Patchy: An Interactive Patchwork Design System
Yuki Igarashi∗
University of Tsukuba / Meiji University(a)

(b)

(c)

(d)

Jun Mitani
University of Tsukuba

(e)

(f)

(g)

Figure 1: System overview. (a) The user designs patchwork pattern silhouettes using a painting interface. (b) Then the user designs a color
fabric pattern. (c) The system automatically adds stitch strokes. (d) Then the user can design stitch strokes using a free-form stroke, (e) pulla silhouette stroke, (f) pull a stitch stroke, and finally (g) sew the patchwork.

1Introduction

Patchwork is a well-known type of needlework that involves sewing
pieces of fabric into a larger design. It is commonly used to form
quilts, but can also be used to make bags, wall hangings, cushion covers, and other items. Larger designs are usually based on
repeating patterns, which are built up using different shapes. Professional patchwork designers design original patterns; however,novice users usually use geometric patterns or off-the-shelf patterns
for each piece; this is because it is difficult for novices to design
patterns while visualizing the resulting larger fabric.
Here we propose an interactive system to assist the design of original patchwork patterns. Coahranm and Fiume [2005] presented
a sketch-based design system for a specific quilting artform, i.e.,
Bargello patterns. They described an algorithm that transforms
sketched input data into graceful Bargello curves. In contrast, with
our system the user designs original patchwork strokes. The user
can design original patchwork patterns using various fabric colors
through a process of trial and error.

2User Interface

Figure 1 shows an overview of the process. The user first designs
patchwork pattern silhouettes using a painting interface (Fig. 1a).
Then s/he designs fabric patterns through trial and error, as shownin Figure 1(b). The user draws two types of stroke: a silhouettestroke, which is the border of the pieces of fabric, and a stitch stroke,
which is a stitch line on the pieces of fabric. The system automatically adds stitch strokes, as shown in Figure 1(c). The user can also
design stitch strokes using a free-form stroke (Fig. 1d), and thensew the patchwork, as shown in Figure 1(g).
As shown in Figure 1(e,f), the user can grab a stroke and pull it
to deform the shape of the stitch lines using the peeling interface
introduced by Igarashi et al. [2005]. When s/he drags and drops a
texture image into a domain bounded by silhouette strokes, the system updates the region inside this area. The user can also examine
the overall color balance in a distant view using the zoom tool.
∗ e-mail:yukim@acm.org

3

Implementation

Our prototype system was implemented in JavaTM , and demonstrated in real-time on a 2.1-GHz CoreTM i7 PC. The system uses ahybrid approach combining vector and raster representations. The
user’s strokes are stored as vector graphic primitives, and the systemrenders the strokes and texture as a raster image after computing thenormals.
The system computes thenormals of the cells after
the user inputs or modifies
a stroke, as shown in Figure
2. The target normal n of acell v(x, y) is computed as
the normal of a height field
Figure 2: Computation of nordefined bypmals.
22r − (r − d) (d < r),h(d) =r(d ≥ r)
where d is the distance to the closest stroke and r is a constantparameter; we used r = 30. Then the system applies smoothing toeach normal 50 times.

4Results

We used our system to create patchwork designs, and then the resulting pattern was manually sewn, as shown in Figure 3. Eachdesign session typically required 10 − 15 min, and the sewing required 3 − 5 h. Users can quickly experiment with various patterns
using the system before beginning sewing.

Figure 3: Example patterns designed using Patchy.

ReferencesC OAHRANM , M., AND F IUME , E. 2005. Sketch-based designfor bargello quilts. In Eurographics Workshop on Sketch-BasedInterfaces and Modeling 2005, 165–174.
I GARASHI , T., M OSCOVICH , T., AND H UGHES , J. F. 2005.
As-rigid-as-possible shape manipulation. ACM Transactions on
Computer Graphics (ACM SIGGRAPH 2005) 24, 3, 1134–1141.