DISCUSSION OF PROTO TYPE PATTERN DEVELOPMENT METHODS FOR
WOMEN’S ACTIVE WEAR TROUSER
V. Nithyaprakash
Department of Textile Technology, Bannari Amman institute of Technology.
ABSTRACT:
The major factors influencing the pattern development process are namely: pattern drafting technique,
garment design and fabric drape. The purpose of this article is to compare the different methods of pattern
drafting techniques, different methods of pattern development process and approach and infer the better
option suitable for tomorrow’s industrial practice. The pattern drafting techniques of Pamela stringer and
Winifred Aldrich are compared with reference to the Women’s trouser style meant for climbing and
trekking designed and developed by Brand Patagonia. Measurements of the Patagonia’s style shown in
the picture below are used for pattern construction. Subsequently we also discuss the different types of
processes available for pattern generation namely: the traditional method of 2D pattern development and
2D pattern generation based on a 3D surface flattening method. In order to choose the better option
among these, we discuss the elements of garment design which influence the degree of freedom of
movement in active wear category.
INTRODUCTION:
The first pattern is created or drafted by interpreting the outline of the garment illustration / silhouette.
The garment illustration / silhouette denotes the posture and fit of the garment intended by the designer.
The first pattern called as basic block in pattern making parlance could be either developed from scratch
or obtained by reworking an already existing sloper which closely resembles the silhouette.
Proto sample is used for comparing the garment silhouette and fit against the illustrated sketch. Thus the
whole exercise is centered on verifying the actual garment posture and its functionality obtainable with
the selected fabric.
Several decisions are drawn based upon the following factors for example; fabric drapability behavior,
element of design ease required for arriving at the pattern plot, the garment fit purpose, body posture and
the cross sectional surface measurements & contour while executing this exercise. If the intended garment
is made from stretch fabric, the fabric stretch factor is also considered in arriving at the pattern plot.
In this article we analyze the role of pattern drafting techniques and influence of body posture on pattern
development or generation for women’s active wear trousers.
1. PATTERN DEVELOPMENT:
Interpreting the technical sketch or illustrated image of the intended garment design is the key for pattern
development. A glance at the sketch gives the idea of the garment outline form, line, set and balance.
Thus we decide the pattern plot for the illustrated garment sketch. The illustrated image or sketch is
supported by the technical specification which provides information about construction methods,
measurement specification and other functional requirements of the garment.
Setting out on developing the block pattern, let us compare the different pattern construction methods we
have at our disposal. This is an effort to review the pattern construction techniques for women’s Casual
trousers, their advantages and disadvantages.
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This review of different pattern construction techniques is carried out with reference to Women’s trousers
designed for climbing and trekking. These trousers ( Fig:A, Fig:B) sport a low raise, regular fitting at hip
and waist with the leg being straight from thigh.
Fig:A; Shalimar pant Front view
Fig:B; Shalimar pant back view
(Ref: http://www.needlesports.com/Technical-Clothing/Light-Weight/Womens-Solimar-Pant [7])
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1.1 PATTERN CONSTRUCTION TECHNIQUES:
Measurements for trouser block construction:
Table: 1
S.no
Key measurement areas
1.
½ Waist
2.
½ hip ( measured at 9cm from crotch
point; three point measurement )
3.
½ thigh
4.
½ knee
5.
½ bottom
6.
Front raise
7.
Back raise
8.
Inseam
Measurements
39cm
52cm
32cm
22cm
20cm
24cm
37cm
30inches
(Ref: Size L measurements of Style: Shalimar Pants; Category: very light Active wear for walking and
climbing the mountains,http://www.needlesports.com/Technical-Clothing/Light-Weight/Womens-SolimarPan [7] )
1.2 TROUSER PATTERN FOR VERY LIGHT ACTIVE WEAR; SHALIMAR PANTS: BRAND
PATAGONIA BY PAMELA STRINGER METHOD:
(Ref: pattern drafting for dress making by Pamela. C. Stringer [2])
Front
1.
2.
3.
4.
5.
6.
7.
8.
Crotch line: at the centre front extend the line by ¼ of the block width to “B”.
Center front seam: From “B”, scoop to meet the centre front at the seat
line. Keep out from the corner by 2.5cm.
Waistline: from the top of the block at the centre front go down 1cm. to “E”. from here curve up to
the waistline to measure ¼ waist at “D”. if darts or pleats are required, add the extra needed.
Crease line: this can be stitched. Mark halfway along the base of the block and the knee line. Rule a
line through these points up to the waist.
Inside leg seam: At the knee line and at the bottom of the block, rule up inside leg for about 12cm.
above the knee line, then curve to meet the crotch point.
Outside seam (side seam): curve from the side seam waist down through the hip shaping to the seat
line. From here, gradually shape on down past the thigh line to hem at the required width.
Bottom of Leg: Curve up by 0.5cm at the crease line.
Back
Shape in the front pattern on the back bock and alter in the following way. Both patterns may be drafted
on the same block, but would then need to be traced off separately.
1. Crotch-line extension: 2.5cm. beyond the front extension to “A”.
2. Center back seam: fist move the crease line towards the centre by 1.25cm. At the top of this new line,
square up 4cm. to center back point “C”. from “C” rule a line to the point where the crotch-line meets
the center back of the block, point “G”. This is a guideline only. Mark its halfway point “R”. now
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3.
4.
5.
6.
7.
8.
shape in the center back seam from point “C”. follow the guideline to “R”. now shape in the center
back seam from point “C”. follow the guideline to “R”, then curve to meet crotch point “A”. keep
4cm out from the corner.
Waistline: rule in the waistline from “C” to an extension of the top of the block at “F”. it should
measure ¼ of the waist +2.5cm. for a dart.
Dart: rule in a dart approximately 12.5cm. in length, 2.5cm wide and 8cm. in from the center back. It
must be parallel with the center back seam when stitched.
Inside leg: this is shaped to match the front leg but keeping the extra 2.5cm. out for the full length.
Outside seam: starting at the side seam waistline, curve in a smooth line to meet the front shaping just
below the thigh line. From here rule to the hem, matching the front seam line.
Bottom of the leg: curve the line down by 0.5cm. at the crease line.
Check: check the thigh size over the back and front.
Curved yoke:
Draft the pattern and place the waist dart in both back and front on the crease lines instead of their normal
positions. Evenly shape in the yoke at the back panel, making it the depth you prefer.
( e.x. 6cm deep ). We can also have an alternate shaping for the yoke of dimensions 10cm at the Center
back and 6cm at the side seams. For the front pivot the dart to the bottom of the front pocket facing.
Yokes shaping takes the cue from base pattern shape, i.e compliments the base pattern shape.
(Ref: Fig:1; Trouser pattern for Shalimar pant by Pamela Stringer method, Pg:13)
1.3 TROUSER PATTERN FOR VERY LIGHT ACTIVE WEAR; SHALIMAR PANTS: BRAND
PATAGONIA BY WINIFRED ALDRICH METHOD:
(Ref: Metric pattern cutting for Women’s wear by Winifred Aldrich [3])
Front
Rule down a line of length waist to floor measurement.
Rule waist line, hip line, crotch line and knee line cutting across the vertical line.
Rule down a vertical line at 1/12 of the hip measurement plus 1.5 cm from crotch to waist to the right of
the waist to floor line. This line represents the center front line.
Mark ¼ hip measurement at the hip line from center front.
Mark front crotch extension at 1/16 of the hip from center front at the crotch line.
Go in 1cm a t waist line from center front and join crotch extension point running
through center front hip; forming a smooth curve between hip and crotch extension.
Mark ¼ waist with dart allowance.
And follow up with marking ½ bottom and ½ knee measurements. Front bottom and front knee are 2cm
shorter than their respective positions in the back panel pattern.
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Join your side seam and inseam with smooth curves imitating the garment outline.
Back:
Rule down a vertical line at ¼ of the distance between centre front and crease line of front panel. This is
the center back line.
Go in 2cm and go up 2cm at the waist line of your center back. This point serves as the actual center back.
Now mark your back waist width with dart allowance.
Extend front crotch extension outside by half its width and mark it as back crotch extension.
Join center back waist and back crotch extension running through hip line; the portion between crotch
point extension and mid of center back forms a smooth curve.
Mark hip width plus 1.5cm at the hip line from CB for the back block.
Mark knee width and bottom width for the back block.
Join side seam and inseam curves.
Further we cut open a wedge of required width along the hip line and impart the angular shape to the
center back line required for achieving the desired fit. The darts on the front panel are eliminated by
pivoting and transferring them to bottom edge of the front pocket facing. Similarly the back darts are
eliminated by pivoting and transferring them to the bottom edges of the yokes thus forming a curvier
shape.
(Ref: Fig:2; Trouser pattern for Shalimar pant by Winifred Aldrich method, Pg:14)
2. COMPARISON OF PAMELA STRINGER METHOD AND WINIFRED ALDRICH
METHOD:
The method of Pamela stringer emphasis on the creation of a raised and angular center back seam by
moving the crease line towards the center back.
((Ref: Fig:1; Trouser pattern for Shalimar pant by Pamela stringer method, Pg:13)
While in the Winifred Aldrich method we widen the back crotch extension point and create an angular
center back seam by introducing a wedge at the hip line.
(Ref: Fig:2; Trouser pattern for Shalimar pant by Winifred Aldrich method, Pg:14)
Both these efforts are to impart the shape and lift to the trouser back pattern thus improving the fit a the
center back and crotch point. When we look at the soundness of the technique, in Winifred Aldrich
method the angularity impartation is through perceived judgement of shape approximation which causes a
tilt of grain line at the hip line. Where as in Pamela stringer method the back panel upper half shape is redefined to incorporate angularity. Thus Pamela stringer method is more clinically precise as it takes into
account crease line shift which undermines the garment set and balance at the back hip area.
Hence pattern construction technique affects the outcome of the intended garment design.
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3. INFLUENCE OF POSTURE ON PATTERN DEVELOPMENT:
People indulging in Trekking, Skiing, Mountaineering and other outdoor activities have an erect posture.
In other words, the form and build of this category is more closer to the hour glass models / dress forms
we use in our laboratory which also serve as reference. Rather people involved in computer oriented jobs
have forward leaning posture.
(Ref: Pattern cutting for clothing using CAD by M. Stott [4])
Besides garments meant for these outdoor campaigns demand a high degree of freedom of movement
aiding strides, stretching, running and climbing activities.
So there are two major factors influencing action wear comfort namely: body posture and appropriate
garment design. The Silhouette shown in the tech pack will not directly indicate these wearing ease
requirements mentioned above.
However they are implied through the description of the garment and its functional requirements. Further
the silhouette speaks about the contouring of the garment and its set on the body parts. This is the most
important piece of information in pattern development, as it influences the shaping of the pattern at
respective areas when the pattern is getting developed. This interpretation by the designer / developer is
the key in producing the intended look.
Speaking about assigning the garment ease to the pattern at respective areas: waist, hip, crotch, thigh,
knee and bottom, information about the garment stress point and direction of stretch is important. This
garment ease caters to the room and comfort required for an active wear which gives high degree of
freedom of movement to the limbs without any undue pressure on the skin and joints. During walking the
garment is stressed at the hamstring area to crotch region at the back and knees. While climbing the
garment is stressed at the knee cap and front thigh. Because of the stress developed at theses region the
garment is stretched / pulled along at various points like back raise, front knee cap and front thigh. While
at crouching positions the garment is stressed at crotch point, back raise and yoke region. This amount of
garment stress is further added on by the unique personal gait of the wearer which is an outcome of
his/her body shape and biometrics.
Based upon this interpreted information on the ease requirements, it is added at hip, thigh, knee and
bottom correspondingly without disturbing the garment fit and design comfort. The intention is to
minimize the fatigue created by the garment design while performing these activities.
Hence shaping and contouring principles play a vital role in developing the 2D pattern for active wear
with adequate ease and in defined shape. The answer to how much ease is adequate relies upon testing the
garment performance for these activities. At the development stage we decide the ease requirement on the
basis of the available performance data of different fits in similar garments. After arriving at the adequate
ease, it is incorporated in the measurement specification of the product in addition to the body
measurements.
This approach is essentially an intuitive visual analysis of the body with major assumptions made about
their relationship to the pattern shape. This is the traditional method of pattern development.
4. PATTERN GENERATION USING SURFACE FLATTENING TECHNIQUE FROM 3D
MODEL DATA:
Digital pattern development process from a 3D model through surface flattening is widely used in
Avionic industry, ship building industry and shoe industry. These industries make use of Engineering and
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construction materials whose behaviour are determined by the laws of Modulus and engineering
properties. In Apparels the fabric material property determining the behaviour corresponds to drape,
bending rigidity, elongation, fabric handle and fabric fall. The objective is to identify an alternate method
using scientific principles which is practically adaptable for apparel industry.
4.1 INITIAL STAGES OF DIGITAL PATTERN DEVELOPMENT FROM 3D FORMS:
(Ref: Clothing appearance and fit: Science and technology by J. Fan, W. Yu and L. Hunter [5])
Hinds et al. [6] demonstrated an approach to derive garment pattern pieces from the designed 3D models
at a CAD station. An offset surface with respect to the underlying body form which represents a piece of a
garment was created. A grid of points was necessary for pattern development for this surface. Primary and
secondary spines were first defined. Using these spines and starting out from the origin, a grid on the 3D
surface could be formed. A Newton-Raphson algorithm was used to iterate the intersection of an
approximately equal-sided mesh to the complete surface of the garment. The mesh grid was trimmed later
for the garment pattern. The small darts on the pattern were grouped together to form a single dart at a
specific location.
Fig: 3, Garment piece with a superimposed equimesh grid.
(Ref: Reprinted from Computer-Aided Design, 23, Hinds et al., `Pattern development for 3D surfaces',
583^592, Copyright (1991), with permission from Elsevier [6])
7
Fig: 4, flattened mesh in 2D form
(Ref: Preprinted from Computer- aided Design, 23. Hinds et al., ‘Pattern development for 3D surfaces’,
583-592, copyright (1991 ), with permission from Elsevier [6])
An alternative to the Newton-rapshon algorithm is the radial mesh development; shown in the picture
above. Hinds et al concluded that the dev eloped methods were based on the simple concept of modeling
a doubly curved surface as an assembly of triangular platelets. Groups of such platelets can be flattened
onto the plane to obtain the overall pattern, which reflects the type of curvature on the original 3D
surface.
Fig: 5,The overlaps eliminated by the spreading out of strands.
(Ref: Preprinted from Computer- aided Design, 23. Hinds et al., ‘Pattern development for 3D surfaces’,
583-592, copyright (1991 ), with permission from Elsevier[6])
4.2 DEVELOPMENT OF 2D PROTO PATTERN FROM 3D MODEL USING SURAFCE
FLATTENNING METHOD:
(Ref: Development of a Prototype Pattern Based on the 3D Surface Flattening Method for MTM Garment
Production by Yunchu Yang, Fengyuan Zou, Zhong Li, Xiaofen Ji, Minzhi Chen in FIBRES & TEXTILES
in Eastern Europe 2011, Vol. 19, No. 5 [1])
8
In this technique, a 3D model of a basic bodice garment (only half) is created based on 3D body scanning
data using NURBS surface modeling technology. Each cross-section of the scan data is preprocessed by
three methods namely re-sampling, symmetrizing and calculating the convex hull. The steps involved are
1. Sorting of the data points in order to fit the needs of B-spline interpolation.
2. Fitting the horizontal B-spline curve along the cross-section points and calculate the center point O of
the bounding rectangle of the curve.
3. Re-sampling each cross-section at a uniform angle centered on point O and reorder the sample
sequence .
Fig: 6, Pre-processing of each cross sectional data
( Ref: Development of a Prototype Pattern Based on the 3D Surface Flattening Method for MTM
Garment Production by Yunchu Yang, Fengyuan Zou, Zhong Li, Xiaofen Ji, Minzhi Chen in FIBRES &
TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 [1])
4. Symmetrizing the points with the y axis as the symmetry axis to ensure ρ1 = ρ2, as well as to get a
symmetric torso model for the 3D garment CAD system.
5. Then step 1 and step 2 are repeated to get new samples and a center point of the new cross-section
again because the center point O is changed after carrying out step 3.
6. Now the convex hull of each cross-section point is calculated to create a dress like 3D body model.
The convex hull method is used to mimic the physical tape-measurement of the mannequin for the
purpose of girth generation as well as to simplify the body surface complicacy.
What is NURBS 3D modeling technology?
NURBS model is a polygonal model that has surfaces wrapped over it. A Polygonal model is a model of
an object that is created by building triangles from the points in a point cloud; a faceted model of an
object.
(Ref: http://www.dirdim.com/serv_digitalmodeling.htm[8])
What is convex hull?
Convex hull represents a polygon formed by line segments connecting each pair of points in a finite set.
(Ref: en.wikipedia.org/wiki/Convex_hull [9])
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Triangulation technique is used for mesh creation. Then the mesh created is flattened into 2D surface
using Energy model. The energy model assumes the edges of the surface mesh as an elastic strut taking
into account the material properties. The corresponding feature points and lines are defined on the 3D
model in advance through calculating the intersection curves of the body surface and the local planes.
The triangulation process makes use of two techniques: unconstrained triangle flattening and constrained
triangle flattening.
In unconstrained flattening, the edges on the mesh flat pattern have the same length as that of the edges on
the 3-D triangulated surface, and thus no distortions occur, with the strain energy being equal to zero.
It does not take into account the planar position, (i.e: anterior or posterior position of the point that is
getting developed) of the developed point which is not the case with 3D forms which is essential for
computing the shape of the corresponding area.
Thus we use constrained triangulation technique which uses this strain energy and constitutes the fact that
the length of the edge will change in flattening process from 3D to 2 D.
Fig: 7, Constrained triangle mesh flattening;
(Ref: Development of a Prototype Pattern Based on the 3D Surface Flattening Method for MTM Garment
Production Yunchu Yang, Fengyuan Zou, Zhong Li, Xiaofen Ji, Minzhi Chen in FIBRES & TEXTILES in
Eastern Europe 2011, Vol. 19, No. 5 [1] )
5. PRACTICAL SIGNIFICANCE:
This article shall be useful for professionals working with Active Bottom wear clothing where they use
different types of fabric weights ranging from 3 Oz to 11 Oz in both stretch and non-stretch category.
6. CONCLUSION:
Each pattern construction method speaks about ways of positioning the waist line, maintaining the
garment side seam line, inseam line and crotch point definition which are keys in developing a balanced
pattern. However the distinguishing feature is the definition of center back angularity and lift which
determines the shape of the garment and its set. Both the methods discuss about different ways of
achieving the angularity.
The method of Pamela stringer emphasis on the creation of an raised and angular center back seam by
moving the crease line towards the center back.
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While in the Winifred Aldrich method we widen the back crotch extension point and create an angular
center back seam by introducing a wedge at the hip line.
The fit trail is the ultimate judge of the garment fit and set, however we have the liberty to choose the
better construction method by understanding the basic principles, as it makes your job easier in hitting the
fit in fewer trials.
Similarly there are two ways of determining the garment’s 2D dimensions one is a traditional method and
the other is by graphical Somatometry. Traditional method relies on the designer’s / developer’s skills in
hitting the silhouette with right measurement and fit. It reflects a method of deciding the basic pattern plot
based on two dimensional measurements of the human body, but it is difficult to reflect a 3D shape.
However it is most successful method of 2D pattern system in the industry.
Using graphical Somatometry we can develop a 3D from from a set of points obtained by scanning a 3D
model and further we can breakdown it into 2D patterns using surface flattening method. It relies on the
measure of fabric stretch properties in computing the 2D dimensions and shape of the pattern. Hence
Graphical Somatometry and surface flattening technique are superior in more than one way by virtue of
the body shape contouring details it provides to achieve the desired pattern plot. But it develops only the
bodice pattern not the flat pattern. The garment ease requirement’s influence on the action comfort which
makes up the garment design has to be decided manually based on fit trials or on the available fitting data
and knowledge of similar designs.
BIBLIOGRAPHY:
(Journal articles)
1. Development of a Prototype Pattern Based on the 3D Surface Flattening Method for MTM
Garment Production by Yunchu Yang, Fengyuan Zou, Zhong Li, Xiaofen Ji, Minzhi Chen in
FIBRES & TEXTILES in Eastern Europe 2011, Vol. 19, No. 5 [1].
(Books)
2. Pattern drafting for dress making by Pamela. C. Stringer [2].
3. Metric pattern cutting for Women’s wear by Winifred Aldrich [3].
4. Pattern cutting for clothing using CAD by M. Stott [4].
5. Clothing appearance and fit: Science and technology by J. Fan, W. Yu and L. Hunter [5].
6. Reprinted from Computer-Aided Design, 23, Hinds et al., `Pattern development for 3D
surfaces', 583^592, Copyright (1991), with permission from Elsevier [6].
11
(Websites)
7. Http://www.needlesports.com/Technical-Clothing/Light-Weight/Womens-Solimar-Pant [7].
8. Http://www.dirdim.com/serv_digitalmodeling.htm[8].
9. En.wikipedia.org/wiki/Convex_hull [9].
APPENDICES:
S.No
Appendices
Page No
1
Fig: A; Shalimar pant Front view
2
2
Fig: B; Shalimar Pant back view
2
3
Table:1; key measurements for Trouser construction
3
4
Fig:1; Trouser pattern for Shalimar pant by Pamela stringer method
13
5
Fig:2; Trouser pattern for Shalimar pant by Winifred Aldrich method
14
6
Fig:3, Garment piece with a superimposed equimesh grid
7
7
Fig:4, Flattened mesh in 2D form
8
8
Fig:5, The overlaps eliminated by the spreading out of strands
8
9
Fig:6, Pre-processing of each cross sectional data
9
10
Fig:7, Constrained triangle mesh flattening
10
12
13
14
15