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3D virtual prototyping in garments

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3D virtual prototyping of clothing products
Chapter · September 2012
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3D VIRTUAL PROTOTYPING OF CLOTHING
PRODUCTS
Zoran Stjepanovič1, Tanja Pilar2, Andreja Rudolf1, Simona Jevšnik3
1
University of Maribor, Faculty of Mechanical Engineering, Department of
Textile Materials and Design, Slovenia
2
ORTUM d.o.o., Ljubljana, Slovenia
3
Academy of Design, Ljubljana, Slovenia
Abstract
Producers of fashion and special garments are nowadays oriented towards the
reduction of development cost and prototype development time. 3D virtual
prototyping, which has been recently introduced to clothing industry, become a
topic of increasing interest of both computer graphics and clothing industry.
Based on the results of many recent studies, we can claim that 3D virtual
garment prototyping is a promising technique, which will due to its potential
considerably replace conventional methods of clothing prototypes’ development.
These technologies are especially important when a garment prototype should be
developed for special purposes such as competitive sports apparel, protective or
special clothing.
Keywords: clothing, 3D virtual prototyping, women’s apparel, sports clothing
1. Introduction
The aim of this research was to study and to enable a process of 3D virtual
prototyping of fashion clothing as well as competitive sports apparel and to
analyse its efficiency compared to conventional technologies. For this purpose
we obtained the 3D body scans of some representative persons. The body
models required a substantial reconstruction, after which we were able to import
the body models into commercial CAD/PDS package. Furthermore, we prepared
virtual parametric body models, which were also used for 3D virtual prototyping
and virtual try-on. Special attention was given to correct data for computational
material model since this was important for a realistic virtual garment fit
visualisation. Finally, comparison of virtual and real garments’ fit using different
body models was made.
Based on the results it can be concluded that material properties must be
considered and detailed knowledge of textile parameters for each part of the
garment is vital for a successful virtual clothing prototyping. Furthermore, it has
been confirmed that parametric body model is not sufficient to achieve adequate
body shape of a particular person resulting in a suitable fit of clothing product.
Indubitably, virtual 3D prototyping has a substantial potential for clothing
prototype designers and clothing manufacturers.
2. Theoretical part
The application of computer aided design (CAD) intended for garments
development and their virtual prototyping has become an obvious trend in many
of industries recently. Nowadays, the virtual prototyping allows us an accurate
and rapid development of garments, as well as an adaptable and quickly
changeable garments [1, 2, 3, 4]. Virtual garment simulation is the result of a
large combination of techniques that have also dramatically evolved during the
last decade. Unlike the mechanical models used for existing mechanical
engineering for simulating deformable structures, a lot of new challenges arise
from highly versatile nature of cloth. The central pillar of garment simulation
presents the efficient mechanical simulation model, which can accurately
reproduce the specific mechanical properties of the cloth. The cloth is by nature
highly deformable, therefore the mechanical representation should be accurate
enough to deal with the nonlinearities and large deformations occurring at any
place in the cloth, such as folds and wrinkles. Moreover, the garment cloth
interacts strongly with the body that wears it [5, 6].
Three-dimensional body model is critical for the virtual try-on system and has a
strong impact on complexity and effect of a garment simulation. Therefore, the
study of 3D body modelling has a great potential in both research and
application. It is well know that commonly used methods include non-uniform
rational basis spline (NURBS), manual modelling and 3D body scanning. 3D
body scanning has become prevalent since 3D scanning technology is introduced
into garment industry. It provides a realistic 3D body model on the basis of raw
body scan data.
2.1 3D virtual prototyping of garments
The purpose of prototyping is to build a virtual model that instead of developing
a real product. Virtual prototypes can then be presented to the client for
evaluation and confirmation. The final model/product can then be quickly and
easily modified and produced [7]. In recent years, a strong development of
computer technology enabled substantial changes in the way of development of
new clothes and a shift from the conventional to virtual prototyping, figure 1 [8].
Figure 1: Representation of a 3D virtual prototyping process
In this work we are describing the 3D virtual prototyping of garments using two
groups of clothing products: women’s fashion clothing and competitive sports
apparel. The main aim of this research is to introduce an accurate and fast
process for development of fashionable and sports garments. Above all, the
development of a specific sportswear for professional purposes, such as
competitive ski-jumper suit, should be based on virtual prototyping and realistic
simulation of garment behaviour in virtual environment on real 3D body model,
gained by scanning technology. This allows us an effective individual treatment
of a sportsman and effective development of a competitive jumpsuit taking into
account the changeable demands. Because of the safety reasons the FIS
requirements for jumpsuit construction change annually or even more often,
which requires a rapid development of prototypes and final sports clothing.
2.2 Acquiring the 3D body scans
3D body scanning of selected persons (women and professional ski-jumpers)
was performed using the 3D body scanner Vitus Smart at the Textile
Technology Faculty, University of Zagreb, Croatia. The scanner consists of 8
cameras that provide 500 000 to 600 000 points (point cloud). After that, the
body measures were taken using the programme package ScanWorx V 2.7.2.
2.3 Reconstruction of 3D body scan models
For the purpose of the research we firstly used the parametric 3D body model of
selected female and ski-jumpers, determined with body measures obtained by
the scanner. The parametric models were defined using the following measures:
body high, chest circumference, waist circumference, neck circumference,
length crotch-floor, high thigh circumference, knee circumference, shoulders
width, shoulder slope, upper arm circumference and arm length. A great
deviation between the parametric 3D body models, and scanned 3D body models
of both selected female and ski-jumper is obvious, figures 2 and 3 [8, 9, 10, 11].
Therefore, we decided to use primarily the scanned 3D body models for
simulation of final garment prototypes.
The process of generation of scanned 3D body models involved the body
reconstruction. Namely, 3D scanner cannot produce sufficient scan data, which
results in defected body models. For this reason the reconstruction of the
scanned 3D body models of selected female and ski-jumper was performed by
using the programs Atos, Blender, Rhino 4, Netfabb and MeshLab [8, 11, 12, 13,
14, 15, 16].
(a)
(b)
(c)
Figure 2: Parametric 3D body model (a), scanned 3D body model showing defects (b)
and reconstructed 3D body model (c) of a selected female
(a)
(b)
(c)
Figure 3: Parametric 3D body model (a), raw 3D body model showing defects (b) and
reconstructed 3D body model (c) of a ski-jumper
3. Experimental part
The study discusses the development of the prototypes of two types of
fashionable women’s clothes: skirts and jackets, as well as ski-jumper’s suit with
a purpose to identify differences between the conventional and virtual garment
prototyping process. Real and virtual clothes were compared on the basis of the
criteria for assessing the fit of clothing to different body models (real body,
parametric and scanned body model).
3.1 Materials and models of garments used in a study
3.1.1
Women's fashionable garments
Models of women's skirts and jackets were made of fabrics suitable for upper
garments composed of different natural fibres (cotton, linen) and mixtures
(linen/PA); some fabric contained 2-3 % elastic yarns. Fusing was performed in
all models using the same type of adhesive interlinings and Mayer fusing
machine. Altogether, 3 models of skirts and 3 models of jackets were developed,
figures 4 and 5, each of them using two different fabrics [8].
(a)
(b)
(c)
Figure 4: Skirt models Nika (a), Sandy (b) and Verena (c)
(a)
(b)
(c)
Figure 5: Jacket models Nika (a), Lida (b) and Mia (c)
3.1.2
Ski-jumper’s suit
For the prototype of a ski-jumper suit we planned a five-layer laminated fabric
consisting of [17]:
- first layer: outer fabric,
- second layer: foam,
- third layer: elastic membrane,
- fourth layer: foam and
- fifth layer: lining fabric.
The components are laminated together by either a hot-melt process or flame
lamination. The outer fabric and lining fabric is a bi-elastic warp-knited fabric
(Charmeuse), which is produced on a 2-thread system warp knitting machine.
To obtain the realistic virtual prototype of the ski-jumpsuit the measurements of
the mechanical properties of the laminated fabric were done by using the FAST
measuring system [18]. The measuring results of the mechanical properties of
the laminated fabric were converted by using the Fabric Converter programme
and simulation of the laminate draping and jumpsuit fitting was carried out by
OptiTex programme, table 1.
Table 1: Mechanical properties of the laminated fabric measured by FAST
measuring system and converted properties for jumpsuit simulation using
OptiTex programme
PROPERTIES
Extension at load of 98,1
Nm-1 / E 100
MEASURED VALUE
UNIT
COURSE D.
WALE D.
OptiTex parameters
UNIT
-2
COURSE D. WALE D.
%
9.6
10.9
gcm
Bending rigidity / B
Nm
44.8
54.5
dyn*cm
4965
Shear rigidity / G
Nm-1
199
dyn*cm
1990
Surface thickness / ST
mm
0.035
cm
0.0035
Mass per unit area / W
gm-2
601
-2
gm
400.641
352.858
601
4. Results and discussion
Corresponding properties of textile fabrics have to be measured and used for
virtual simulation of garments. In our study we have used the OptiTex CAD
system, which allows also the selection of database values, which describe
particular fabric types/properties. In our study we used the fabric properties
(tensile, shear, bending and surface properties) measured by KES-FB and FAST
measuring systems. Conversion of measurements has been carried out by a
Fabric Converter programme [19].
4.1 Evaluation of a garment fit
4.1.1
Women's fashionable garments
Assessment of a fit of clothing to the body of all models was performed by:
(a) assessing the fit of 3D virtual garment prototypes on parametrical body
according to the parameters of the material and
(b) assessing the fit of 3D virtual garment prototypes on real person, parametric
and scanned body models.
For this purpose, we developed a procedure for evaluating the fit of garment
prototypes to the body for all skirts and jackets. Specific garments areas were
defined, figure 6, after which we observed/evaluated the front, side and rear
views.
Figure 6: Three (coloured) evaluation areas of skirts and five evaluation areas of jackets
(front and back views)
The evaluation procedure is suitable for both real and virtual models and
includes the following steps:
 The clothing item is chosen.
 Evaluation area is chosen.
 Assesment of a garment fit to the body using the following criteria
grades: 1 (good); 0 (satisfactory) and -1 (inappropriate).
The evaluation of a fit of 3D virtual prototypes of fashionable women’s
garments to the real, parametric and scanned body models, figure 7, gave very
interesting results, therefore we are presenting a part of them in this publication.
Using the above described areas and criteria we firstly carried out an expert
evaluation. After that, we also performed a non-expert evaluation using specially
prepared questionaries using a group of 16 persons having a limited knowledge
in a discussed area. The results of expert and non-expert evaluation did not differ
significantly.
Assessment of fit of prototypes of women's real and 3D virtual garment
prototypes on real body, scanned and parametrical body models are collected in
table 2 (skirts) and table 3 (jackets). Altogether we evaluated 9 areas related to
three views of skirts and 14 areas related to three views of jackets.
(a)
(b)
(c)
(a)
(b)
(c)
Figure 7: Fitting results for skirts and jackets on (a) real body, (b) scanned body model,
(c) parametric body model (front, side and back views)
Table 2: Assessment of fit of prototypes of skirts on different body models
Model
Skirt NIKA-1Č
Skirt NIKA-2Č
Skirt SANDY-1Z
Skirt SANDY-3Z
Skirt VERENA-3M
Skirt VERENA-4B
Real
prototype
1
6
4
5
6
8
5
Grade
0
3
4
4
3
1
2
-1
1
2
Virtual
prototype on a
scanned body
model
Grade
1
0
-1
2
6
1
4
4
1
3
6
1
5
3
5
4
6
2
1
Virtual
prototype on a
parametric body
model
Grade
1
0
-1
7
2
4
5
6
3
6
3
4
4
1
5
4
-
Table 2: Assessment of fit of prototypes of jackets on different body models
Model
Jacket NIKA-1Z
Jacket NIKA-1Č
Jacket LIDA-2M
Jacket LIDA-2Č
Jacket MIA-4B
Jacket MIA-4M
4.1.2
Real
prototype
1
6
7
6
4
5
5
Grade
0
4
3
5
7
6
4
-1
4
4
3
3
3
5
Virtual
prototype on a
scanned body
model
Grade
1
0
-1
5
6
3
7
5
2
7
7
7
7
8
5
1
8
5
1
Virtual
prototype on a
parametric body
model
Grade
1
0
-1
6
7
1
7
5
2
13
1
13
1
11
2
1
12
2
-
Ski-jumper suit
For the 3D virtual simulation of the competitive prototype of the ski jumper suit
it was necessary to define the jumpsuit patterns by:
 type and position of the individual pattern regarding the virtual mannequin
(e.g. front part, back part, sleeves etc.),
 measured mechanical properties of the laminated fabric for all jumpsuit
patterns and
 seam lines for stitching the patterns on the (a) parametric 3D body model
and (b) scanned 3D model of ski-jumper, Figure 8.
(a)
(b)
Figure 8: Positioning of the jumpsuit patterns on (a) parametric and (b) scanned 3D body
model, and appointed seams for stitching
Furthermore, the comparison of the ski jumper suit between the real prototype,
simulated jumpsuit prototype on the parametric 3D body model and simulated
jumpsuit prototype on scanned 3D body model of the ski jumper was performed.
Figure 9 represents 3D virtual prototypes on parametric and scanned body
models.
Figure 8: Virtual 3D prototypes of a ski-jumper suit on (a) parametric body model and
on (b) scanned body model
The computer simulation of the ski jumpsuit prototype was made using the
parametric 3D body model and reconstructed scanned 3D body model. In order
to assure appropriate simulation of the jumpsuit different positioning and
adjustment of the patterns regarding the parametric 3D body model and scanned
3D body model should be performed. The reason for this are different postures
of the 3D body models. With the aim to make a proper comparison of virtual and
real jumpsuit, we also produced a real prototype. When estimating the fitting of
the jumpsuit the evaluation of the neck line, shoulder area and armpit front and
back, as well as form of the sleeves, trousers and waist area were carried out.
When analysing the simulated jumpsuits in the waist area, an additional fold in
the area of waist and buttock area appears, while it isn't visible when simulating
the jumpsuit on a parametric 3D body model. The appearance of the bottom part
of the jumpsuit is smooth and suggests the filling of tension and discomfort. On
the other hand the real jumpsuit and simulated jumpsuit on a scanned 3D body
model of the ski jumper expresses non-stretched trousers and assures felling of a
good comfort and requested width in this area. The form and fitting of the
sleeves are very similar on all of prototypes with the exception of the shoulder
and armpit areas, because of the anomalies of the parametric mannequin.
Additional folds on sleeves appear in elbow area. These are visible on real and
simulated jumpsuit on a scanned 3D body model, while they are not visible on a
parametric body model because of the stretched arms.
5. Conclusions
Advanced computer-supported garment simulation techniques already represent
an important tool for textile and garment designers, since they offer numerous
advantages, such as quick and simple introduction of changes while developing
a model in comparison with conventional techniques. The primary advantage of
virtual prototyping is that we can design clothes while directly monitoring its
fitting to the silhouette of a specific person without his or her physical presence.
Thanks to latest developments, this new technology will be widely used in the
near future for implementation in daily tasks. This will have an immense effect
on different modules in the clothing industry with its related branches. It can be
seen as a way to move a very traditional industry to a higher level. Computerbased prototyping has a great potential in modern clothing industry because it
allows rapid development of 3D virtual garment prototypes. In a small number
of process steps we may change patterns, colours, fabric types and other
parameters that influence the appearance and behaviour of clothing products.
This study confirmed the applicability of virtual prototyping for both fashionable
and sports garments. Successful virtual prototyping process requires the use of
reliable fabric parameters measured by at least one of objective fabric evaluation
systems. The results of the study confirmed that effective 3D virtual garment
prototyping requires the application of scanned body models instead of simple
parametric body models. The reason for this is that using today’s technology it is
not possible to prepare satisfactory parametric body models taking into account
the age and specificities/deformities of real bodies. Although virtual prototyping
still cannot fully replace conventional prototyping, it surely is an efficient and
helpful procedure that saves time and money in a modern apparel production.
Acknowledgement
The authors wish to express their thanks to colleagues from the Faculty of
Textile Technology, University of Zagreb, Croatia, for enabling us to carry out
the 3D body scanning, which resulted in the realisation of an important part of
the study, described in this article.
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