Feature - based modeling is adopted on the base of analysis for both geometrical modeling and feature - based modeling . combining the modeling of products in solidworks , an improved modeling method is presented . in chapter 4 , the interactive process design flow of ppdcs is studied based on the specialty of ic lead frame 第三章主要分析cad系统中产品几何造型方法与特点，基于特征造型方法研究现状及特点以及基于特征技术的级进模cad系统；提出本系统中的产品模型建立方法；分析solidworks所采用的特征设计方法。
The key techniques for reverse engineering based on ct image are introduced . 3d reconstructed surface model does n ' t possess full geometry and topology information as solid geometry model . this dissertation presents an algorithm for rebuilding solid model from triangulated patch surface mod 介绍了基于ct图象反求的主要技术；针对重建三维表面模型不具备象实体几何模型的数据那样的完备信息的特点，提出一种基于ct图象的反求技术的实体几何造型方法，将重建模型转换为边界表示的实体模型，并将其作为本研究所开发的特征造型系统3dmodeler中的一种反求工程实体造型手段。
And by a machine configure file , the general postposition process is dealed with . at last , from the view of software engineering , the structure of this system is introduced . according to the achievements , nc automatic programming for noncircular surface gringding based on acis is successfully developed . the result of application shows that it is satisfying 在上述研究成果的基础上,设计了基于acis几何造型平台的非圆曲面数控磨削自动编程系统的总体结构,同时,运用面向对象的设计方法,开发了基于acis的非圆曲面数控磨削加工自动编程系统,并运用于实际生产,性能稳定,效果良好。
Particularly , the parameterized design technology of three - dimensional configuration , the woodward panel method calculating aerodynamic performance , the pixel method calculating the rcs of target ' s surface , the shooting and bouncing race ( sbr ) method calculating the rcs of cavity , and the phase coupling method calculating the rcs of whole missile are researched in this paper 主要应用研究了用于巡航导弹的参数化三维几何造型技术、计算气动性能的伍德沃德面元法、计算目标体表面rcs的象素法、计算腔体rcs的射线跟踪法与计算整体rcs的相对相位叠加法。
2 ) for making the meshes consistent on the common boundaries of adjoining surfaces , a new approach of boundary discretization is employed . 3 ) the boundary - representation structure is adopted to fulfill the mesh generation over combined surfaces . 4 ) the quality of surface meshes is improved by point creation on 3d scan lines and diagonal swapping procedure 通过引入可移动的虚边界解决了闭合曲面的剖分问题；通过对邻接曲面公共边界的统一处理，保证了组合曲面拼合处网格的相容性；以边界表示数据结构为基础实现了三维组合曲面的全自动网格剖分；采用空间扫描线布点、诊断交换等技术，优化了网格的质量；并以autocad为支撑平台objectarx为开发工具，开发了一个基于几何造型的曲面三角形网格全自动生成程序。
As a fundamental work of the numerical calculation , chapter 2 geometrically sculpts the body lines and surface of ship hull using an interactive method and adopts the format of nurbs . the vertexes are directly used by the latter numerical calculation , which avoids the tedious work of data inputting and processing in the traditional cfd programs 作为数值计算的基础性工作，第2章采用人机交互的方式对船体型线与船体曲面进行几何造型，并全部统一成非均匀有理b样条形式，所生成的网格顶点直接为后续水动力的数值计算利用，这样避免了传统水动力计算程序中的许多数据输入和处理的过程。
Nowadays , 3d modeling and computer animation have got widely applications , such as entertainment industry , man - machine interaction , multimedia , communication etc . the third dimension head portrait has been applied to correlative areas , for examples , movie special effects , virtual conference call , internet increment business , mobile internet increment business and software operation interface etc . in the fields of geometric modeling and computer animation , the deformation technology is an important tool 今天,在娱乐产业、人机交互、多媒体、通讯等领域中三维建模和动画获得了越来越广泛的应用。真实感的三维头像可以应用于诸如电影特技、虚拟电话会议、互联网增值业务和移动互联网增值业务以及软件操作界面等相关领域。在几何造型和计算动画领域中,变形技术已经成为一种越来越重要的工具。
