参数化

Then,it discusses the method of Parametric Design of E·P and Boolean operation in the parametric design.

阐述了建立电除尘器参数化模型的意义，介绍了ANSYS参数化设计语言APDL、ANSYS命令流及电除尘器的结构特点，并讨论了电除尘器参数化建模的方法及参数化建模中的布尔运算。

Parametric model of brake pad and parametric design of brake shoe have been accomplished on the base of parametric method, secondary development tools on UG, the method of setting environment variables about development system and establishing method of application program, and which can provide the foundation for the development platform of automotive brake system.

对鼓式制动器的组件进行了离散化处理，在介绍了参数化方法、UG二次开发工具、开发系统环境变量的设置以及应用程序创建方法的基础上，完成了鼓式制动器垫片参数化模型的建立以及制动蹄的参数化设计，为汽车制动器专用开发平台的建立奠定了基础。

This thesis contributes to geometry compression in the following aspects: Proposes a method of progressive spherical mesh parameterization based on local parameterization by directly projecting the deleted vertices to its neighborhood. Based on spherical mesh paramterization, an adaptive subdivision remeshing method by progressivly redistributing of sampling points is proposed, by this means, the main geometry information of the original mesh can be captured with only a small amount of samples, it can also be used in mesh simplification. By regarding attributes binded on mesh vertices as geometry signals and transferring them onto a uint sphere by means of spherical mesh parameterization, meshes with different attributes are compressed with spherical wavelet successfully with high compression rate. As a kind of lossy geometry compression technique, two mesh simplification algorthimes are also presented in this thesis.

归纳起来，本文的主要贡献有：提出了以直接投影局部参数化方法为基础的网格累进球面参数化方法；在网格球面参数化方法的基础之上，提出了一种基于累进优化布点方案的网格细分采样方法，该方法可以用很少的采样点就可以捕获到网格的主要特征，因此我们也将其用于后面的网格简化工作当中；通过将网格顶点上定义的各种属性看成几何信号，并以网格球面参数化为手段将几何信号迁移到单位球面上，从而成功地实现了用球面小波对各种几何信号的压缩；作为一种有损压缩方法，本文还提出了基于统一距离的网格简化算法和基于重采样的网格简化算法。

The method involves an iterative procedure, which incrementally flattens a 3D triangular mesh by region growing and obtains a parameterization with free boundary. The result is then converted to a parameterization with regular boundary by conformal mapping. Our method accounts for both the angle and area distortion during parameterization, it yields a parameterization with less global distortion and no triangular flipping.

采用区域增长算法逐层展平空间三角网格，得到空间三角网格曲面的自由边界的参数化结果，并利用保形变换将自由边界的参数化结果变换为规则边界的参数化结果；同时兼顾了参数化的角度变形和面积变形，使得参数化结果具有整体变形较小的特点，并能够避免三角形折叠的现象。

Based on the summarizing of the exiting algorithms of the texture mapping and antialiasing, this paper goes deeply into the basic theory and processing of texture mapping. The texture compress algorithm which can satisfy the need of the memory and time is given for the stochastic sampling in the inverse texture mapping; the geometry transformation in the texture mapping are discussed and the concepts of the unitary parametrization and the patch parametrization is proposed, some kinds of the unitary parametrization methods of parametric surfaces and the geometry transformation in the patch parametrization are also presented; in order to solve the aliasing in the parametrization of intermediate surface-sphere in two-part texture mapping, an area-preserving transformation is presented also; to improve the quality of the graph the aliasing in the texture mapping is analyzed from the aspect of signal process, and the modified summed-area tables algorithms is proposed; the distortion of the scanline conversion algorithms under perspective transformation is analyzed and the proper interpolation algorithm is presented so the aliasing problem of the polyhedral object after the unitary parametrization is efficiently solved.

本文在总结现有的纹理映射和反走样算法的基础上，深入研究了纹理映射的基本原理与过程，根据反向纹理映射对纹理随机采样的特殊要求，提出了一种可满足存储空间和寻址时间的纹理压缩存储算法；通过对纹理映射中几何变换理论的进一步深入探讨，提出了整体参数化和面片参数化的概念，并给出了参数化曲面的各种整体参数化方法和面片参数化的几何变换形式；针对现有的两步映射算法所存在的中间曲面—球面的参数化问题，提出一种等积映射方法，较好地实现了由非参数化面片拼接而成的多面体表面的纹理映射；从信号采样的角度深入分析了纹理映射中走样产生的原因，提出了改进的区域求和表算法，使图形生成的效果有所提高；还分析了一般的扫描线算法在透视变换中所存在的问题，提出了一种正确的插值算法，从而解决了整体参数化后多面体表面纹理映射的几何变形问题。

Space curve is one of the basic elements in geometric modeling, and its effective representation is the basis of modeling. Parametric representation based on features is a kind of high-level representation including semantic information. In Chapter 4, para- metric representations based on features for free form space curve are investigated, and a parametric model for the loop of plain knitted fabric is established, in which 5 parameters with practical meanings are used to represent the shape of a loop and the relationship between loops. A new shrinkage prediction method for knitted fabric are proposed based on the parametric representation and energy minimizing. Experimental results on some plain knitted fabrics illustrate the feasibility of the proposed method.

空间曲线是造型中最基本的几何元素之一，对其有效的表示是造型的基础，而特征参数化表示是其中一种包含语义信息的高层次表示，本文对空间自由曲线的特征参数化表示进行研究，建立了一种针织物线圈的特征参数化几何模型，采用5个具有实际意义的参数表示织物线圈的几何形状及线圈之间的位置关系，并将该模型与能量极小化的方法相结合，得到了一种能较好地预测针织物缩水率的新模型，对随机选取的一些针织布缩水预测实验表明了算法的可行性。

Part five discusses 3D model parametric representation, which includes 3D geometry parametrization and relative position relationship parametrization. In the former, the sweeping rules are further formalized, the concept of design parameters and modeling parameters is introduced. In the later, constraint transformation matrices of the position relationships between features are deduced, and the lost of model freedom resulted from the correspending constraint is analysed.

在特征几何参数化中，进一步规范化了特征几何的扫描生成规则，引入了设计参数和造型参数的概念，分析了造型参数向设计参数适时转化的必要性；在相对定位约束参数化中，推导了特征间一般位置约束关系的约束变换矩阵，拓宽了约束表示范围，并对约束的自由度亏损情况进行了分析。

Our idea of easy dimensional driving includes mainiy:(1) a driving mechanism of construction constraints and dimensional constraints,(2) automatic graphic recognition of constraints,(3) a bothway cross dimensional linked list for storing dimension sparse matrices and for recalling them,(4) a reasonable method of constraint consistence checking,(5) the linking of movement of 2D views,(6) a method for creating a sequence graphic library.

随着二维与三维设计技术的交叉发展，目前的参数化设计主要有两个分支：①面向纯二维的图形参数化，其特点是二维图形为多拓扑环的复杂图形；②面向三维的基于CSG特征造型的参数化，用于拉伸扫描的单拓扑环的二维图形参数化及空间任意曲面的参数化是其特点。

Established databases of pruduct information, design parameters and design results. Explained realization methods of pruduct information and parametric fast design. Established 3D parameter models under the platform of SolidWorks 2001 and realized fast 3D parameter drawings of cyclon.

建立了产品介绍、设计参数和设计结果数据库；阐述了产品介绍和参数化快速设计的设计方法；在SolidWorks平台下，建立三维参数化模型，利用设计结果数据库的数据建立系列零件列表，实现了旋风分离器的三维参数化快速绘图。

Methods of parametric modeling and analysis supplied by ADAMS/View were used to design and analyze front independent suspension of 6 × 6 off-road vehicle, and better results were received.

采用ADAMS／View提供的参数化建模及参数化分析方法，对6 6越野汽车前独立悬架进行了参数化设计，并对悬架主要的几何参数进行了分析，得出了较好的分析仿真结果。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。