Page 152 - Anthropometry, Apparel Sizing and Design

Full body 3-D scanners 147

be set up in a truck and moved from one site to another. This generation of scanners
had multiple sensors placed around the body that allowed the subject being scanned to
remain stationary instead of rotating on a platform. They were all similar in that they
consisted of a light source, sensing devices, software to assemble the scan from the
data from the sensing devices, and software to extract information (generally simple
linear measurements) from the assembled scan.
Basic 3-D body scan data from these scanners and from 3-D scanners in general are
expressed in an XYZ coordinate space. These scanners captured and plotted points
from the surface of the body, generally in a grid density of 2mm 2mm resulting
2
in about 27 points per cm or about 300,000 points in a scan of an average-sized per-
son. The points could be triangulated and surfaced to create a statue-like rotatable
image. The systems that had cameras to capture color and texture information gener-
ally “wrapped” this information as a separate layer onto the 3-D model.
The volume of the scanning area differed among scan companies but was generally
in the range of 2.1m (height) 1.2m (depth) 1m (width) and accommodated a
standing or seated person. The available scanners differed greatly in the mode of rep-
resentation of the scan data on the computer screen, from a simple point cloud to a
model with triangulated and surfaced points highlighted with simulated lighting
and providing different choices in perspective rules for viewing the model (see
Fig. 6.2). The displays also varied in how much postprocessing was applied to the scan
data, beyond simply assembling or merging the different camera views. Any scanner
creates redundant points, either throughout the surface of the scan (white light scans)
or in the overlapping camera views (laser light scans) (see Fig. 6.3). The task of the
software developer who generates the program to assemble and justify these redun-
dant data points is to create a digital model that will have the same measurements
and shape of the complex, organic body. Reducing the scan to essential points will
also reduce the size of the file, without losing needed information (see Fig. 6.4). This
process can also improve scan visualization.
Generally, these early scanners were marketed as a sophisticated measuring device
that could extract a large number of linear measurements and some angle measure-
ments automatically from the scan. These measurements (which were based on data
taken by manual measuring tools such as tape measures, anthropometers, goniome-
ters, and calipers), and not the actual 3-D scan data themselves, were often the focus
of the data display. As is frequently the case with new technologies, many researchers
did not have a good concept of how to use the actual 3-D scan itself, as 3-D data were
unfamiliar.
The measurements that were generated from the scans varied, with some modeled
on standard anthropometric practice and some modeled on the measurements made by
tailors and the apparel industry. Scanner companies also developed the capability to
scan and derive measurements from subjects in seated positions to generate data for
the automotive and airline industries. Multiple studies were conducted to verify the
reliability and validity of the measurements of the different scanners, comparing auto-
matically derived scan measurements with manually taken measurements of the same
subjects (Bradtmiller and Gross, 1999; Paquette et al., 2000; Mckinnon and Istook,
2001; Choi and Ashdown, 2010). Studies were also conducted on issues relating to