Feet measurement
Accurately measuring the size and shape of the foot is a key step in designing and producing a fit. Here we introduce a set of practical foot metric parameters and metrics. A reference baseline is defined first, which passes through the middle of the heel and passes through the middle of the distal end of the second metatarsal (ie, the second toe joint). Defining the forefoot line, which starts from the inside of the distal end of the first metatarsal (ie, the big toe joint), usually the most prominent inside of the big toe joint, and the distal end of the fifth metatarsal (ie, the small toe joint). Outside. Three more sections are defined below.
Heel section: From the end of the heel to the end, the amount along the baseline is 0.3 LB (for the definition of LB, see LB=160 mm, for example, then 0.3 LB=48 mm), where the section perpendicular to the baseline is the heel section.
Instep cross-section: from the end of the heel, the amount along the baseline to 0.7LB, where the cross-section perpendicular to the baseline is the instep cross-section.
Toe cross-section: From the end of the heel to the end, measured along the baseline to 1.25 LB, where the section perpendicular to the baseline is the toe cross-section.
Now define a set of foot metrics:
LB: From the end of the heel to the middle of the foreline parallel to the baseline. The actual measurement can be measured from the end of the heel to the end, parallel to the baseline to the big toe joint and the small toe joint, and then take the average of the two, that is, the sum of the two added and divided by 2.
Foot Full Length (LT): From the end of the heel, measured in parallel to the baseline to the front end of the longest toe.
Forefoot width (Wb): Width measured along the forefoot line.
Forefoot perimeter (Cb): The perimeter measured along the forefoot line.
Foreground line inclination: The angle between the foreline and the reference baseline minus 90 degrees, usually 10-12 degrees.
Hi (Hi): The vertical distance from the highest point in the cross section of the instep to the plane of the sole of the foot.
Instep Width (Wi): The horizontal distance from the outermost point to the innermost point in the cross section of the instep.
Toe Height (Ht): The vertical distance from the highest point in the toe cross section to the plane of the sole of the foot.
Heel width (Wh): Followed by the horizontal distance from the outermost point to the innermost point in the cross section of the point H (0.25 LB) in the section.
Heel width (Whp): The horizontal distance from the outside to the inside of the H point (0.25LB, see figure) in the heel section.
Because the foot is a complex structure, when it is stressed, such as standing and walking, it will produce a large deformation. In order to obtain a measure of the force of the foot, we recommend two measures of posture. Standing position: Two legs stand upright on the plane, and the two legs bear the same force. In this case, each leg bears approximately 50% of its body weight. Sitting position: Sit on a stool with the same height as your knee and place your feet flat on the plane. Take the right foot as an example. Press the elbow of your right hand on the right knee and push your upper body forward and apply pressure to your right knee. In this case, the right foot takes about 25% of body weight. One of our studies showed that the feet from being laid flat on the plane are not forced to withstand 100% of body weight, and their size and shape are significantly changed, and most of them (more than 50%) change occurs before the force is higher than 10% of body weight. . In other words, after the force exceeds 10% of body weight, the size and shape of the foot change relatively small. Also note that because the expansion of the soft tissue can cause changes in the size of the foot, it is advisable to measure the foot again after doing the appropriate amount of physical activity, such as walking for half an hour, to avoid the measurement being too small. In addition, if you plan to wear thick stockings, you should adjust the metric value according to the sock thickness.
Hard to find a shoe
Xiao Wang just looked for a company that he hopes will meet with the company next Monday. As the saying goes, the Buddha depends on gold and people rely on clothing. In order to give a good first impression, a perfect costume is essential. There are many new styles of clothing on the market, but the price is very expensive. Wang Wang is prepared to score the next big capital this time. Zhou did not go out to go shopping. In the rest of the day, other clothing was basically completed, but no pair of matching shoes could be found. I don't know how many pairs I tried. The result was not too tight in the forefoot or too wide in the heel. Xiao Wang could not help but sigh: it is difficult to buy shoes!
Most people have had similar experiences with Xiao Wang. It is difficult to find a pair of matching shoes. Why is this? The simple answer is that the size and shape of each person's foot differ greatly. If two people wear the same size shoes, and the size is usually selected by the total length of the foot, the shape of the two feet may be completely different, such as wide, narrow, V-shaped or U-shaped. In order to reduce costs, shoe factories and shoe stores usually use one width and one size of hoe, and at most add a width to certain sizes, that is, wide shoes. The result is that only a small fraction of the lucky ones have their feet exactly the same as those of the shoemakers and can find the right shoes. Most people can only wear leather shoes that are not fit or do not wear leather shoes. If you are interested in this issue, please take a look at one of our research results.
In this study, 51 right-footed females with no foot disease and deformation were used to generate a three-dimensional computer solid model using a three-dimensional laser scanner. The right foot is subject to 25% weight during scanning, and the actual scanning process takes approximately 9 seconds. We use the self-developed CAD (Computer Aided Design) software to measure the set of metrics described in the "Measurement of Feet" article. For ease of analysis and comparison, all metrics are normalized to the palm length LB. The standardization practice is to divide each metric of each foot by the heel length of the foot, and then multiply the average of the heel length of the right foot of all 51 subjects. Let's look at two metrics that are important for comparison: the width of the forefoot and the width of the heel. Based on these two metrics, the feet can be divided into five categories: (Fig. 1) The forefoot and heel width are the average values ​​of the sample and can be called the ideal foot (the left side of the figure is the foot solid model, the middle and the right (Figure 2) The width of the forefoot and heel are both large and wide; Figure 3. The width of the forefoot and heel are both small and narrow; (Figure 4) The forefoot The width is larger and the heel width is smaller, the V-shaped foot; (Figure 5) The width of the forefoot is small and the heel width is larger, U-shaped. Assuming that each measure of the foot originates from a normal distribution sample, several quantitative metrics are explained here quantitatively.
Forefoot width: The average value is 90.1 millimeters and the mean square error is 5.1 millimeters. If the forefoot width of the shoe is 90.1 millimeters, and the wearer can tolerate the difference of plus or minus 5.1 millimeters, then about 68% of people can fit this forefoot width. According to our experience, the extra width of 5.1 mm in front of the palm is acceptable, but narrowness of 5.1 mm can cause damage to the foot. Shouldn't use a foot instead of a hoe to put the shoe up. So only about 34% of people can fit in this way.
Forefoot perimeter: the average is 225.0, with a mean square error of 12.4, assuming that the difference of up to 12.4 can be tolerated, and only about 34% can fit.
Heel width: average 64.3 mm, mean square deviation 3.8 mm. Assuming that more than 7.6 millimeters of difference can be received, about 68% of the able people are suitable.
To sum up, if we only consider the length of the foot (ie size), the width of the forefoot, the length of the forefoot and the width of the heel, the proportion of adults who can fit a shoe made of a single shape per size does not exceed 34%. Our statistical analysis of these metrics shows that the correlation coefficient between these four metrics is very low. In other words, these four metrics are relatively independent. A pair of ideal shoes must be suitable for all four measurements. If necessary, the measurement of the back of the foot must be taken into consideration. This way, a certain number of well-known shoes can be found to be far less than 34%. Our other study of male feet also yielded basically the same results. So buying a shoe is hard to imagine!
So can custom shoes solve this problem? At present, most of the services required by customers for customized skins are based on the use of standard gimmicks (some of them are made on the standard gimmicks). Although there are many choices in style, they do not solve the fundamental problem of fit. The way to completely solve this problem is to customize the gimmick according to the customer's foot type, and then use this personalized gimmick to customize the shoes. This is the only way for people with foot or deformed feet.