,自引:0,他引:1
为了后续曲面重构的需要,针对有孔洞的点云数据,提出了一种孔洞拟合填充的自适应方法.由于孔洞与其周围离散点有一定的连续性,该算法首先从孔洞周围已有的点云数据中选取离散点,用新的参数化方法对得到的离散点参数化后,用最小二乘法进行自适应曲面拟合,对得到的拟合曲面通过迭代法逐步逼近优化,考虑曲率变化的影响在曲面上取点,实现了孔洞光滑填充.实例表明,改进的参数化方法使算法的复杂度减低,进一步迭代优化提高了曲面拟合精度,在面上取点时考虑了曲率变化,因此该方法可以应用于具有复杂曲面形状的点云中的孔洞填充. 相似文献
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基于B样条曲面的点云孔洞拟合填充 总被引:1,自引:0,他引:1
为了后续曲面重构的需要,针对有孔洞的点云数据,提出了一种孔洞拟合填充的自适应方法。由于孔洞与其周围离散点有一定的连续性,该算法首先从孔洞周围已有的点云数据中选取离散点,用新的参数化方法对得到的离散点参数化后,用最小二乘法进行自适应曲面拟合,对得到的拟合曲面通过迭代法逐步逼近优化,考虑曲率变化的影响在曲面上取点,实现了孔洞光滑填充。实例表明,改进的参数化方法使算法的复杂度减低,进一步迭代优化提高了曲面拟合精度,在面上取点时考虑了曲率变化,因此该方法可以应用于具有复杂曲面形状的点云中的孔洞填充。 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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提出了基于三角化模型截面线提取产品特征线的四边域曲面重构的方法.该方法不但对特征点提取进行了降维简化,把在三维数据点云中直接求取特征点,转化为在截面线上求点,而且综合了三角曲面法快速、灵活、边界适应性好和四边曲面法精确、光顺的优点. 相似文献
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在实物零件数字化过程中,截面点云是比较常见的一种表现形式。由截面点云拟合截面曲线,进而得到零件曲面在实践中有着广泛的应用。曲面的曲率反映了曲面的几何属性,也是进行质量评估以及产品设计的关键技术之一。通过计算机图形显示技术,对拟合后的曲面进行曲率可视化分析,不仅可以直观地评价曲面的光顺情况,也可显著地提高工作效率,为工作人员提供了一种可视化手段。以叶片为研究对象,实验表明:曲率彩色云图能使用户方便地了解整体及局部的曲率分布信息,便于用户进行计算机辅助设计、改善曲面的设计质量等。 相似文献
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针对由激光三维扫描设备获取的点云数据及其后续RPM操作,提出基于栅带的自由曲面点云自适应分层方法.以栅带为基元,将点云投影栅带化,从中获取特征点集,结合相邻栅带距离最小值点找寻构建层间轮廓.定义投影点云栅带面积比为表面误差,建立其与堆层厚度的关系,通过表面误差逼近定值最终确定堆层厚度.经实例验证,此方法得到的分层模型充分满足RPM的要求. 相似文献
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Y. Choi K. Kim S. Lee 《The International Journal of Advanced Manufacturing Technology》2003,21(6):446-451
Given only a set of points, without any geometric information such as the adjacency among the points, the scanning order or
the scanning direction, it is a difficult problem to reconstruct a surface model corresponding to the original shape. For
the reconstruction of open shapes, many effective approaches have been proposed. It is, however, hard to find a robust and
effective method for the reconstruction of closed shapes. In this paper, an algorithm is proposed to reconstruct a three-dimensional
closed shape from a set of good sample points using the properties of Delaunay triangulation and Voronoi diagrams. The proposed
method consists of three steps; (1) constructing a convex hull consisting of mutually exclusive tetrahedra by 3D Delaunay
triangulation of input points, (2) generating a Voronoi diagram of input points by utilising the properties of Delaunay triangulation,
and (3) extracting the triangles on the shape boundary, defined by input points, after selecting the tetrahedra which are
contained inside the shape using the properties of Voronoi diagrams. The proposed method in this paper has some advantages
compared to the previous approaches. First, the distance parameter, such as α in the α-shape approach, is not required in the proposed approach. The determination of a proper parameter by trial and error is not
appropriate, especially in the automation of shape reconstruction. Secondly, the time complexity of the proposed approach
is O(n) since, in a single pass, this algorithm determines whether each tetrahedron is located inside or outside the shape boundary.
ID="A1"Correspondance and offprint requests to: Dr K. S. Kim, Department of Industrial Engineering, Pohang University of Science and Technology, San 31, Hyojadong, Pohang,
790–784, Korea. E-mail: kskim@postech.ac.kr 相似文献
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The development of a technique for 3D complex surface reconstruction from unorganized point cloud 总被引:1,自引:0,他引:1
Viboon Sangveraphunsiri Kiattisak Sritrakulchai 《The International Journal of Advanced Manufacturing Technology》2007,33(7-8):772-781
In this paper, we propose a new neural network based on our two-level adaptive hierarchical clustering algorithm. The algorithm
is to manage unorganized points, so that the triangular mesh models can be correctly obtained by applying the triangular mesh
creation algorithm. We also develop adaptive self-flipping triangle edges to improve triangular mesh structure. Only one parameter,
the maximal edge length of triangle, is needed in the neural network. The proposed two-level consists of the first level for
clustering the cloud of points that has same order of the maximal edge length into a same cluster and the second level for
generating triangular surface model or drape surfaces over the points of the same cluster. The normal vector for the generated
triangular 3D surface model can be obtained from the second level. This helps to generate the STL file or stereolithography
format. From the experimental results it can be shown that the proposed method is very effective for clustering unorganized
point clouds for generating a triangular mesh of complex surfaces. 相似文献
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针对现有曲面重建神经网络算法误差大的缺点,并根据广义回归神经网络解决函数逼近问题的特点,提出了一种针对点云曲面重构的广义回归神经网络,并编制Matlab程序对点云曲面做了仿真试验;仿真结果表明:该模型逼近曲面误差精度达到网络设计要求的10~(-4)mm,网络学习速度快,重建曲面光顺. 相似文献
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逆向工程中扫描数据点的曲面重构 总被引:3,自引:0,他引:3
针对三维扫描数据点的曲面重构技术在实际系统中的应用,提出了一种以B样条曲面为基础的曲面构造算法。已知数据点按简明行方式排列,算法产生一个连续的B样条曲面,该曲面的参数化过程不受每行数据点分布的影响。根据所传递的候选节点矢量,采用柔性间距选择,有效地减少了控制顶点数,同时应用三维图形标准以及图形函数库,在VC 6.0平台上完成了该软件的编制。通过实际系统应用验证,该算法改进了传统曲面重构方法在处理非均匀扫描数据点时曲线曲面形状的失真和运算的不稳定现象,计算简单,易于编程实现。 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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逆向工程在产品曲面重建中的应用研究 总被引:2,自引:0,他引:2
逆向工程(反求工程)是CAD/CAM领域的一个研究热点,特别在工业设计学科产品外形设计的领域中得到了广泛的应用.目前产品复杂曲面重建的方法通常采用分片的小曲面片来拼接形成整张曲面,这种方法无法提取曲面的特征.本文针对复杂曲面重建这一难点,着重分析比较了逆向工程中经典的曲面重建方式,并在此次基础上提出了以点云-曲线-曲面为步骤的CAD模型整体重建方案以完成整个模型的重建过程,并用鼠标的实例综合验证了这一方法在曲面重建应用中的可行性. 相似文献