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基于平面离散曲线序列的三维几何结构识别
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作者 冯兰芳 惠延波 《郑州工业高等专科学校学报》 2002年第4期5-8,26,共5页
提出了一种由分层离散曲线序列识别物体三维特征的方法,定义了一些能够表达平面曲线基本特性的特征,设计了用于识别物体三维结构的特征函数,基于这些特征函数,物体被分解为柱体、锥体和曲线体的组合,给出了一些具体应用实例。
关键词 离散曲线序列 平面曲线 特征函数 三维几何结构识别 计算机图形学
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用空间群推导三维编织的几何结构 被引量:5
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作者 马文锁 朱建勋 +1 位作者 蒋云 杨朝坤 《材料科学与工程学报》 CAS CSCD 北大核心 2010年第5期653-657,687,共6页
三维编织复合材料的几何结构和性能研究主要集中在四步法、二步法三维编织,包括以这两种编织方法为基础在不同方向增加增强纱的多向编织方法。本文论述用点群、点阵和空间群推导三维编织几何结构的方法。用编织点群、平移群和点式空间... 三维编织复合材料的几何结构和性能研究主要集中在四步法、二步法三维编织,包括以这两种编织方法为基础在不同方向增加增强纱的多向编织方法。本文论述用点群、点阵和空间群推导三维编织几何结构的方法。用编织点群、平移群和点式空间群的矩阵表示对代表性纱线段进行变换,可以推得三维空间纱线交叉几何结构。研究结果表明,用该方法不仅可以验证原有三维编织几何结构的对称性,而且还可以推导出新的三维编织几何结构,为新三维编织方法的开发研究提供了理论支持。 展开更多
关键词 三维编织几何结构 矩阵表示 理论推导
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基于视觉测量技术构建针织线圈三维结构
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作者 闫超群 杨昆 《针织工业》 北大核心 2014年第12期9-11,共3页
采用视觉测量技术中的三角测量原理对针织物线圈进行直接取点测量,并根据光学几何理论提取出纬平针织物线圈上所选取特征点的三维几何坐标值,依据这些点的坐标使用相关数学软件构建出针织物线圈的三维几何模型。这种研究方法是对针织物... 采用视觉测量技术中的三角测量原理对针织物线圈进行直接取点测量,并根据光学几何理论提取出纬平针织物线圈上所选取特征点的三维几何坐标值,依据这些点的坐标使用相关数学软件构建出针织物线圈的三维几何模型。这种研究方法是对针织物线圈三维几何结构特性的直接反映,避免了使用传统的几何假设方法进行理论推导时对线圈的过于理想化的假设,能够比较真实地反映出纱线在线圈中的空间形态以及针织物线圈之间的串套效果。在获取线圈几何结构的基础上,通过实验进行验证,证明了其准确性。 展开更多
关键词 纬平针织结构 三维几何结构 视觉测量 线圈长度
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Rapid Texture Mapping from Image Sequences for Building Geometry Model 被引量:1
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作者 ZHANGZuxun WUJun ZHANGJianqing 《Geo-Spatial Information Science》 2003年第3期8-15,31,共9页
An effective approach, mapping the texture for building model based on the digital photogrammetric theory, is proposed. The easily-acquired image sequences from digital video camera on helicopter are used as texture r... An effective approach, mapping the texture for building model based on the digital photogrammetric theory, is proposed. The easily-acquired image sequences from digital video camera on helicopter are used as texture resource, and the correspondence between the space edge in building geometry model and its line feature in image sequences is determined semi-automatically. The experimental results in production of three-dimensional data for car navigation show us an attractive future both in efficiency and effect. 展开更多
关键词 image sequences video camera on helicopter 3D reconstruction texture mapping digital photogrammetry
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A New Method for 3D Finite Element Modeling of Human Mandible Based on CT Data 被引量:1
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作者 于力牛 叶铭 王成焘 《Journal of Donghua University(English Edition)》 EI CAS 2004年第1期29-33,共5页
This study presents a reliable method for the semi-automatic generation of an FE model, which determines both geometrical data and bone properties from patient CT scans.3D FE analysis is one of the best approaches to ... This study presents a reliable method for the semi-automatic generation of an FE model, which determines both geometrical data and bone properties from patient CT scans.3D FE analysis is one of the best approaches to predict the stress and strain distribution in complex bone structures, but its accuracy strongly depends on the precision of input information. In geometric reconstruction, various methods of image processing, geometric modeling and finite element analysis are combined and extended. Emphasis is given to the assignment of the material properties based on the density values computed from CT data. Through this technique, the model with high geometric and material similarities were generated in an easy way. Consequently, the patient-specific FE model from mandible CT data is realized also. 展开更多
关键词 Computed Tomography MANDIBLE Three-Dimensional Finite Element Analysis
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Structural Mechanics Analysis Using an FE-Mesh Adaption to Real, 3D Surface Detected Geometry Data
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作者 Sebastian Katona Michael Koch +1 位作者 Tobias C. Spruegel Sandro Wartzack 《Journal of Mechanics Engineering and Automation》 2015年第7期387-394,共8页
Within today's product development process, various FE-simulations (finite element) for the functional validation of the desired characteristics are made to avoid expensive testing with real components. Those simul... Within today's product development process, various FE-simulations (finite element) for the functional validation of the desired characteristics are made to avoid expensive testing with real components. Those simulations are performed with great effort for discretization, use of simulations conditions, like taking different non-linearities (i.e., material behavior, etc.) into account, to create meaningful results. Despite knowing the effects of deformations occurring during the production processes, always the non-deformed design model of a CAD-system (computer aided design) is used for the FE-simulations. It seems rather doubtful that further refinement of simulation methods makes sense, if the real manufactured geometry of the component is not considered for in the simulation. For an efficient exploit of the potential of simulation methods, an approach has been developed which offers a geometry model for simulation based on the existing CAD-model but with integrated production deviations as soon as a first prototype is at hand by adapting the FE-mesh to the real, 3D surface detected geometry. 展开更多
关键词 FEA (finite element analysis) PREPROCESSING simulation 3D surface detection RE (reverse engineering)
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基于空间群P对称性的一种新型三维编织材料 被引量:1
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作者 马文锁 任小中 《科学通报》 EI CAS CSCD 北大核心 2011年第8期598-603,共6页
用点群S6对应的对称操作推导出一种新的三维编织几何结构单胞.根据空间群P描述的对称性,对新的单胞进行对称变换获得了一种新的三维编织几何结构,研究了这种三维编织几何结构可行的编织工艺.通过建立其几何分析模型,预测了对应三维编... 用点群S6对应的对称操作推导出一种新的三维编织几何结构单胞.根据空间群P描述的对称性,对新的单胞进行对称变换获得了一种新的三维编织几何结构,研究了这种三维编织几何结构可行的编织工艺.通过建立其几何分析模型,预测了对应三维编织材料的纤维体积百分含量及其变化趋势. 展开更多
关键词 点群S6 空间群P3 三维编织几何结构
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