And we hope that the adbf methods at subarray level should possess the quiescent pattern keep ability , so that there is no need to switch between adaptive and non - adaptive operation modes 因而我们希望,子阵级adbf方法具有静态方向图保形能力,从而不必在自适应和非自适应工作模式之间进行转换。
Constrained conditions consist of data interpolations ( interpolations to data points or to one order and curvature at data points ) , shape - preserving interpolation and smoothing or fairing fitting 约束条件包括数据插值(可以是对数据点或数据点处的一阶导和曲率等的插值) 、保形插值和光顺拟合等。
Normalized b - basis , namely optimal normalized totally positive basis , plays an important role in cagd , for it possess positive properties such as variation diminishing , convex - hull , affine invariance , tangency to the control polygon at the endpoints and b - algorithm 规范b基即最优规范的全正基，因其具有凸包性、仿射不变性、最优保形性，端点插值性及b算法等重要性质，在cagd中起着重要的作用。
In the forth chapter , we proposes an approach of constructing planar piecewise bezier curve of 3rd 4th and 6th degree with all edges tangent to a given control polygon and the curve segments are joined together with c1 c2 and c3 - continuity . the segmented bezier curves are all shape - preserving to their tangent polygon 第四章讨论与给定多边形相切的分段三次、四次、六次b zier曲线，所构造的曲线c ~ 1 、 c ~ 2 、 c ~ 3 -连续，并且对切线多边形是保形的。
Firstly , the pretreatment of character to be recognized is researched , stressed discussing the subdivisional process of character , and a kind of fast shape preserving morphological thinning algorithm is used . in the following , how to construct the structure model on the basis of characteristic point ) sub - stroke and their interrelation is discussed , and a kind of method that describe sub - stroke through the feature of the sequence of curvature is brought forward . finally , the paper adopts the recognising model of printing number that base on repository , and describes the constructing method of repository 文中首先对待识别字符的预处理进行了研究，着重探讨了字符的细化过程，采用了一种基于数学形态学的保形的快速细化算法；接着探讨了如何以特征点和子笔段及其相互关系为基础构造结构模型，提出了一种以曲率序列性质描述子笔段的方法：最后采用了以知识库为基础的印刷体数字识别模型，并详细地描述了知识库的构造方法。
Chapter 4 discusses the usage of two basic geometric reconstruction method ( bezier and b - spline surfaces reconstruction ) in virtual cad system based on the milti - hierarchical mesh model . bezier reconstruction method introduces li lixin ' s new c - t algorithms which adopts bezier patches on rectangles . b - spline reconstruction follows floater ' s shape - preserving parametric method using double cubic b - spline surface and extends it into non - four - side areas by inducing corner vertices and optimizing the sheer - shape boundary which amends the boundary distortion of the reconstructed surfaces 通过引入单边退化概念，进行四边域上的bezier曲面重建；通过引入保形参数化映射，讨论双三次b样条曲面重建方法；在网格曲面四边拓扑分析的基础上，给出了基于深度搜索的角点求取方法，拓展了floater双三次b样条曲面重建的应用范围。
According to properties of h - bezier basis , h - bezier curves are endowed with wonderful geometric properties including interpolating at endpoints , convex hull , affine invariance and optimal shape preserving . furthermore , a shape factor of the h - bezier curve is introduced to control the shape of the designing curves 基于h - b zier基函数的几何性质， h - b zier曲线具有适合cad中曲线建模和形状设计的保形性，端点插值性，凸包性，几何不变性和形状控制等很好的几何性质
