Abstract
Foot dimension information on different user groups is important for footwear design and clinical applications. Foot dimension data collected using different measurement methods presents precision and accuracy problems. This study compared the precision and accuracy of the 3D foot scanning method with conventional foot dimension measurement methods including the digital caliper, ink footprint and digital footprint. Two-way ANOVA was performed to evaluate the sex and method effect on the six measured foot dimensions. In addition, the mean absolute difference values and intra-class correlation coefficients (ICCs) were used for precision and accuracy evaluation. The results were also compared with the ISO 20685 criteria. The sex and the measurement method were found (p<0.05) to be significant on the six foot dimensions. The 3D scanning measurements showed the best precision performance among the four measurement methods. The accuracy results indicated that the 3D scanning measurements had better accuracy performance than the other methods (mean absolute difference was 0.6 to 4.3 mm), except for measuring outside ball of foot length and foot breadth horizontal. The ICCs for all six foot dimension measurements among the four measurement methods were within the 0.61 to 0.98 range. Overall, the 3D foot scanner is recommended for collecting foot anthropometric data because it has relatively higher precision, accuracy and robustness. This finding suggests that when comparing foot anthropometric data among different references, it is important to consider the differences caused by the different measurement methods.Further, this study classifies the foot shapes of Taiwanese using 3D foot scanning data from 2000 males and 1000 females. Nine foot dimensions relative to foot length and absolute measures in the common foot length categories were applied to compare the gender differences. Using foot breadth in % foot length, ball of foot length in % foot length and arch height in % foot length as feature parameters can classify three foot shape types for males and females, respectively. Significant gender differences were found in seven of the nine foot dimensions (mean differences 0.2% to 2.8% foot length). Females had greater ball of foot length than males (0.2% foot length). Males had greater breadth, girth and height dimensions than females, except for toe height. Moreover, ethnic differences in foot shape were also observed. The findings can provide very useful information for building gender specific shoe lasts and designing footwear insoles.