共查询到20条相似文献,搜索用时 9 毫秒
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Robust segmentation of CMM data based on NURBS 总被引:4,自引:1,他引:4
Dr Y. H. Chen C. Y. Liu 《The International Journal of Advanced Manufacturing Technology》1997,13(8):530-534
Segmentation is a crucial step towards the interpretation of discrete three-dimensional measurement data. This paper presents a robust method for compound free-form surface segmentation and reconstruction. In the proposed method, a cloud of measurement data are collected through a coordinate measuring machine (CMM). The set of measurement data is then sliced along, at most, three orthogonal directions. On each slicing plane, measurement data is fitted by a 2D NURBS spline. Now, maximum curvature points on each NURBS spline can be calculated. These points represent the boundary of the digitised object. With the proposed method, three-dimensional segmentation is simplified to a two-dimensional problem. The effectiveness of the proposed segmentation method will be illustrated with examples of a hair drier and a telephone receiver. 相似文献
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Reverse engineering of composite sculptured surfaces 总被引:7,自引:0,他引:7
Dr Jiing-Yih Lai Chiou-Yuan Lu 《The International Journal of Advanced Manufacturing Technology》1996,12(3):180-189
A reverse engineering technique is proposed in this study for modelling composite sculptured surfaces. The proposed technique includes a surface fitting algorithm and a surface blending algorithm. The former is formulated as the least-squares minimisation problem for which an error expression was minimised which yields the optimised position of control points and parameter values for the non-uniform rational B-spline patch. Cubic spline and bicubic surface algorithms are developed for two-patch and four-patch blending, respectively. Computer simulation results clearly demonstrate that the proposed technique is useful for composite surfaces modelling applications. Factors affecting the convergence speed and surface accuracy in the optimisation process are also discussed. 相似文献
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M. J. Milroy D. J. Weir Dr C. Bradley G. W. Vickers 《The International Journal of Advanced Manufacturing Technology》1996,12(2):111-121
An important step in many manufacturing processes is the definition of the three-dimensional form of an object's shape. A common example is the definition of a designer's model created in clay or wood. A three-dimensional laser scanner offers the advantage of speed and non-contact sensing compared to traditional touch probe sensing. The three-dimensional data produced have been used in a multi-patch reverse engineering program in order to model objects where many types of surface patches, such as quadric and free-form, are blended together on one object. The surface reconstruction algorithms have been demonstrated to provide accurate and smooth surfaces that are suitable for CAD database integration and CNC machine toolpath generation. The algorithms have been implemented in an interactive 3D surface modelling program that produces surfaces compatible with current CAD/CAM systems. The application of the technology to the reverse engineering of a typical injection moulded part is described. 相似文献
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Reverse engineering of complex geometry using rational B-splines 总被引:3,自引:0,他引:3
Hong-Tzong Yau Jenq-Shyong Chen 《The International Journal of Advanced Manufacturing Technology》1997,13(8):548-555
Rational B-splines have become the new standard for representing free-form curves and surfaces. This paper presents a method for approximating rational B-splines using digitised data. Instead of using the classical optimisation approach to solve the multivariable nonlinear equations, a new method based on iterations of least-squares solutions and single variable mimimisation is developed. This is made possible by modifying the original objective function to avoid the rational format. Simulation of fitting a 90° arc shows that the algorithm can produce accurate solutions close to nominal values. The efficiency of the algorithm also makes it possible to apply the method to day-to-day reverse engineering problems using rational B-splines. 相似文献
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重点介绍三坐标测量自由曲面的反求技术。通过对自由曲面数字化过程中数据获取、测量数据处理和曲面重构的研究,得到鼠标外壳的三维模型,极大地提高了设计质量和效率。 相似文献
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基于三坐标测量机的数据采集技术 总被引:1,自引:0,他引:1
数据采集是逆向工程建模的关键环节,测量数据的可靠性决定建模的效果和效率。以三坐标测量机为例,介绍逆向工程中利用三坐标测量机进行数据采集的基本过程。 相似文献
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介绍了仿形测量技术和复杂曲面重构技术,运用于发动机气道逆向工程设计实践中。发动机气道外形准确描述为后续CAM/CAE提供了必要基础和支撑,优化后CAD模型用于快速成型加工出样件。 相似文献
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反求技术在搅拌机拌筒叶片三维建模中的应用 总被引:1,自引:0,他引:1
通过反求技术在搅拌机拌筒叶片上的应用,探讨了原形的数字化技术和叶片原形CAD模型的重建技术,解决了 叶片反求过程中的测量技术及曲面构造技术等关键难点技术。 相似文献
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首先介绍逆向工程技术发展历程,随后从基于点云的数据处理、曲面重构(非均匀有理B样条曲面和三角Bezier曲面)、国内外常用逆求软件3个方面阐述了逆求工程研究现状。 相似文献
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