Page 158 - Anthropometry, Apparel Sizing and Design

Full body 3-D scanners 153

the data assembly and smoothing process. White-light scanners can be very sensitive
to color contrasts in the object being scanned. The scanning space must be isolated
from the light from the environment, blocking the view of the person being scanned
from the researcher. This can be a problem when a specific posture is required as the
researcher cannot coach the subject into the desired position easily if the study par-
ticipant is closed in a booth. TC2 is the primary vendor of structured light scanners.
Millimeter wave: Millimeter-wave scanners use nonvisible wavelengths that can
travel through clothing and scan the surface of the body, unlike other scan technologies.
The only scan company marketed to the apparel field using this technology is Intellifit.
These scanners are used primarily for size selection in shopping malls. This technology
is also used in the body scanners developed for security purposes in airports and other
locations. Millimeter-wave scanning can occur in the presence of white light.
Infrared: Infrared scanners also use nonvisible wavelengths, but cannot scan
through clothing. Infrared scanners are relatively recent and can be more affordable
than other scan technologies. Infrared depth sensors are often used along with software
that updates and refines the image continually based on new input, thereby developing
effective handheld scanners. Though scan resolution cannot yet match stationary
scanners, the technology is rapidly developing. Companies marketing infrared scan-
ners include SizeStream and Styku. Most of the more recently developed scanner tech-
nologies use an infrared or near-infrared light source.
Four-dimensional scanning (3-D scans in motion): Full-body 3-D scans are taken with
multiple cameras and LED lights in a stereophotogrammetry process, acquiring the data
very quickly. This allows capture of body movement in 3-D over time. The scanner has a
large footprint and high cost. Just as was the case in early body scanning, there is not yet a
clear understanding of how these data can be best used in the apparel industry, resulting
in great opportunities for researchers to develop new methodologies and data collection
processes. 3dMD is the provider of full-body 4-D scanning capability.

6.4 Scanner issues relating to hardware and the
subject being scanned

6.4.1 Calibration

Most scanners require an initial calibration process to align and coordinate sensors and
periodic calibration to correct any drift or to ensure that the initial setup is being
maintained. This process often makes use of a geometric object of known dimensions
and can be simple or complex. The best designed systems have quick and easy calibration
procedures with clear instructions and directions on what to do if the calibration fails.

6.4.2 Scan time
Most scanners are designed to collect the data for the scan in 3–12s. Scan time is opti-
mized for the amount of time that an unsupported person can stand still without
starting to sway (Daanen et al., 1997b). Scans could be taken with higher resolution