Fixed direction hulls is a special convex hull , whose outward normal of facets comes from a fixed direction set . it overcome limitations of other bounding volumes and makes a promise between tightness and simpleness 固定方向凸包是一种特殊类型的凸包，它的所有面方向都来自一个固定的方向集合，它克服了以往包围盒类型的缺点，在紧密性和简单性之间达到了一定的折衷。
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。
To author ' s knowledge , it can remedy the fact that the bezier - shaped displacement reference curves are laid in local hulls in one hand , so that the deformation region can be further and larger ; on other hand , it makes the computation and quality more robust and better 这一方面弥补了受b zier曲线在一个局部凸包内的约束，使得网格顶点可变形的范围更大，另一方面使得计算更稳定、变形后的曲面质量更好。
In quick feasibility checking , a convex hull is applied to check whether a tool orientation is feasible . if the tool orientation by using this algorithm is not feasible , the detailed feasibility checking is developed to detect the global tool interference 在快速检测中，根据参数曲面的凸包特性粗检现行的刀具方向与凸包之间是否存在干涉，若不存在，则刀具方向是可行的；否则，需通过详细检测来进行最终检测。
Based on nonsmooth analysis theory , the viability criterion is verified under the condition that the set - valued mapping in the right hand side is a polytope and the boundary function of the region is subdifferentiable and its subdifferential is a convex hull of finitely many points 当右端集值映射为多面体，边界为次可微函数，且次微分为有限点集凸包时，基于非光滑分析理论，给出了在一点处检验生存性条件是否成立的方法。
This method embeds the source and target polygons in compatible planar triangulations whose boundaries are the magnified convex hull of polygons respectively , then morph the embedded triangulations with the convexity - preserving method for morphing compatible planar triangulations presented in this paper 该方法将初末多边形嵌入到以其放大凸包为边界的同构平面三角网格中，采用本文提出的同构平面三角网格的保凸变形方法对所得网格进行变形。
The primary idea of the acceleration algorithm focus on the boundary of point set . because only the boundary of a point set is the critical to a convex hull , other point needs not considered . but in classical algorithm , all the point takes part in the calculation 加速算法的思想是这样的，对于一个凸包，算法真正关心的是它的边界上的点，其它的点实际上是不需参与运算的，但是在传统的算法中，所有的点都要参加运算，这就会浪费一些不必要的时间。
Relying on the theorem of graham , the sample points are realized the minimal convex hull which computational complexity is o ( nlogn ) . last a new feature extraction - convex - body segmentation and approximation of scattered sample for non - linear classification based on the knowledge of computing geometry and discrete mathematics is presented . new algorithm guarantees that every convex hull is unintersectant . both convex hull between the same classes and convex hull between the different classes are unintersectant 在此基础上,借助计算几何和离散数学等相关知识,为非线性分类问题中的特征提取提出新的思路-散乱样本凸体分割与逼近算法,算法保证了两类样本形成的凸包两两互不相交,即同类样本之间、同类和异类之间形成的凸包互不相交,并且凸包数量逼近最少,为非线性分类提供了新的研究思路。
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
The acceleration algorithm can calculate a boundary , close in a big part of point , but closed in by the convex hull . afterward , using less time remove the point closed in from point set . according to the research and test , only very little point is keep down 加速算法能够使用简单的方法找到一个凸包的边界，这个边界被真正的凸包所包围，而凸包的大部分点都被这个边界所包围，并且可以知道这些点不可能成为最后凸包的顶点，然后再使用较少(远远小于o ( nlogn ) )的时间去掉这些点。
