【作者】 高斌；

【导师】 俞小莉； 胡树根； 宋小文；

【作者基本信息】 浙江大学 ， 车辆工程， 2006， 博士

【摘要】 车身曲线曲面设计质量极大地影响车身外观，影响人们对整车的第一印象，从而影响汽车在激烈市场竞争中的竞争力，因此，在车身设计过程中，如何方便、有效地对曲线曲面质量进行检测与修正一直是工程设计人员和该领域研究人员追求的目标。 本文在深入剖析国内外相关技术研究现状基础上，对计算机辅助曲线曲面质量检测与修正技术及理论进行了详细、深入的研究： 提出了一套高质量、高效率的面向曲面品质分析的曲面离散技术。在给定曲面最大离散误差、最大网格尺寸、网格边端点的最大法向偏差下，曲面按照三维等距离等参数线网格化后，按照网格边端点的法向偏差标准进行局部网格加密，使之能更好地满足具有局部不光顺性曲面的品质分析与调节需要；充分利用曲面边界信息帮助查找两曲面的公共边界网格，在边界网格连接时根据连接需要直接对被连接的网格进行简化和顶点合并，以提高两曲面公共边界网格的连接效率，减少网格数。 提出了一套快速、高效的曲面品质分析结果等值线生成算法。先计算出网格顶点的场量值，然后根据每条网格边所涉及的顶点判断并确立网格边上的等值点，最后根据三角形网格的拓扑关系追踪每条等值线。本算法中每条网格边的等值点判断、计算和存储只进行一次，每个离散网格顶点的场量值只计算和存储一次，减少了内存消耗，减少了计算量，因而大大提高等值线的生成速度和处理效率，能更好地满足在虚拟环境中交互式检测曲面质量的需要。 提出了一套简单、直观、有效的、基于补丁曲面质量检测线(反射线或高亮线)的NURBS曲面局部光顺算法。在曲面不光顺区域建立光顺的补丁曲面，用补丁曲面的质量检测线替换原曲面质量检测线位于补丁曲面的部分，实现对原曲面质量检测线形状的修改；利用修改后的曲面质量检测线及曲面不光顺区域的边界条件建立曲面局部光顺的线性方程组，求得曲面不光顺区域控制点的位移量，根据曲面不光顺区域控制点对曲面不光顺区域影响程度对各控制点的位移量进行平滑处理，得到经过局部光顺后的新曲面控制点。 提出了一套直观、有效的、基于曲率单调均匀变化约束的平面B样条曲线光顺算法。在总结出平面曲线光顺准则必须考虑曲率单调变化和曲率变化的均匀性基础上，以曲线段离散点列能量最小及和原始曲线误差最小为目标函数，以能反映设计意图的目标曲率云图所提供的信息(各曲线段曲率单调变化趋势)更多还原

【Abstract】 The design quality of curves and surfaces greatly influences the appearance of car body. It affects people’s first impression to the whole car. Thus affect the power of this automobile in the drastic market competition. Therefore, how to effectively detect and modify the quality of curves and surfaces of car body in a simple way during the design process is always the pursuing target of engineering designers and researchers of this field.On the basis of analyzing the present status of the relative technical research in this field in detail, the technology and theory of computer-aided quality detecting and modifying of curves and surfaces has been thoroughly investigated in this dissertation.A set of surface tessellation algorithm facing to surface quality detection with high quality and high efficiency is put forward. Surfaces are tessellated with 3D equidistant iso-parametric lines by parameters of maximum approximation error and maximum grid size. To better content the requirement of surface quality analysis and modification with local unfairness, the density of tessellation is adjusted by parameters of maximum deviation of normal direction along the grid corner. The information of surface boundary is used to check the public boundary meshes of two surfaces. To raise the connection efficiency of the public boundary meshes and reduce the mesh number when sewing up two surface meshes, connected surface meshes are modified by mesh vertex substitute and mesh deletion according to the certain rule and the demand of the boundary mesh connection.A new method is proposed to quickly build contour lines for surface quality analysis. First, every vertex field value is computed. Then, points with equivalent field value on every mesh edge is judged and computed according to the vertexes related to the mesh edge. Finally, a series of ordinal points with equivalent field value are traced to form contour lines according to the topological relation. In this method, the point with equivalent field value on every mesh edge is estimated and stored only once and the field value of each mesh vertex is also computed and stored only once, which save memory occupation and computing cost when creating contour lines. As a result, the speed of making contour lines and the efficiency of processing contour lines are improved greatly. This algorithm can satisfy the demand更多还原