Body-to-Pattern Relationships in Women’s Trouser Drafting Methods

Abstract

The authors of this study explored (a) body-to-pattern measurement and shape relationships in trouser patterns drafted by two methods; (b) the consistency of these body-to-pattern relationships between methods and between differently shaped bodies within methods; (c) the patternmaking procedures that cause these outcomes; and (d) how these findings impact garment fit, particularly for mass customization. Body-to-pattern measurement and shape relationships were inconsistent between and within methods, making them unsuitable for use in computer-aided custom patternmaking. Most strikingly, pattern crotch shapes were similar within each method, despite the fact that form crotch shapes were different. Patternmaking procedures causing these inconsistencies include (a) use of proportion of noncorresponding body measurements; (b) use of standard, rather than body, measurements; (c) variations in ease as proportions or standard amounts; (d) trueing, blending, and connecting steps; (e) variation between methods of measurements used, in use of proportions or standard measurements, and in steps; and (h) disregard of body shape.

Keywords

patternmaking measurements proportion mass customization anthropometry apparel industry body scanning body shape computer-aided design drafting

The current ready-to-wear (RTW) clothing system is not able to provide well-fitting clothing for all bodies. This problem is related primarily to an RTW system based on an “average” body and a standard grade between sizes. Although efficient for manufacturing, this system is intrinsically incapable of providing garments to fit the infinite size and shape variations in the population. Even bodies with the same measurements may have varying distributions in the front and back, resulting in the need for a differently shaped garment to achieve good fit (Hlaing, Krzywinski, & Roedel, 2013; Petrova & Ashdown, 2008). Automated production of clothing custom-fit to individuals could eliminate the lost sales associated with ill-fitting apparel (Barrie, 2015) and give apparel manufacturers a competitive advantage (Istook, 2002). Bifurcated garments, specifically trousers, are a well-documented source of fit dissatisfaction for women (Feather, Ford, & Herr, 1996; Goldsberry, Shim, & Reich, 1996; LaBat & DeLong, 1990; Schofield, Ashdown, Hethorn, LaBat, & Salusso, 2006). As such, these garments are prime targets for apparel mass customization.

The steps in the apparel mass customization system have been identified as (a) body dimension collection; (b) style and fabric selection; (c) clothing pattern generation; (d) fabric cutting; and (e) sewing, fitting, and final adjustment (Lu, Wang, Chen, & Wu, 2010). Major goals for apparel mass customization systems are speed, reliability, and accuracy. Such systems should provide apparel for individuals quickly, in order to be competitive with RTW garments. Speed, in turn, requires accuracy and reliability. The product should accurately meet the customer’s expectations without requiring multiple iterations or alterations. The system should reliably produce products that meet the expectations of customers with a wide range of body sizes and shapes. Thus, good first fit for the body of the individual consumer is an important goal for any apparel mass customization system.

Three-dimensional (3-D) body scanning contributes to good first fit by quickly and reliably providing a wealth of accurate body information (Bye, LaBat, & DeLong, 2006; Daanen & Ter Haar, 2013). However, computer-aided patternmaking systems hinder the goal of good first fit because such systems cannot accurately and reliably produce the desired fit relationship, in terms of measurement and shape, between the body and the garment (Chen, 2007).

Current apparel mass customization methods require a step when the individual custom garment pattern is test fit on the body and corrected before the final garment can be produced. This step adds undesirable time and expense to the process. An additional purpose of fit testing is to examine the interaction of the fabric with the design (Aldrich, 2013). This step would likely still need to be performed for new garment designs prior to those designs being available as an option within an apparel mass customization system.

To move apparel mass customization forward, it is first necessary to understand how and why current pattern-drafting systems result in the need for drafted patterns to be corrected to fit individuals. The researchers sought to evaluate current practice to inform methods used for automated systems. The purposes for this research were to (a) understand the body-to-pattern relationships produced by current pattern-drafting methods and (b) test whether these produced relationships are consistent for various bodies. Patternmaking systems comprise theoretical principles—often implicit rather than explicit—in the form of statements of body-to-pattern relationships. The researchers sought to expand the apparel mass customization theoretical framework (Lu et al., 2010) to consider the theoretical principles intrinsically comprising the pattern-drafting system used to achieve the patterns. If the results of a patternmaking system are inconsistent, specific processes within these patternmaking systems that cause these inconsistencies must be identified. In so doing, recommendations for a better system may be proposed. Such an improved patternmaking system may allow for quick, accurate, and reliable computer-aided custom garment pattern-drafting and the advancement of apparel mass customization. A pattern development system that consistently provides a known relationship between body and garment would provide a major step forward toward the practical realization of automated apparel mass customization. Specific impacts of different types of systems are discussed in the literature review.

Literature Review

Good Fit: The Relationship Between the Garment and the Body

To achieve good fit, a garment must have an appropriate relationship with the body in both (a) measurements, known as “ease,” and (b) proportions, known as “shape” (Alexander, Pisut, & Ivanescu, 2012; Petrova & Ashdown, 2008). Ease is the difference between the garment measurement and the body measurement (e.g., garment waist to body waist) and is important, as it allows for comfort during body movement (Watkins & Dunne, 2015). Shape is the proportion of measurements to one another (e.g., a comparison of the garment waist-to-hip ratio to the body waist-to-hip ratio). Shape may also be identified as the relationship of the body shape to a garment shape along the edge of a piece (McKinney, Bye, & LaBat, 2012). For example, the shape of the body and garment along the side seam may be visually compared, as in the analysis by Bye, LaBat, McKinney, and Kim (2008).

Pattern Creation Process

Garment measurements are driven largely by pattern measurements. The pattern for each individual garment style typically is created in a sample size and then graded into larger and smaller sizes (Mullet, Moore, & Prevatt Young, 2009). These sample-size patterns for individual garment styles are adaptations of pattern slopers, which are very basic patterns that fit close to the body. Sloper pattern-drafting methods use recorded measurements of the 3-D body to create a two-dimensional (2-D) shape (Gill, 2015). Two pattern-drafting methods, those of Joseph-Armstrong (2010) and Aldrich (2008), are used extensively in teaching in the United States and the United Kingdom, respectively, and are representative of many of the systems used in sloper drafting patterns (Gill & Chadwick, 2009).

Ease is achieved during the sloper pattern-drafting process by adding additional amounts to the body measurements (Gill, 2011; Rosen, 2004). Patternmaking methods use some direct additions of ease amounts to body measurements (e.g., add 0.50″ to front hip arc; Gill, 2015). Pattern-drafting methods do not directly apply body shapes to the pattern shapes. Presumably, there is some relationship of garment shapes to body shapes, due to the use of the body measurements in the sloper drafting process. However, it is possible that these relationships may be changed by the added ease amounts. Body-to-pattern relationships (ease and shape) resulting from patternmaking methods have undergone limited study.

Computer-Aided Patternmaking Systems for Apparel Mass Customization

Four methods of computer-aided custom pattern generation have been identified (“Made-to-measure,” 2011): (a) programing a computer to automatically generate a pattern directly from a set of body measurements using a pattern-drafting method, for example, as described by Tao and Bruniaux (2013) and Petrak and Rogale (2001); (b) creating multiple sets of patterns that will fit a variety of different body proportions with patternmaking and grading processes (e.g., patterns that can be generated for every possible combination of waist and hip measurement); (c) selecting the closest-fitting pattern from a preexisting set of graded patterns and applying automated alterations to custom-fit the pattern; and (d) unwrapping a 3-D representation of a garment to make a 2-D pattern shape. The first three of these methods use a computer to implement a selected pattern-drafting method. Thus, body-to-pattern relationships that are implicit in the drafting system occur in the generated custom pattern.

More recently, scholars have sought to develop patterns directly from the 3-D body, often using body-scanning technology (Huang, Mok, Kwok, & Au, 2012; Sayem, Kennon, & Clarke, 2012). Huang, Mok, Kwok, and Au (2012) created a network of points that replicate the surface at an offset and can be used to create a flat pattern. Such methods may result in a more direct relationship between garment and body; however, the selected offset (or ease) impacts garment fit. Even for such 3-D systems, it is important to know what the appropriate offset (or ease) is to achieve good fit. Fit provided by patterns created directly from 3-D scans (Huang et al., 2012; Sayem et al., 2012) may be improved by incorporating findings about ease relationships as a definitive rule or formula.

Defining Body-to-Pattern Measurement Relationships (Ease)

The ability of computer-aided patternmaking systems to meet the goal of good first fit is dependent on their capability to produce a predictable body-to-pattern measurement relationship (ease). There has been limited study of body-to-pattern measurement relationships produced by pattern-drafting methods. Researchers have quantified ease produced by various patternmaking methods for a single body. Gill and Chadwick (2009) quantified ease amounts in a bodice block created for a US size 10 Alvanon form by five different patternmaking methods. Ease amounts varied from method to method, causing patterns with the same measurement input to differ. Further, some methods had negative ease in some areas whereas others had positive ease. Gill (2011), who quantified ease amounts in a variety of garment blocks using three patternmaking methods, found that ease amounts were not consistent among methods. McKinney, Bye, and LaBat (2012) discussed ranges of ease amounts added to body measurements in creating the crotch extension in several pant pattern-drafting methods; however, the formulas used and their impact on the final pattern were not analyzed. Researchers have not quantified and compared ease produced by a patternmaking method for multiple bodies. Doing so would identify not only the ease caused by these methods but also the consistency or reliability of the produced body-to-pattern relationship for multiple bodies—a key goal for apparel mass customization. Furthermore, the procedures of the pattern-drafting methods that cause these relationships have not been identified. Doing so may lead to understanding why pattern correction is required to fit individual bodies and may allow computer-aided custom patternmaking to move forward.

Defining Body-to-Pattern Proportion Relationships (Shape)

There is variety in human body hip shapes. Song and Ashdown (2012) observed three main front-to-back hip shapes. Hlaing, Krzywinski, and Roedel’s (2013) work indicated different front-to-back hip depths within the same hip sizes. Current patternmaking methods do not directly incorporate body shape. Even Computer Aided Design (CAD) patternmaking systems that extract body measurements from a 3-D scan do not create pattern curves for the crotch in relationship to the body curves (Sayem et al., 2012; Tao & Bruniaux, 2013). Understanding the body-to-pattern shape relationships that result from following the patternmaking methods may inform improvements in apparel mass customization systems. McKinney et al. (2012) and Lin (2014) studied pant crotch shapes that provided good fit for females and found that pattern shapes varied with body shapes. However, these researchers used pants that were custom-fit to the participants, so the effects of the pattern-drafting methods were not evaluated. Song and Ashdown (2012) classified three shapes of the waist-to-hip region used to group potential relationships between the body and pattern. They suggested pattern changes for the different body configurations that require changes to the crotch extension (among other measurements) to create suitable pattern shapes for their population, indicating the need for attention to body shape in apparel mass customization systems. Body-to-pattern shape relationships created by various pattern block drafting methods have not been studied or compared to one another. Identifying these produced relationships would be a first step in using body shape within CAD patternmaking systems to produce custom-fit apparel.

Key Locations of Body-to-Pattern Relationship for Trousers

The relationship of the body to the pattern around the center front and center back of the lower torso, between the legs, is unique to bifurcated garments. On a pattern, this generally U-shaped line, joining at the inseam, is called the crotch curve. The measurement along this line is the crotch length. The part of the crotch curve that lies between the legs is termed the crotch extension, and the ease amount in the crotch extension is a key factor in proper fit of bifurcated garments (Lin, 2014). The specific shape of this curved pattern line and the ease contained in the crotch extension is a product of following the steps of each pant drafting method. Additional key circumference measurement locations for trouser fit for women are waist, hip, thigh, knee, and ankle.

Summary and Research Purposes

Apparel mass customization is a promising solution to women’s fit problems with bifurcated garments. Patternmaking is a key component of apparel mass customization systems. Unfortunately, the body-to-garment relationships produced by these systems have not been predictable or clearly identified in previous research. The researchers aimed to identify and compare the body-to-pattern relationships produced by two commonly used pattern-drafting methods (Aldrich, 2008; Joseph-Armstrong, 2010). In doing so, the implicit theoretical principles of body-to-pattern relationships comprising these methods are made explicit. By understanding these principles explicitly, the apparel mass customization theoretical framework (Lu et al., 2010) may be improved. The body-to-pattern relationship identified may become a controllable variable within the apparel mass customization system, which is controlled by the selection of a pattern-drafting system. A second aim of the researchers was to test whether these produced relationships are consistent for various bodies. A third purpose was to identify the specific processes as well as any inconsistencies within these patternmaking systems that may cause these body-to-pattern relationships, so that recommendations for a better system could be proposed. Such an improved patternmaking system may allow for quick, accurate, and reliable computer-aided custom garment pattern-drafting and the advancement of apparel mass customization.

Research Questions

The overarching purpose of the researchers was to identify the effectiveness of current patternmaking methods as a basis for computer-aided patternmaking systems for use in apparel mass customization of women’s trousers. Thus, the following research questions were proposed.

What are the body-to-pattern measurement relationships in trouser patterns drafted according to the Joseph-Armstrong and Aldrich methods for waist, hip, thigh, knee, and ankle circumferences; crotch length; and crotch extension?

Are these measurement relationships consistent between the two drafting methods?

Are these measurement relationships consistent within each drafting method for different body shapes of the same hip sizes?

What is the body-to-pattern shape relationship in trouser patterns drafted according to the Joseph-Armstrong and Aldrich methods for the crotch curve?

Is this shape relationship consistent between the two drafting methods?

Is this shape relationship consistent within each drafting method for different body shapes of the same hip size?

What pattern-drafting procedures cause these body-to-pattern relationships?

Method

A case study research strategy (Yin, 2003) was used. The study design was similar to that used by McKinney et al. (2012), with body-to-pattern relationships of custom-fitted pant blocks investigated by comparing body and pattern measurements/shapes. Trouser sloper patterns were drafted for six forms using two patternmaking methods for a total of 12 cases. Body-to-pattern measurement and shape relationships were assessed within each case. A cross-case analysis was used to compare the produced relationships between methods and within each method.

Sample

Body form selection

Body forms, rather than actual people, were used in this study as a consistent way to obtain measurements due to the stable measurement landmarks on the forms and their symmetry and stability when captured by body scanning. Because one of the major purposes was to investigate body-to-pattern relationships and consistency among bodies of various shapes or proportions while isolating the size variable (Figure 1), a purposive sampling strategy was used to select six full forms from different manufacturers, time periods, and countries that represented different shapes but had hip measurements within the same size category (Table 1). All forms had hip measurements between 92 cm (36.2 in.) and 96 cm (37.8 in.), equivalent to a UK size 12, according to Aldrich (2008). Forms were measured for comparison following the detailed guidance of Beazley (1997).

Figure 1.

Crotch shape and hip depth of the full body forms.

Table 1.

Dress Form Characteristics.

Form #	Brand	Year	Country	Waist	Hip
1 (UK 12)	Alvanon	2007	UK	70.4	97.0
2 (US 6)	Alvanon	2007	UK	69.5	95.2
3 (US 8)	Wolf	2003	US	64.8	91.8
4 (US 10)	Wolf	1992	US	67.3	94.3
5 (US 12)	Wolf	2013	US	69.2	95.7
6 (US 10)	Wolf	2013	US	66.0	92.4

Note. Measurements in cm.

Pattern selection

The US “trouser-foundation 2” method from Joseph-Armstrong (2010, pp. 573–576, 583) and the UK “classic tailored trouser block” method from Aldrich (2008, pp. 100–101) were used. The rationale for these selections was that these texts are used extensively at all levels in the education of students as well as by industry professionals, and they appear as key texts in many libraries where clothing product development is taught.

Pattern Drafting

Two trouser patterns were created for each form using the selected US and UK drafting methods. Collection of body form measurements used in the drafts followed the instructions provided in the respective texts for each pattern-drafting method, as it was previously established that different methods have subtle differences in measurement definitions (Gill & Chadwick, 2009). The two methods required different units of measurement: imperial inches for Joseph-Armstrong (2010) and metric centimeters for Aldrich (2008). Each pattern was drafted following the instructions of each process by a pattern technician with 5–10 years’ experience of pattern-block creation in both education and industry. Then, each draft was checked against the methods by a pattern technician with 20 years’ experience of block creation in industry, teaching, and research contexts. The patterns were completed according to common pattern-drafting procedures that ensure the pattern is trued along curves and lines run at correct angles to produce a pattern with no sharp angles and fluid lines at the seams and edges (Aldrich, 2008; Joseph-Armstrong, 2010).

Pattern Measurement and Shape Extraction

The completed trouser patterns were digitized with Optitex in the United States and Gerber in the United Kingdom, and the electronic patterns were printed and checked against the originals for accuracy. The digital patterns were then converted to a common Gerber format. Measurements were taken (in centimeters) from each pattern using the Gerber AccuMark Ver.8 software measurement tools and were placed in accordance with lines or notches related to where they were applied in the draft process. Measurement data were exported to a Microsoft Excel spreadsheet, where all analysis was undertaken. Digital pattern shapes were exported as .dxf files and converted to 1/4-scale images for processing with CAD software (CorelDRAW Graphics Suite X5) for analysis.

Body Measurement and Shape Extraction

Body form measurements taken following the instructions of Beazley (1997) were entered into the spreadsheet for comparison with the pattern measurements. Arc body form measurements taken for drafting (Joseph-Armstrong, 2010) were used for separate analyses of fronts and backs at the waist and hip. The forms were scanned with a TC² NX16 in the United States and a TC² KX16 in the United Kingdom to capture digital images of body shape. It was necessary to create a chin point and abduct the arms of the forms to capture readable scans that could be analyzed by the TC² software as .rbd files. Digital images of the crotch curves were captured by isolating the crotch length (the measurement from the center front waist to the center back waist passing through the lowest point of the torso, defined as the crotch point) and waist circumference measurements of the forms using the TC² software and taking screenshots from the side of the scans with the grid view set as a means to calibrate (Figure 1). The crotch shapes were then traced from the images of the scans using image-editing software for comparison to the pattern shapes. Size and aspect ratios were maintained throughout the process.

Data Analysis

Following the frameworks used by Gill and Chadwick (2009) and Gill (2011), the body-to-pattern measurement relationships at the waist, hip, crotch, knee, and ankle were calculated for each case. To quantify the relationship, percentage ease level (the difference between the body form measurements used in the draft and corresponding parts of the pattern, as a percentage of the body measurement) was used because it allowed for comparison between forms and methods. To analyze the shape relationship, form crotch shapes were layered with the pattern crotch shapes using an overlay technique similar to Bye et al. (2008). Cross-case analysis was conducted within and between methods for both measurements and shapes. Then, the individually drafted patterns and the pattern-drafting texts were looked at again. Each step of the pattern-drafting process was considered to determine its impact on the resulting body-to-pattern relationships. This included analyzing the mathematical operations applied to specific body measurements in each step of each drafting method to understand the complete mathematical formulas applied to body measurements to derive pattern line lengths. One of the most complex examples is crotch extension (Figure 2). Lengths, widths, and edges (e.g., waist circumference) of pattern pieces were measured and compared to the length expected based on the identified formula. Inputs used (e.g., direct vs. indirect body measurements), mathematical operations applied to these inputs, and ease amounts added were considered for their impact on each pattern piece’s final measurements and shape. The impacts of using these drafting systems in a mass-customized apparel system are discussed and alternative processes are suggested.

Figure 2.

Relationship of pattern measurements to the body for selected drafts.

Results

Body-to-pattern measurement relationships in trouser patterns drafted according to the Joseph-Armstrong and Aldrich methods—waist, hip, thigh, knee, and ankle circumferences as well as crotch length—are presented in Figure 3. Percentage ease levels at key locations were different between the two methods and within methods when patterns were drafted for various body forms. Pattern ease levels were not consistent derivatives of the body measurements used. Patterns drafted from the same form had different shapes and measurements depending on the method used. Body-to-pattern shape relationships in trouser patterns drafted according to the Joseph-Armstrong and Aldrich methods for the crotch curve were not consistent (Figure 4). If applied in an apparel mass customization system, these body-to-pattern fit relationship inconsistencies would result in differences in the way the garment fits the body and sometimes even the style of the garment. The uncontrolled nature of these inconsistencies would also make it difficult to apply previous experience in making amendments.

Figure 3.

Percentage ease levels at key circumferences and lengths.

Figure 4.

Comparison of crotch curves of patterns and dress forms by drafting method.

Between Methods

Measurement

Body-to-pattern measurement relationships for the same body were not consistent between the two drafting methods. However, the degree of these inconsistencies varied by location. Joseph-Armstrong consistently added a greater percentage ease level at the waist, 4.0% (3.5–4.4%), in some cases up to double compared to Aldrich, 1.8% (1.1–3.6%). This excess amount can be eased into the top of the trouser waistband, but there would be a difference in garment style and the inclusion of fullness in the trouser below the waistband. At the hip, Aldrich resulted in greater ease, 6.5% (5.1–7.9%), compared to Joseph-Armstrong, 5.5% (4.6%–6.0%), reflecting a slightly looser style. Ease at the thigh was comparable between the methods, Aldrich providing an average of 16.9% (14.9–17.6%) and Joseph-Armstrong providing 16.1% (15.0–17.2%). The ease level of the crotch length was less consistent between the methods and, in most cases, negative: Aldrich provided an average of −1.6% (−3% to 0.8%) and Joseph-Armstrong provided an average of −1.9% (−4.7% to 0.2%). At the knee and ankle, there was greater variability in the ease level percentages. Average ease levels provided at the knee were 28% (25–32%) for Aldrich and 34% (30–39%) for Joseph-Armstrong; at the ankle, they were 46% (40–52%) for Aldrich and 45% (39–47%) for Joseph-Armstrong.

Shape

The body-to-pattern shape relationship of the crotch curve between the two drafting methods was not consistent. For Joseph-Armstrong, the start of the curve in the line of the pattern was less related to the points of maximum curvature among the body forms than for Aldrich. Joseph-Armstrong provided a more consistent curve between the hip level and crotch (Figure 1), the placement of which did not accurately reflect the variation of hip heights and points of maximum curvature among the body forms (Figures 1 and 5). This likely accounted for the higher degree of consistency in the positioning of the hip in the Joseph-Armstrong drafts in contrast to those of Aldrich (Figure 4). In Aldrich’s patterns, there was less of a corresponding body-to-pattern relationship than those of Joseph-Armstrong in the lengths of the front and back crotch extension portions of the crotch curve. Joseph-Armstrong had a shorter front extension, resulting in a more acute angle between the hip and crotch point, which would also impact the position of the inside leg seam relative to the body, particularly in the positioning of the inseam. Aldrich provided a deeper front crotch extension and a more varied back crotch extension. The crotch extension on both sets of patterns showed differences in their depth (Figure 4) and did not relate to the variation of the hip and crotch curves of the forms (Figure 1). Neither of the tested methods seemingly provided variation to truly reflect the different shape of each form, particularly in regard to the front-to-back body depth or the angle of the crotch curve (Figures 1 and 4).

Figure 5.

Crotch extensions calculated from the hip against body depths at the hip from scans.

Although the intention was to focus on the crotch curve shape, during the visual analysis other shape differences between methods that resulted in important fit and style differences between the final patterns became apparent. Differences in trouser leg pattern shapes between the two drafting methods were evident: Aldrich produced a longer-shaped and Joseph-Armstrong a shorter-shaped pattern. Further, the number of darts used on the front of the trousers differed, and the darts were pitched in Aldrich’s draft whereas they were vertical in Joseph-Armstrong’s.

Within Methods

Measurement

Measurement relationships were not consistent for different body shapes of the same hip sizes within each of the drafting methods. For both Joseph-Armstrong and Aldrich, highest variability was seen in percentage ease levels at the crotch length. For Aldrich, there was also high variability for percentage ease levels at the waist.

Shape

Body-to-pattern shape relationships were also not consistent for different body shapes of the same hip size within each drafting method. Crotch shapes of the patterns were similar within each drafting method (Figure 4), despite the crotch shapes of the forms being different (Figures 1 and 4). This resulted in inconsistent body-to-pattern shape relationships.

Pattern-Drafting Procedures Causing These Body-to-Pattern Relationships

Measurement

Some inconsistencies between methods were due simply to differences in ease amounts added directly to corresponding body measurements (e.g., at the waist and hip). Others were caused by the two methods using different body measurements to establish garment dimensions. However, a number of other drafting procedures may have caused body-to-pattern relationship inconsistencies both within and between methods. Often, two or more of these causes interacted.

Inconsistencies in percentage ease levels in some locations may be attributable to some of the trueing, blending, and connecting steps in the pattern-drafting process. These steps caused alterations to the added ease levels found in the finalized pattern. The waist is a key area where this may have caused different final measurements than those intended by the drafting method. In the process of plotting a waistline, a series of vertical and horizontal lines are plotted and connected with a slightly diagonal line. Then dart legs intersecting this line are redrawn (trued) to make them equal in length, causing the waistline to be redrawn.

Inconsistencies may also be attributable to the use of proportions of noncorresponding body measurements to plot pattern lines. Crotch extension is determined as a proportion of the total hip circumference (Aldrich, 2008) or arcs of its circumference (Joseph-Armstrong, 2010) plus an allowance (Figure 2). A key difference between the two methods is in the measurement procedures for the waist and hip: Aldrich’s measurements are taken fully around the body circumference, whereas Joseph-Armstrong splits the circumference into front and back arcs from center seam to side seam (illustrated in Figure 2). The crotch extension in the Joseph-Armstrong method depends on the back and front arc size and the balance between them, returning a larger extension when more of the balance of the hip is within the back arc. This practice seems to be common with a number of existing pattern-drafting methods, all of which define the crotch extension relative to the hip circumference (Campbell, 1980; Holman, 1997; MacDonald, 2010).

The crotch extension affects the crotch length. The process for defining the crotch line length is complex for both methods. Neither method required a crotch length measurement to be applied during the drafting process. Rather, this curved line resulted from drafting the crotch depth and crotch extension and then connecting the two with a curved line. Pattern crotch depth was determined from direct body measurement plus a controlled level of ease in both methods. Crotch extension (as discussed above) was a proportion of a noncorresponding measurement.

Inconsistencies may also be attributable to the use of standard measurements (with no relationship to body measurements) used to draft pattern lines or define connection points for curves. Neither knee nor ankle dimensions are applied during the draft process. Each uses a set measurement. There is no consideration of levels changing due to individual criteria.

Shape

Pattern-drafting procedures cause the resulting body-to-pattern shape relationships. The pattern crotch curve shape may be described by the placement of hip level, length of crotch extensions, and crotch angle. Differences between the methods in the relationship between the start of the curve in the line in the pattern and the points of maximum curvature on the body may be attributable to the positioning of the hip line in the pattern-drafting procedures. This is an important step because it acts as a break point for drawing the curve of the crotch into the crotch extension. The Aldrich method utilizes the body waist-to-hip length to set the hip level; in contrast, the Joseph-Armstrong method sets the hip depth as two thirds of the waist-height to crotch-height measurement (measured up from the crotch level). Differences between the methods in the lengths of front and back crotch extensions may be attributable to the fact that Joseph-Armstrong’s front and back crotch extensions are based on body hip front and back arc measurements, respectively, whereas Aldrich’s are based on the entire circumference. If there is a correspondence between hip circumference and body front-to-back depth, Aldrich’s drafting procedures may result in less of a corresponding body-to-pattern relationship.

The pant leg’s shape may be described in terms of its length and width. Aldrich’s longer pant length can be traced to the use of measurements in defining the shape. Joseph-Armstrong measures length to the ankle, whereas Aldrich uses length to the floor. Aldrich also creates more shaping in the leg width, utilizing a contour line to the knee to provide a narrower silhouette.

Conclusion

The two tested trouser pattern-drafting methods cannot be used to consistently control or predict garment ease, which has a direct bearing on garment fit and style. These inconsistencies are due to the pattern-drafting procedures used within a particular method. Using different drafting methods will result in garments with different fit in terms of measurement and shape.

If apparel mass-customization system operators wish to continue to use these drafting methods as the basis of their systems, they must consider the consequences of each patternmaking step on produced body-to-pattern relationships to understand and plan for each step’s impact on the fit and style of the final garment. Furthermore, it must be acknowledged that the fit and style of the produced garment will differ with the patternmaking method selected. The specific method as well as the body-to-pattern relationships contained therein must be considered as part of the total theoretical framework surrounding apparel mass customization. Beyond mass customization, this finding has impacts for companies that do business in multiple countries if different methods are used to draft basic block patterns.

Implications

Neither of the investigated trouser pattern-drafting methods is suitable for use in computer-aided custom patternmaking due to the inconsistent body-to-pattern measurement and shape relationships that occur when their steps are followed. These methods are particularly poor as a basis for trousers produced as mass-customized apparel because the crotch curve, a key area for proper fit in bifurcated garments, had the least consistent body-to-pattern relationships in both measurement and shape. These inconsistencies are rooted in the pattern procedures themselves. The use of proportions implicit in pattern-drafting methods do not allow the crotch extension to change in relation to lower body width, back-to-front depth, size, and shape variation found within a population, as indicated by Song and Ashdown (2012) and Hlaing et al. (2013).

It is not possible for these pattern shapes to reflect the individual variation in the proportion or balance of the dress forms or figure used. It would be very difficult to predict what fit these methods would produce for computer-generated custom patterns for a range of body sizes and shapes. Beyond the crotch curve issues, the pattern-drafting process, in general, makes it difficult to know what the final measurements will be, making pattern corrections a necessary step and limiting the possibilities for computer-aided custom pattern-drafting.

Recommendations

It is clear that pattern-drafting methods are rooted in an era when measurement of the human body was difficult, and certain measurements were easier to extract as proportions of other measurements. Moreover, differences between body and pattern, currently addressed only at the fitting stage, could be addressed earlier in the process. There are problems with current pattern-drafting systems that researchers must resolve before quick and accurate mass-customized apparel products can be achieved. Based on these findings, recommendations were developed to improve the consistency of body-to-pattern relationships in drafted patterns.

Issues of ease inconsistency due to connecting, trueing, and blending steps in current methods may be improved by adding a final step of checking the pattern measurements and correcting them to equal the corresponding measurements plus the desired ease amount. This solution, however, cannot address the inability of these methods to maintain body-to-pattern relationships for bodies of varying shapes and proportions. There needs to be a more linear relationship between the body and the pattern, using a greater number of direct measurements. A new pattern-drafting method that uses body measurements and shapes to develop corresponding pattern measurements and shapes, which are available through 3-D body scanning, must be developed. Measurements different than those used in the current drafting methods may be added or substituted. There would be no need to use a proportion of a noncorresponding body measurement. For example, front-to-back body depth measurement (as a measurement of a 3-D body scan shown in Figure 1) could be used to draft crotch extensions appropriate for individual body shapes. Based on visual analysis of the trouser to the body, we propose that body front-to-back hip depth, rather than a proportion of hip, would be a more logical and corresponding guide for the pattern crotch extension. To test this proposition, pattern crotch extensions calculated using the formulas established from this analysis (Figure 2) were compared to the scan-derived measurements; the difference between them is shown in Figure 5. The drafted crotch extensions would be less than the body measurement by an average of 5.42 cm (range = 4.56–5.99 cm) using Aldrich (2008) or 4.37 cm (range = 3.45–5.13 cm) using Joseph-Armstrong (2010), seemingly not a direct relationship. In McKinney et al.’s (2012) study of body-to-pattern relationships found in basic pant sloper patterns custom-fit to seven participants, the best fit for all participants had a crotch curve shape narrower than body depth at hip level (differences ranged from 8.1 to 4.0 in.).

Currently, there is no incorporation of body shape (e.g., the 2-D shape of the crotch curve, body front-to-back depth, or body side-to-side width) in the drafting methods. Hip depth can be classified and categorized (McKinney et al., 2012; Song & Ashdown, 2012); however, existing methods of pattern drafting do not have the facility to relate to these varied hip depths. Current methods are based solely on surface measurements and height measurements. Scholars should conduct research to understand body-to-garment relationships that result in good fit and to incorporate 3-D body shape into pattern-drafting methods. Such research will be especially useful for apparel mass customization systems that attempt to create patterns in 3-D as an offset of the body. If it were known what ease amount produced a good fit, this could be incorporated into the 3-D patternmaking system.

Limitations and Future Research

The researchers limited this study to consideration of women’s UK size 12 trouser pattern blocks in two methods. However, based on the reasons uncovered for the inconsistent body-to-pattern relationships caused by these methods, these problems likely also exist for other sizes or types of pattern blocks. The researchers limited body-to-pattern shape relationship aspects considered in this study. For example, hip shape was not considered. Crotch shape was chosen as a focus, as it is a known source of fit problems for bifurcated garments.

Even with the proposed new pattern-drafting system based on corresponding body measurements, a number of unanswered questions remain. How many body measurements should be used? Which body measurements should be used? How much ease should be added? Should the added ease be a proportion of the measurement or a set amount? Finally, is the current pattern configuration of center front, center back, and side seams, with fullness controlled at the waist by darts, the best way to create a pattern block to fit the continuum of human body shapes?

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was partially funded by a First-Year Honors Mentor Program Grant from the Iowa State University Honors Program.

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