The following are the findings of 20 people who had their back shoulders measured both automatically(using 3D Measure Up Software) and manually. We have also captured measurements for different body parts. The purpose of this study was to examine the precision of 2 different tools for collecting anthropometric data on the shoulder.
The differential value was found to range from -0.09 to 1.6 inches.
Table 2.2: Percentage of accurate measurements across scans of 30 subjects
Cause of variations
- Accuracy of scans:
The discrepancy between the true measurement of what you’re scanning and the results of what you’ve scanned is what’s known as accuracy. The greater the discrepancy, the less accurate it is.
- Fused meshes:
When the subject is scanned in a relaxed posture. The arms get fused with the torso. The fused mesh areas cause problems in the identification of measurement points and body features.
Fig 1.0 Fused Chest Measurement
- Inherent manual measurement differences
It has been acknowledged that manual tape measurement of the circumference is normally smaller than surface measurement due to the tension of the tape
Since the accuracy of 3D Measure Up is tested in real-life scenarios rather than using test rigs or dummies and for most commonly used measurements, the results are dependable. Measurements were extracted manually by experts and by using 3D Measure Up match in more than 96% of the cases. The mismatch is mostly for trickly measurements like the waist. Each one has a little difference in the way the waist is measured and how tight the tape is while measuring.
What do we mean by Repeatability?
We tested 3D Measure Up for repeatability to know how reliable and dependable our system is.
Reliability is defined as the probability that a product will perform its intended function adequately for a specified period of time, or will operate in a defined environment without failure. We conducted reliability for 3D Measure Up software with the help of differences between automatic measurements derived from different scans of the same person. The scans are taken within a fixed period of time.
How did we test?
Scanned 4 people, 5 times within 15 minutes
- Person is standing in relaxed position
- Different body shapes, sizes, and postures
- Wearing Formfit clothing
The results of different scans of a person taken at 15-minute intervals are listed below. The scans appeared to have variations with the allowable tolerance.
The graph below shows the variations in the back shoulder width.
Cause of variations
1. The postures of individuals change slightly from one scan cycle to another. This slight change may result in the measurements being off.
2. Scan time matters as the body changes during the scan and between scans :
- Breathe-in and Breatheout volumes are different: Each scan should be taken in either a breathe-in or breathe-out state.
- Height can change during the whole day: The time difference between the scans should be minimal. (refer: https://jamaicahospital.org/newsletter/are-we-taller-in-the-morning/, https://www.bmbtrj.org/article.asp?issn=2588-9834;year=2017;volume=1;issue=2;spage=113;epage=119;aulast=Vuvor)
- Weight and volume changes based on the food and water intake i.e. is the stomach full or empty?
- Postural changes between two scans: Though the same person stands in the same pose the posture of the body is slightly different. eg. Hands in A pose may be slightly higher or lower. This adds to the variations in the biceps and chest regions.
- Alignment changes center: We have observed that the center of the body shifts slightly across scans.
- Weight distribution due to postural changes can affect the shape and volume of the muscles
- Tension in various muscles – pull knee muscles or contract glutes or chest muscles or fist open closed.
- The variations of the measurements across scans of the same person is within the tolerance limit.
- The repeatability of the measurements depends on the repeatability of the scanned object.
- The repeatability of the scanner depends on the duration between the scan intervals and changes in the body shape.
The information provided in the study will benefit the collection of anthropometric data for the whole body scan by bespoke apparel businesses. This study shows that the results provided by the 3D Measure Up are comparable to those collected using traditional methods and validate 3D Measure Up for use in anthropometric data collection for the whole body to manufacture bespoke wearables.