基于双次K-means聚类分析的青年女性足型分类

Foot type classification of young females based on double K-means cluster analysis

针对足型分类标准不全面导致的青年女性足类产品与实际足型常常不相符的问题,为合理地对青年女性足型进行分类,文章借助手持式三维扫描仪获取了浙江地区100名18~25岁青年女性的有效足部图像,使用NX Imageware 13软件采集48项足部参数。通过相关分析和回归分析探究足部各参数间关系,利用主成分分析和特征选择提取影响足部尺寸和形态的特征因子与特征指标,采用双次K-means聚类划分青年女性足型,并对比国标号型。结果表明:影响足部尺寸的主成分因子有足长因子、足宽因子和足厚因子,影响足部形态的特征指标为足长、足宽和足弓高度;浙江青年女性足型可分为9类。该研究考虑了跖趾围长的多维度重叠对足型分类的影响,可为鞋楦设计和足部数字化建模等提供参考。

The foot is one of the most important organs of movement in human body.GB/T 3293—2017 Chinese Last Systems is based on Chinese Shoe Sizing and Last Systems written by the Scientific Research Institute of Shoe Industry of the Ministry of Light Industry,which has formulated the Chinese shoe system with the foot length and metatarsal toe circumference length as the classification standard.Due to the development of the lifestyle,the foot size and foot shape of modern people have changed.As a result,the existing foot data cannot satisfy the needs of the production and living.In addition,female shoe lasts are transformed from male lasts;however,there are several distinctions in the morphology and biomechanical structure of male and female feet,which makes a negative impact on the fitness of female footwear products.Therefore,it is important to study female foot type in depth and make some adjustments to the existing standard of the foot classification.In response to the problem that foot size classification criteria are not comprehensive and often do not match the actual foot size of young women and to classify the foot size of young female in a reasonable way,we first obtained valid foot images of one hundred young women aged 18-25 in Zhejiang province with the handheld 3D scanner and used NX Imageware 13 software to collect 48 foot parameters.The relationship between the parameters of the foot was explored by correlation analysis and regression analysis,based on which principal component analysis was performed to extract three principal component factors affecting the foot size:foot length factor,foot width factor and foot thickness factor.Through feature selection,three feature indexes that affect the foot morphology were extracted:foot length,foot width and foot arch height.Next,with the use of the proportional index,the foot width index(the ratio of foot width to foot length)and the arch height index(the ratio of tarsal height to the length of the first metatarsophalangeal joint)were used as foot shape classification criteria,and the double K-means clustering method was used to classify the foot shape of young women into nine categories from the three dimensions of length,width and height.Furthermore,the study compared the national standard of the foot classification.Finally,the experimental results were tested for independence and coverage to verify the rationality of classifying foot types by foot width index and arch height index.We discovered that the metatarsal circumference length of modern young women is smaller than the metatarsal circumference length established by the national standard.By analyzing the correlation between the metatarsal circumference length and the foot length and the height of the first metatarsophalangeal joint,it was found that the circumference parameter involved the width parameter and the height parameter.For this reason,the influence of the multidimensional overlap of the metatarsal circumference length on the foot type classification was considered when the foot type classification criteria were determined.The results show that the foot type of young women in Zhejiang province can be divided into nine categories:A1(narrow flat type),A2(narrow intermediate type),A3(narrow high type),B1(intermediate flat type),B2(intermediate type),B3(intermediate high type),C1(wide flat type),C2(wide intermediate type),and C3(wide high type).By calculating the foot type coverage of young women in Zhejiang province,it was revealed that of the middle foot type(B type)that occupies the most,the intermediate type(B2)has the largest proportion.Specifically,shoe size 235 mm(B2)has the largest proportion and can be used as the sample shoe size for the production.Foot measurement and foot type classification of young female feet in Zhejiang province can provide morphological data for the manufacture of foot products and digital modeling,improve the fit,comfort and functionality of female footwear products while have significant theoretical guidance and practical significance for disciplines such as forensic medicine.