Pillow: Interactive Pattern Design for Stuffed Animals
Yuki Mori†
The University of Tokyo

Takeo Igarashi*
The University of Tokyo / JST PRESTO

1. Introduction

This sketch describes an interactive pattern design system forcreating stuffed animals. The user imports a 3D model into thesystem and specifies the segmentation boundaries interactively bydrawing seam lines on the model surface. Given the user-definedsegmentation, the system generates a 2D pattern by flattening thepieces [Lectra]. The system then visualizes the shape of theresulting stuffed animal by applying a simple physics simulation
to the virtual stuffed animal created by assembling the flattenedpieces. This closed loop framework allows the user to experimentwith various seam patterns before actually working on real fabricto obtain the best-looking result.
Julius et al. [2005] presented an automatic segmentation
algorithm for stuffed animals and demonstrated its viability bycreating real toys using the machine-generated pattern. However,their automatic method relies on purely geometric criteria and it isdifficult to capture the perceptually important features of theoriginal shape. As a result, seams can appear in undesirable ways,
such as those that cross the face or ignore the symmetry of themodel. Our approach focuses on the user’s artistic process ofpattern design and provides tools to support the exploration
process.

(a)
(b)
(c)
Figure 1. Outline of our system: (a) The original 3D model withseam lines drawn by the user; (b) 2D sawing patterns generated byflattening the pieces; (c) The reconstruction result generated byapplying a physics simulation to the pattern.

2. User Interface
Figure 1 shows a snapshot of the system. The left window shows
the original 3D model, the center window shows the flattened 2Dpattern, and the right window shows the reconstruction result.
This system takes a 3D surface model as input. The user draws
free-form lines on the 3D model surface indicating thesegmentation boundaries (Fig. 1(a)). When the user completes thesegmentation, the system automatically flattens the pieces (Fig.
1(b)). The pattern view shows lines connecting corresponding
seams to help the user understand the relationships among thepieces. The system also reconstructs the 3D geometry by virtually
sewing the flattened pieces together and applying a simple physics
simulation (Fig. 1(c)). This view visualizes how the stuffed toy
might look when the user creates a real toy using the current†email: yukim@acm.org*email: takeo@acm.org

segmentation. If the user dislikes the result, he or she can quickly
change the segmentation by erasing and redrawing seam lines.

3. Implementation

Pillow, our prototype system, is implemented as a Java™ program.
Flattening and reconstruction run in real-time on a standard PC.
We use ABF++ as the flattening algorithm [Sheffer 2005]. For thephysics simulation, we currently use a very simple mass-springmodel, but plan to combine our system with more sophisticatedsimulation methods [Grinspun 2002].

4. Result
We created 2D patterns for a teddy bear model using our systemand then created real stuffed animals using the resulting patterns.
Figure 2 presents the result. It shows that the user can quickly
experiment with various segmentation strategies using the system,and the simulation results successfully capture the overall shapeof the real stuffed animals.

Figure 2. Pattern design examples. The user experiments withtwo different segmentations (top and bottom). The figures show
(left) the user-specified seam lines, (center) the result of applying
the physics simulation to the patterns generated automaticallyfrom the user-specified segmentation, and (right) the real stuffedanimals created using the given patterns.

Acknowledgments
We would like to thank Bruno Lévy for providing the OpenNL
library. We also thank Dan Julius for his helpful comments.

References
GRINSPUN, E., KRYSL, P., and SCHRÖDER, P. 2002. CHARMS: asimple framework for adaptive simulation, ACM Transactions
on Graphics, 21, 3, 281-290.
LECTRA, Design Concept Furniture.
JULIUS, D., KRAEVOY, V., and SHEFFER, A. 2005. D-Charts: QuasiDevelopable Mesh Segmentation, Computer Graphics Forum(Proc Eurographics 2005), 24, 3, 981-990.
SHEFFER, A., LÉVY, B., MOGILNITSKY, M., and BOGOMYAKOV., A.
2005. ABF++: Fast and Robust Angle Based Flattening, ACM
Transactions on Graphics, 24, 2, 311-330.