基于人体截面点云的围度尺寸计算  

Calculation of circumference size based on human body section point cloud

作　　者：李晓志[1] 李晓久[1] 刘皓[1] LI Xiaozhi;LI Xiaojiu;LIU Hao(School of Textile Science and Engineering, Tianjin Polytechnic University, Tianjin 300387,China)

机构地区：[1]天津工业大学纺织科学与工程学院

出　　处：《纺织学报》2019年第7期128-132,共5页Journal of Textile Research

摘　　要：为简化围度尺寸计算过程,首先将三维人体截面点云转化到平面坐标系内,然后采用快速比较法获取点集中的4个极值点,并根据极值点将点集分成4个子区域,根据每个子区域点集的凸包具有单调性这种特性,对区域内点集的x和z坐标值进行排序比较去掉部分凹点,再通过计算点与相邻2点组成向量的叉积判断其夹角范围获取截面凸包点,将最终凸包点连接起来即为人体围度尺寸。结果表明:本文方法与 Graham 扫描法相比,二者时间复杂度相同,计算结果一致,但本文方法在程序上更容易实现,且通过简单的排序比较法简化初始点集可减少凸包顶点回溯迭代次数,从而提高计算人体围度尺寸的效率。In order to simplify the calculation process on the circumference size, the coordinates of section points in space were first transformed to 2-D plane. Then by the quick comparing sorting, four extreme points were acquired, and based on the extremes points the point set was divided into four subsets. The convex hull of every subset was monotonous, so some concave points were directly deleted by sorting and comparing the coordinates x and z. The final convex hull points were determined by the inner angle of the adjacent three points calculated by the cross product. The line by connecting the points in order was the body circumference line and its length was the size. Comparing with the Graham scanning method, the method has the same time complexity and same results. However, it is easier to be programmed, and by simplifying the point set by easily sorting and comparing, the method can reduce the number of backtracks and effectively improve the computing efficiency of body′s circumference sizes.

关 键 词：人体截面 平面点集 围度尺寸 凸包 向量积 

分 类 号：TP391.72[自动化与计算机技术—计算机应用技术]