Automatically Adding Seam Allowance to Cloth Pattern
Yuki Igarashi1
Takeo Igarashi 1,21
The University of Tokyo
1. Introduction
Various methods have been proposed for novice users to design
their own garments using computers recently [Igarashi andHughes 2002; Turouin et al. 2007]. These systems automaticallygenerate a 2D cloth pattern from user input and the user can createa real garment by sewing the pattern together. To sew a real fabric,
one also needs to leave an appropriate seam allowance whencutting the two-dimensional (2D) pattern. Difference seamallowances result in different look of the resulting garment [Hu etal. 1997], so appropriate design of seam allowance is very
important. However, traditional computational pattern generation
methods did not automatically generate seam allowances mainly
because the target users were expert users and they prefer tomanually add seam allowances. However, it is difficult for anovice user to add appropriate seam allowance manually and it isdesirable that the system automatically create cloth pattern thattakes seam allowance into account.
Naïve approach is to generate seam allowance of equal widtharound the pattern (Figure 1a). However, it can cause problems in
actual sewing as shown in Figure 1b. In this case, inappropriate
seam allowance leaves loose end in the final garment because
zigzag stitch cannot hold the folded part. To obtain a professional
looking result, one needs to consider the geometry of cloth pattern
after folding at the seam lines Figure 1c,d.

2

Hiromasa Suzuki1
JST ERATO

seam and to 14mm for lap-felled seam, top stitched seam andFrench seam as suggested by a professional designer. To computethe shape of seam allowance, the system first computes a distancefield around the cloth pattern and then traces its iso-contour of thefield. We compute distance field at discrete grid points and thentraces the iso-contour using marching square method.
Special treatment is applied at the corner of the cloth patternwhere curved seam and straight seam meets. In this case, straightseam is folded first and then curve seam is finished by zigzag
stitches (this is because it is typically difficult to fold curved
seams). For each such a corner, the system sets the boundary
shape of the seam allowance along the curved seams (zigzagstitch) so that that it exactly matches after folding at the straightseams (Figure 1).
Table 1: types of seam allowancetypes ofillustration
seamallowanceseamallowance
on a 3D
modelseamallowance
on a 2D
patternlap-felled
seam

top
stitchedseam

French
seam

(a)

(b)

zigzagstitched
seam

References
IGARASHI, T., AND HUGHES, J. F. 2002. Clothing manipulation. In Proc. of
15th Annual Symposium on User Interface Software and Technology(ACM UIST 2002), 91-100, 2002.

(c)(d)
Figure 1: An Example of problematic cases (sleeve placket).

TURQUIN, E. , WITHER, J., BOISSIEUX, L., CANI, M.-P., AND HUGHES, J. A
sketch-based interface for clothing virtual characters. IEEE ComputerGraphics & Applications, 27(1), 72-81, 2007.

2. Implementation

Hu, J., Chung, S., Lo, M.-T. Effect of seams on fabric drape. International
Journal of Clothing Science and Technology, 9(3), 220-227, 1997.

The current system supports four seam types as shown in Table 1:
lap-felled seam, top stitched seam, French seam and zigzag
stitched seam. As a default, the system creates a seam allowancewith equal width around the cloth pattern. We set the width ofseam allowance to 7mm for lap-felled seam and zigzag stitched