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曲面重构中测量点云精简方法的研究 总被引:6,自引:0,他引:6
反向工程研究中,根据三维测量数据进行曲面重构是其关键技术之一。介绍了曲面曲率的基本理论,根据曲率精简点云的方法及曲率估算的方法,并结合实际对根据曲率精简测量点云数据的方法进行了改进,着重研究了邻域搜索、曲率估算、曲率精简原则等,在保证测量精度的前提下,在提高曲面重构的计算效率、减少存储空间等方面取得了较好的效果。 相似文献
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针对摄影测量过程及所得点云数据的特征,利用模板法计算曲面曲率以确定曲面的精简比,对曲率图像进行非均匀网格滤波,实现了对摄影测量点云数据的精简。计算过程简洁方便,实验结果保持了原有数据的形态。该方法适用于摄影测量点云数据的后期处理。 相似文献
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在三维测量点云数据与CAD模型配准过程中,设计了两种自由曲面CAD模型点云数据生成方法:等参数采样离散法和基于曲率的采样离散法。应用两种方法评价离散化结果:首先将点云数据进行曲面重构,并与原曲面比对;然后与三维测量点云数据进行配准,得到等参数离散间隔及基于曲率的离散密度对重构和配准误差的影响。实验表明:等参数方法和基于曲率的方法,当点云数据密度达到一定值时均对重构和配准没有影响;在同样点云数据的情况下,基于曲率的离散化方法精度高于等参数方法;但在最大重构误差一致时,基于曲率的方法需要的点云数据远小于等参数化方法所需要的。 相似文献
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复杂曲面点云简化时,通常存在特征点丢失问题;提出按照点云曲率云图自动划分特征区域实现非均匀简化。首先建立散乱点云拓扑关系,计算点云曲率,生成彩色曲率云图,之后划分特征区域边界。精简率随着曲率的减小而增大,在复杂细节特征点区域,点云密度大;在简单平坦区域,点云被大量简化,点云密度小。实验表明,精简率达76%,在精简率相同的情况下,该方法能有效避免局部细节特征丢失,对于复杂曲面点云简化有较好的效果。 相似文献
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反求工程中过渡曲面特征提取算法研究 总被引:16,自引:1,他引:16
针对反求工程中常见的过渡曲面特征,提出了一种过渡曲面特征的提取算法。该算法包括数据分块和过渡曲面参数提取两部分,在数据分块算法中,通过数据精简,曲率估算和曲率比较等步骤,将过渡区域的数据点从原努点云数据中分离出来,在过渡曲面参数提取算法中,通过圆柱拟合和过渡区域跟踪算法,计算出一系列过渡曲面的截面线,该算法和已有的过渡曲面特征提取算法相比,无需人工交互,而且适用于等半径过渡曲面特征和变半径过渡曲面特征。 相似文献
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由于三维扫描设备采集的点云数据庞大,本文提出了一种特征保持的点云精简方法以在减少冗余数据的同时更好地保持原始曲面的几何特征。首先,利用K均值聚类法在空间域对点云全局聚类,对点云构建K-d树并以K-d树的部分节点作为初始化聚类中心。然后,用主成分分析法估计点云法矢和候选特征点,遍历每个聚类,若类中包含特征点则将该类细分为多个子类,细分时将聚类映射到高斯球。最后,基于自适应均值漂移法对高斯球上的数据进行分类,高斯球上的聚类结果对应为空间聚类细分结果,各聚类中心的集合为精简结果。以多个实物模型为例验证了算法的有效性。结果表明,本文方法精简的点云在平坦区域保留少数点,在高曲率区域保留更多的点。相比于非均匀网格、层次聚类、K均值点云精简法,该方法对包含尖锐特征的曲面精简误差最小,更好地保留了原始曲面的几何特征。 相似文献
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《Measurement》2014
In this paper a methodology to compare two point clouds of an object, obtained with different equipment or in different conditions, is proposed. First, the point clouds are registered to the same reference system using an iterative algorithm that performs a rigid body transformation. Then, the standard deviation of the measurements is estimated, in order to evaluate the uncertainty in the measurements. Afterwards, two surfaces are adjusted to each of the point clouds by means of a kernel smoothing technique and compared. Finally, the effect of uncertainty in the point coordinates is considered by means of a bootstrap analysis.The methodology was used to compare two point clouds of a beam bridge measured using two different types of terrestrial laser scanner (time-of-flight and phase-shift based systems). According to the results obtained, some statistically significant differences exist between both point clouds. 相似文献
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K. Schreve A.H. Basson 《The International Journal of Advanced Manufacturing Technology》2005,26(9-10):1048-1054
This paper describes an algorithm for edge detection in reverse engineering applications. This algorithm is able to detect edges in unstructured point clouds, and also reconstruct the “original” sharp edge in point clouds scanned on objects with broken, worn or filleted edges. Edges can be detected from point clouds without a priori compensation for the probe radius. When combined with a swept surface approximation algorithm, these surfaces can be used to segment some point clouds. These capabilities make this algorithm a valuable tool in the reverse engineering of machine components such as the inlet manifold used as a case study. 相似文献
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为获取外形不规则且具有复杂形状内腔的挖掘机斗齿形状、尺寸等数字信息,基于实物反求工程技术路线,对其进行逆向设计曲面重构技术研究.对曲面反求过程中的数据采集、对齐点云、数据分割及曲面重构等环节有系统的分析总结,对型面数量多的斗齿点云进行了有效的数据分割,提出了基于零件结构特征的直接交互式点云分割法,且反求得到的斗齿曲面精度满足要求,该方法对复杂内型面零件的反求有一定的借鉴作用. 相似文献
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Sun Yuwen Guo Dongming Jia Zhenyuan Liu Weijun 《The International Journal of Advanced Manufacturing Technology》2006,27(9-10):918-924
The issue of surface reconstruction and slicing from point clouds has been receiving extensive attention recently. When using the B-spline surface fitting technique, the difficulty of parameterization exists. At the same time, for interfacing between reverse engineering and rapid prototyping, the point clouds are usually converted to an stereolithography (STL) model. This leads to a huge file size and requires expert modeling skills. The objective of this work is to establish a base surface parameterization and direct slicing strategy for scattered data based on a cross-sectional design technique. We first present a new method of directly extracting sectional contours from point clouds. Then, we create a base surface by skinning the primary boundary curves and interior sectional curves. Based on a good parameterization, the final surface is achieved with tight tolerance. Several practical examples have demonstrated the feasibility of the proposed method. It can be widely used in Number Control (NC) machining and rapid prototyping. 相似文献
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论述了从三坐标测量机得到的数据重建模具CAD模型的工作过程,包括点云的预处理如点云对齐、误差点剔除;曲面重构:包括点云的网格化、孔洞填充、边界处理、曲面拟合及曲面评估.利用Geomagic软件完成了对某梁的逆向设计,证明了反求工程理论的可行性. 相似文献
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散乱点云谷脊特征提取 总被引:1,自引:0,他引:1
利用微分"化曲为直"的本质特性和离散计算方法,提出了一种基于局部重建的散乱点云谷脊特征提取算法。首先,利用离散Laplacian算子对点进行增强,通过阈值过滤标记潜在谷脊点。然后,在每个潜在谷脊点的局部邻域内构建紧附于潜在曲面、能反映该点局部几何特征信息的三角网格。最后,根据Weingarten映射的性质,估算潜在谷脊点的主曲率和主方向;将邻域大小作为尺度参数,利用简单直观的离散计算方法及线性插值方法,多尺度地判定一点是否为主方向上的曲率极值点,从而提取谷脊特征。实验结果表明:当点云规模为10 375个,谷脊点规模为1 129个时,执行时间仅为97.39ms;当点云规模达327 853个,谷脊点规模达到105 482个时,执行时间为3 956.12ms。该方法简单、稳定,避免了传统的利用拟合曲面再逼近微分量方法中由于曲面拟合带来的高时间代价,能快速有效地提取散乱点的云谷脊特征。 相似文献
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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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Dong-Jin Yoo Hyuk-Hong Kwon 《International Journal of Precision Engineering and Manufacturing》2009,10(1):103-113
Shape reconstruction from point clouds has received considerable attention in recent years on account of its ability to directly
integrate reverse engineering with rapid prototyping. The primary objective of this study is to develop an integrated system
that enables one to generate input data for rapid prototyping by constructing complete shape models from point clouds obtained
with various measuring devices, including laser scanners, digitizers, and coordinate-measuring machines. We first present
a novel approach to reconstructing a shape from point clouds based on implicit surface interpolation combined with domain
decomposition. We then propose various related algorithms for generating input data for rapid prototyping, ranging from shape
manipulation to complete solid generation. The validity of this new technique is demonstrated for a variety of point clouds
with differing degrees of complexity. 相似文献