Measured Dimensions vs. Scanned Dimensions: The Case for Both

Apr 4th, 2018

In much of our work at Anthrotech, we complete assignments for clients that require us to obtain measurements of the human body in various positions. Sometimes, it makes sense to obtain dimensions using a scanner, and sometimes it makes sense to use a measuring tape or calipers. Today, we discuss what parameters help us determine which option is best for a particular project.

The case for scanned dimensions

Three-dimensional (3D) whole body, head, hand, foot and other scanners provide an opportunity for collecting large quantities of data points. This scanning technology has opened up new possibilities due to the ability to rapidly collect human measurement data, as well as to collect previously unavailable shape data.

There are simply some critical data points that are difficult to gather with a tape or calipers. For example, when measuring for certain clothing – like pants – it is useful to know the hip circumference and the waist circumference. With a tape, you are able to measure the circumference of each of these individually. However, with a scan, both of these measurements can be extracted simultaneously, and more usefully in this case, you capture the distance between them as well as the fore-aft relationship of the hip and the waist. More significantly, scans can also provide information about the shape and contour of the body that is difficult or impossible to track with a tape.

As another example, envision the contours around the nose and mouth that need to be covered by a respirator. Knowing the shape of that area of the face allows respirator designers to make a mask that fits much more closely than a mask created with linear dimensions alone.  

The case for measured dimensions

There are other cases when using a traditional measuring tape is best for a variety of reasons. Clothing is traditionally measured with a tape, for example. If you’re measuring to fit a hat or helmet, you would want to measure dimensions on the head that include areas of the hair that would be compressed when the product is worn. You can manually compress the hair using a tape. A scan would capture the head and the hair in its natural, uncompressed position, and that wouldn’t be as useful.

Measuring a person in street clothing is typically easier with a tape because you can get reasonably close to the body under the clothing. Using a scanner, you would have the surface of the clothing accounted for, but no information about where the body was beneath the clothing. Depending on the type of clothing involved, such a scan might or might not provide useful information about the body beneath.

Additional considerations

At first, you might think measurements with a tape and calipers are more time-consuming, so you assume scans are typically faster to complete. But that’s not always the case. A scan will not produce actual measurements; those need to be extracted from the scan. If the measurement extraction is automatic – which may be less reliable – the process is typically fairly quick. But, if you’re looking for high-accuracy measurements from a scan, a skilled technician will place landmarks on the scan in order to extract measurements, and that can be quite time-consuming, depending on the number of landmarks. In the end, time is likely not the most important factor when determining whether to use scanned or traditional measurements.

Budget may not be a huge factor either. The most expensive part of large surveys is typically getting the team in place and recruiting the correct participants; there often isn’t a large additional cost to incorporate both scans and traditional measurements into a project.

Clearly, reducing any possible error is important in whichever type of data you collect. In the case of traditional measurements, error is reduced by training and practice. The same is true of the person placing landmarks on the scans; he or she should be well-trained and have lots of practice before starting the landmarking process. The kinds of errors differ between the two methods, but training and practice are key to both. In a future blog, we’ll talk about how to reduce errors in anthropometric data collection. Because of the value of each data collection method, most projects will make use of a combination of both traditional anthropometric measurements and 3D scanning. At Anthrotech, we consider the benefits of both approaches and customize a solution that makes the most sense for our clients’ unique goals.  

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