Plushie: An Interactive Design System for Plush Toys
Yuki Mori∗
The University of Tokyo(a) creation(b) cut

Takeo Igarashi∗
The University of Tokyo / JST, PRESTO(c) adding a part(d) pull(e) result of sewing

Figure 1: Designing an original plush toy using our system. The user interactively edits the 3D model on the screen using a sketchinginterface. Internally, the system generates 2D cloth pattern and shows the 3D model as a result of applying simple simulation to the pattern.

Abstract

1

We introduce Plushie, an interactive system that allows nonprofessional users to design their own original plush toys. To design aplush toy, one needs to construct an appropriate two-dimensional(2D) pattern. However, it is difficult for non-professional users
to appropriately design a 2D pattern. Some recent systems automatically generate a 2D pattern for a given three-dimensional (3D)
model, but constructing a 3D model is itself a challenge. Furthermore, an arbitrary 3D model cannot necessarily be realized as a realplush toy, and the final sewn result can be very different from theoriginal 3D model. We avoid this mismatch by constructing appropriate 2D patterns and applying simple physical simulation to it on
the fly during 3D modeling. In this way, the model on the screen isalways a good approximation of the final sewn result, which makes
the design process much more efficient. We use a sketching interface for 3D modeling and also provide various editing operations
tailored for plush toy design. Internally, the system constructs a 2D
cloth pattern in such a way that the simulation result matches theuser’s input stroke. Our goal is to show that relatively simple algorithms can provide fast, satisfactory results to the user whereas the
pursuit of optimal layout and simulation accuracy lies outside thispaper’s scope. We successfully demonstrated that non-professional
users could design plush toys or balloon easily using Plushie.

A computer can be a powerful tool for designing real-world artifacts. One can build a virtual model in a computer and use it
to run various simulations, without the need to build and damage
costly real objects. The benefits are evident in many areas, fromarchitecture to automobile design. In these traditional applications,modeling and simulation have been completely separated. A virtual model is created in three-dimensional (3D) modeling software
without considering any physical constraints, and then passed later
to a simulation environment. If the simulation result reveals a problem, the user returns to modeling to fix the problem. This can be
more efficient if the system runs the simulation concurrently withmodeling, so that only models that are physically realizable are created. In this way, the user can more efficiently explore the design dimensions within realistic constraints. From the user’s point of view,the model generated by the system may not exactly take his/her input shape but takes a physically realizable shape reflecting the input
shape.

CR Categories: I.3.6 [Computer Graphics]: Methodology andTechniques—Interaction Techniques; I.3.5 [Computer Graphics]:
Computational Geometry and Object Modeling—Geometric Algorithms
Keywords: plush toys, sketch-based modeling, cloth simulation∗ e-mail: {yukim, takeo}@acm.org
ACM Reference Format
Mori, Y., Igarashi, T. 2007. Plushie: An Interactive Design System for Plush Toys. ACM Trans. Graph. 26, 3,
Article 45 (July 2007), 8 pages. DOI = 10.1145/1239451.1239496 http://doi.acm.org/10.1145/1239451.12
39496.
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© 2007 ACM 0730-0301/2007/03-ART45 $5.00 DOI 10.1145/1239451.1239496
http://doi.acm.org/10.1145/1239451.1239496

Introduction

Some recent systems have tried to incorporate physical simulation
into an interactive design process. Igarashi and Hughes [2002] developed a mark-based interface for putting clothing on a virtual
character, and Decaudin et al. [2006] proposed a system for designing an original garment via sketching. Both used simple geometricsimulations to represent the physical properties of cloth material.
Masry and Lipson [2005] described a system in which the user canquickly build a CAD model via sketching and immediately apply
finite element analysis to the model. However, model construction
is computed before simulation in these systems, and no dynamic
feedback loop exists between the simulation result and the originaluser input.
We are experimenting with modeling guided by a concurrent simulation in plush toy design. Plush toys are one of the most familiar
objects in our daily life but their design is difficult. One must design
an appropriate two-dimensional (2D) pattern to obtain a particular
3D shape, but the relationship between the two is nontrivial, andintensive experience and knowledge is required to do so appropriately. As a result, most people simply buy ready-made toys and do
not enjoy the design and construction of their own plush toys. We
have tried to enable these people to design their own toys by providing an easy but powerful modeling tool that combines a sketchinginterface and integrated physical simulation.

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Mori et al.
We use relatively simple algorithms as a proof of concept to provide immediate feedback to the user. More sophisticated, off-line
algorithms for texture atlas generation [Milenkovic 1999; Bruno
et al. 2002] and cloth simulation [Grinspun et al. 2002; Choi andKo 2002; Breen et al. 1994] have been studied in textile industry.
It is our future work to explore a way to apply these sophisticatedmethods to interactive setting.
(a) Traditional framework2(b) Our framework
Figure 2: Designing a plush toy with a computer. Traditional approach (a) first constructs an unconstrained virtual model and generates a 2D pattern by applying segmentation and flattening. The
final sewn result can be very different from the virtual model. Our
system (b) directly generates 2D cloth pattern such that the simulation result matches the user input. In this way, the virtual model isalways a good estimation of the final sewn result.

Methods for making plush toys from a given 3D model have been
proposed in recent years. Mitani and Suzuki [2004] and Shatz etal. [2006] presented automatic segmentation of a 3D model into developable patches for constructing paper craft models. Similarly,
Julius et al. [2005] proposed automatic segmentation and flatteningof a model for plush toys. One problem of an automatic approachthat relies on purely geometric criteria is that it is difficult to perceptually capture important features such as symmetry. Mori and
Igarashi’s [2006] system helps manual segmentation of a model by
providing automatic flattening and showing the result of physicalsimulation. These systems make plush toy design more accessible,
but the fundamental challenge of creating an original plush toy is
still unresolved. One can generate simple models using some modeling software (e.g., [Igarashi et al. 1999; Karpenko and Hughes
2006]) but an arbitrary 3D model is not necessarily realizable as areal plush toy, and the final sewn result can be very different fromthe original 3D model (Figure 2 a).
Our system, Plushie, allows the user to create a 3D plush toy modelfrom scratch by simply drawing its desired silhouette. The user
can also edit the model, such as by cutting the model and adding
a part, using simple sketching interface. The resulting model is always associated with a 2D pattern and the 3D model is the resultof a physical simulation that mimics the inflation effect caused by
stuffing. Therefore, the model on the screen is always a good estimation of the final sewn result (Figure 2 b). Internally, the systemcomputes the geometry of the 2D pattern so that the simulation result matches the user’s input sketch. This is a nontrivial inverse
problem and we address this by using simple iterative adjustment
method. We show that a very simple simulation method, just moving vertices to their normal directions to mimic pressure and pullingthem back to maintain edge length, works well for our applicationand provides an unprecedented experience of designing a physicalobject in a computer. We run a workshop in a museum to havenovice users try our system and have observed that even children
can design their own plush toys.
Our contribution is in the overall design of the interactive system.

User Interface

The system consists of two windows: one shows the 3D plush toymodel being constructed and the other shows the corresponding 2D
pattern (3). The user works on the 3D view, interactively building
the 3D model by using a sketching interface. The 2D view is mainly
for reference but the user can also edit the 2D pattern directly whendesired. The 3D model is produced from a physical simulation of
the assembled 2D pattern. After each input from the user, the system updates the 2D pattern so that the simulation result matches theuser input. This guarantees that the model is always realizable as areal plush toy and that the 2D pattern is readily usable as a templatefor cutting and sewing real fabric.

Figure 3: A screen snapshot of the Plushie system.

2.1

3D Modeling Operations

The modeling operations are based on gestural interface introducedby Igarashi et al. [1999]. The user interactively draws free-form
strokes on the canvas as gestures and the system performs corresponding operations. We also provide some special editing operations tailored for plush toy design.
Creating a New Model: Starting with a blank canvas, the user
creates a new plush toy model by drawing its silhouette as a closed
free-form stroke. The system automatically generates two cloth
patches corresponding to the stroke and visualizes the shape of theresulting plush toy by applying a simple physical simulation (Figure 1 a).
Cut: A cut operation makes relatively flat surfaces, such as thosein a foot or belly. A cutting stroke should start outside of the model,
cross it, and end outside of the model (Figure 1 b). The model is cutat the intersection and flat patch is generated at the cross-section.
Creation of a Part: The user can add protruding parts such as
the ears and arms to the base model by drawing a single stroke thatdefines the silhouette of the part. The stroke should start and end on
the base model (Figure 4 a). The system generates two candidate
shapes and presents them to the user as suggestions [Igarashi andHughes 2001](Figure 4 b). One is for fat, rounded parts like thebody, arm, and leg (Figure 4 c). Their base is connected to the

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patch. Deletion is achieved by tracing the target seam line in theerasing mode. This merges the separated patches together and thus
flattens the area (Figure 7).

Figure 4: User interface of part creation. (a) The user draws astroke and (b) the system suggests two different possibilities. The
user chooses one (c, d).

(a)

(b)

(c)

(d)

Figure 6: Insertion of a seam line. (a) Before drawing a line. (b)After drawing a line. (c) The seam line’s two endpoints snap atother seam lines. (d) After pulling the seam line.

base model with an open hole. The other candidate shape is forthin parts like ears and the tail, whose base is closed (Figure 4 d).
The user clicks the desired thumbnail and the system updates themain model accordingly. We found that the ability to create thinparts with a single stroke is particularly useful. They are frequently
seen in real toys and are difficult to design using standard modelingsoftware. Figure 18 shows a couple of example models with thinparts.
Pull:
The user can grab a seam line and pull it to modify theshape. For example, the user can pull an ear to make it larger when
it is smaller than the other (Figure 5). The pulling operation begins when the user starts dragging on the background region neara seam line. The system changes the mouse cursor when it approaches a seam line to indicate that the user can start pulling. We
use the peeling interface introduced by Igarashi et al. [2005] to adjust the size of the region to be deformed; that is, the more the user
pulls, the larger the area of the deformed region. The system continuously updates the 2D cloth pattern during pulling and shows thesimulation result in the 3D view.

Figure 5: User interface of the pull operation.
Insertion and Deletion of Seam Lines:
The modeling operations performed thus far automatically generate 2D patches according to predefined algorithms and seam lines (patch boundaries)
appear on the 3D model surface without the user’s explicit control. However, it is sometimes desirable for knowledgeable users
to design seam lines manually, for more detailed control. This isespecially important when using non-stretchy cloth as in balloon
models because one needs to divide a rounded surface into many
almost-developable small patches (Figure 17 right).
The user can add a new seam in the seam line drawing mode bydrawing a free-form stroke on the model surface (Figure 6). The
corresponding cloth patch is then automatically cut along the newseam line. If the stroke crosses the entire patch, the patch is divided
into two separate patches. If the stroke starts or ends in the middle
of a patch, it becomes a dart. The 3D geometry does not change
immediately after the insertion of these seam lines, but the user canpull the seam line afterwards to modify the shape. This operationis very useful for creating a salient feature in the middle of a flat

Figure 7: Deletion of a seam line.

2.2

Operations on the 2D Pattern View

The 2D pattern view is mainly used to preview the pattern to beprinted for sewing, but it also works as an interface for advanced
users to edit the pattern directly. The preview helps the user to understand the relationship between the 3D model and 2D patches andgives a sense of the labor required for assembling the patches. The
system can display how patches are connected by showing connectors or paired numbers (Figure 8). Connectors are useful for understanding the relationship on the screen and numbers are usefulas a printed reference on each patch. The system provides an automatic layout and manual arrangement interface for preparing thefinal pattern to be printed.
The system also allows the user to edit the patches directly by using the pulling interface. The user can grab the boundary of a patch
and pull it to deform the shape [Igarashi et al. 2005]. We again
use a peeling interface to adjust the size of area to be deformed.
The effect of 2D deformation immediately appears in the 3D view
because of the physical simulation. The ability to deform an individual patch is useful for designing asymmetric shapes such as a
penguin body (Figure 9, Figure 18). The pull operation is also useful for opening a dart line to make a flat patch swell more (Figure
10).

3Implementation

We use standard triangle mesh for the representation of 3D modeland the 2D patches. We use relatively coarse mesh (1000-2000 vertices) to achieve interactive performance. Each vertex, edge, andface of the 3D mesh is associated with corresponding entities in
the 2D mesh. A 3D mesh is always given as a result of applying aphysical simulation to the assembled 2D pattern. To be more precise, the physical simulation applied to the 3D mesh is governedby the rest length of each edge, which is defined in the 2D meshgeometry. For each modeling operation, the system constructs the

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Mori et al.

Figure 10: Opening a dart line.
(a)

(b)

(c)

Figure 8: Patches connected to each other using connectors (b)and numbers (c).

(
tij =

0.5 · (vj − vi ) ·0|vi −vi |−lij|vi −vj |ifif|vi − vj | ≥ lij|vi − vj | < lij(3)

where lij represents the rest length of an edge eij .
The second part (adjustment of edge length) runs ten times in eachcycle to prevent excessive stretch. It takes approximately 30 simulation cycles (2 seconds) to converge in our typical examples. The
parameter setting in our current implementation is a = 0.02 andb = 1. Although it is possible to show the result only after the convergence, we decided to show the intermediate shape because test
users preferred to see the inflation process.

Figure 9: Pulling a 2D patch.

initial 2D patches and the 3D geometry corresponding to the input
stroke, and then runs a physical simulation to update the 3D geometry. The system then adjusts the patch shape so that the simulation
results match the input strokes. This section describes these implementation details.

3.1

Physical Simulation

We use a simple static method for the physical simulation. We
examined other, more elaborate methods, such as finite element
methods [Grinspun et al. 2002], dynamic simulation [Choi and Ko2002], and energy minimization [Breen et al. 1994], but we foundthat the simple approach is best suited for our purpose. It is easy
to implement, fast enough for interactive modeling, and sufficiently
robust for dealing with adverse user operations. More importantly,
it produces a reasonable estimation of the resulting plush toy shape.
As shown in Figure 14, it successfully reproduces characteristic behaviors seen in the stuffed cloth.
In each simulation cycle, the system first moves each face slightly in
its normal direction to mimic the effect of internal pressure (Figure11 a). The displacement of a vertex vi is computed as a weighted
sum of the neighboring faces (Fi )’ displacements:Pvi + = αf ∈FiPA(f )n(f )f ∈Fi A(f )(1)where A(f ) is the area of a face f and n(f ) is the normal of theface.
The system then adjusts the length of each edge to preserve the integrity of the cloth material [Desbrun et al. 1999] (Figure 11 b). We
decided to prevent stretching only and tolerate compression because
plush toys’ rotund shape is generated from compression (small winkles) along the seam lines. The displacement of a vertex vi is computed as a weighted sum of the forces (tij ) from the neighboringedges (Ei ):P
eij ∈Ei {A(e.leftface) + A(e.rightface)} tijvi + = β P(2)eij ∈Ei {A(e.leftface) + A(e.rightface)}

(a)

(b)

Figure 11: Our simple model to mimic stuffing effect. (a) the system
first moves each face to its normal direction slightly to mimic theeffect of internal pressure. (b) the system adjusts the length of eachedge to preserve the integrity of cloth material.

3.2

3D Modeling

Creating a New Model: The input stroke is projected onto an
invisible plane at the center of the world facing the screen, andthe system generates an initial two-sided mesh inside of the closed
region. Each side of the mesh is used directly as a 2D patch forthe model. The system then applies the physical simulation to themesh. It inflates the mesh to the direction perpendicular to the viewing direction, but its silhouette actually becomes smaller as it inflates (Figure 12). The system waits until the simulation converges
and then starts to adjust the 2D pattern so that the simulation result matches the input stroke. Specifically, the system calculates
the distance di from a vertex vi of the 3D mesh along the seam line
to the corresponding point pi in the projected input stroke along
its normal direction, and moves the corresponding 2D vertex ui on
the patch boundary in its normal direction by that amount di (Figure 12). We prevent self-intersection by detecting collision duringvertex relocation. After modifying the patch boundary, the system
updates the 2D mesh by applying Laplacian smoothing constraining the boundary vertices (Figure 13 d):PPParg min{ vi |vi − |N1i | vj ∈Ni vj |2 + vi ∈B |vi − vi 0 |2 } (4)viwhere Ni is the one ring neighbor of vi and B is the boundary.
The length of the edges in the updated 2D mesh is then used as
the new rest length in the simulation. The system repeats this adjustment process and the physical simulation until convergence. We
also apply simple gaussian smoothing to the boundary curve once in

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Plushie: An Interactive Design System for Plush Toys

Figure 12: Adjustment process after creation. The system enlarges
the 2D pattern so that the simulation result matches the input stroke.
The 2D boundary vertex (v) moves in its normal direction by theamount proportional to the distance between the corresponding 3Dvertex and the input stroke.

(a)

(b)

(c)

(d)

Figure 13: Updating the 2D mesh geometry. (a) before deformation. (b) boundary vertices are moved. (c) smoothing is applied tothe boundary. (d) Laplacian smoothing is applied to the internalvertices.

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Figure 14: Physical simulation and shape adjustment. The redlines indicate the input strokes. The top row shows the result of converting the input into patterns directly, and the bottom row shows
the outcome when the adjustment process is applied to the patterns.
The green shapes in the middle show the simulation results and thebrown ones on the right show the real fabric models, both resulting
from the 2D pattern on the left.

initial 3D geometry for the added part. As in the initial model creation case, the flat two-sided 3D mesh is inflated by physical simulation. The silhouette of the added part gradually shrinks and thesystem enlarges the 2D pattern so that the silhouette matches the
input stroke as in initial creation.
In case of a part with an elliptic base curve, the system cuts open
the base surface and stitches it with the newly created mesh. The
result is a single connected mesh, and physical simulation is applied
uniformly to the entire mesh. On the other hand, the system does
not open the base mesh in case of the linear base curve. The newpart is created as an independent closed mesh and the simulation
is applied separately to the base mesh and the new part. The basemesh inflates independently of the part mesh, and the base curve istreated as a positional constraint in the simulation of the part mesh
(we simply do not move these vertices in the simulation cycle).

every five iteration cycles to maintain smoothness along the boundary (Figure 13 c). It takes approximately 20 iterations (2 seconds)
to converge in our typical examples.
This simple algorithm works well in practice for our application.
Figure 14 shows some examples in which our algorithm successfully found appropriate 2D patches that yielded the desired 3D
shapes. In some situations, the input shape is not realizable as aplush toy model consisting of two patches. For example, a sharp
concavity is not realizable without causing self-intersection in the2D patch. In these cases, the system terminates the optimization process, leaving a gap between the input stroke and the 3Dmodel. This indicates that the desired shape is not possible withtwo patches. The user must add additional seam lines to obtain
more control.
Cut:
The system constructs a curved surface by sweeping the
cutting stroke on the screen in the viewing direction and dividing
the mesh along the surface. The right-hand side of the surface isremoved and a new mesh is created on the cross-section. The crosssection is always developable, so the system simply flattens it anduses it as a 2D patch.
Creation of a Part: The system first projects the two endpointsof the input stroke onto the base model surface. A plane that passes
through these 3D points and is facing toward the screen is constructed and the input stroke is projected onto it. The system thendraws an ellipse on the model surface for constructing a fat part anddraws a line for creating a thin part (Figure 15). The ellipse or theline (what we call base curves) is also projected to the plane. The
system generates a 2D mesh on the projection plane in the area enclosed by the projected input stroke and the projected base curve.
The 2D mesh is duplicated and serves as 2D pattern and as the

(a)

(b)

(c)

Figure 15: Creation of a part. The system projects the input stroke
to a working plane and cuts the base mesh with either an elliptic
curve or a line (b). The 3D geometry is constructed by creating amesh between the projected stroke and the base curves (c).
Pull:
The pull operation is a bit involved because the systemcannot directly modify the 3D mesh and must do so indirectly by
deforming the corresponding 2D pattern. As the user starts pulling avertex on a seam line, the system first constructs a projection planethat passes through the seam line (Figure 16). The mouse cursor
position on the screen is projected onto the projection plane, and it
is used as a target position for the pulled vertex during subsequentdragging. The system computes the displacement δi in the local
coordinate frame on the projected plane from the original positionvi to the target position hi , and moves the corresponding vertices
ui 0 and ui 1 in the 2D mesh in their local coordinate frames by that

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amount δi . These 3D and 2D coordinate frames are defined by thepulled vertex’s normal vector and the direction of the seam line. As
in the adjustment process after the initial creation, the system updates the 2D mesh by applying Laplacian smoothing and then uses
the result to define the new rest edge length for guiding simulation.
The system iterates this displacement process with physical simulation until it converges. To achieve a smooth deformation, the system also moves the surrounding vertices in the 2D mesh using the
curve manipulation method introduced in Igarashi et al. [2005]. It
enlarges the region to be deformed proportional to the displacementof the pulled vertex.

Figure 17: A plush toy and a balloon designed in our system.

Figure 16: Pulling a vertex on a seam line.
Insertion and Deletion of Seam Lines: Insertion of a new seamline is straightforward. The system simply cuts the patch along
the added seam line and updates the meshes accordingly. Deletionis more complicated because the merged patch is not necessarily
developable. The system applies an approximate flattening operation [Sheffer et al. 2005] to the merged 3D surface to obtain thegeometry of the new 2D patch.

4

Results

Plushie is implemented as a JavaTM program. Construction of 2D
patterns and a physical simulation run in real-time on a 1.1 GHz
Pentium M PC. We designed a couple of plush toys using our system and created a real toy based on the printed pattern. A modelingsession typically takes 10-20 minutes and sewing takes 3 -5 hours.
Figure 17 shows a plush toy and balloon model designed in oursystem. It shows that the physical simulation successfully captures
the overall shape of the real objects. We interviewed with professional balloon designers and they supported our system, saying thatit can significantly reduce the time necessary for designing original
balloon.
The user can assign different textures to individual patches (Figure18). Therefore the user can explore various design possibilities before actuary sewing the real fabric (such as Figure 18 right). Thesemodels also demonstrate the effectiveness of thin parts.
We ran a small workshop to have novice users try our system. Nine
children, 10-14 years old, joined the workshop accompanied bytheir parents. We gave a brief tutorial at the beginning and had them
design their own plush toys using the system. It took about an hourfor the design. They then printed the designed pattern and seweda real toy in approximately 3 hours. Figure 19 shows a couple ofplush toys created in the workshop. Participants quickly learned
how to use the system and successfully designed the 3D models
they wanted, with some help from volunteers. Furthermore, they
enjoyed the process. These toys were their own creations and oneof-a-kind designs. Participants also gave us valuable feedback for
future improvement. They wanted to have some auxiliary functions

Figure 18: Example of texture changed. These models have manythin parts.

such as the ability to design symmetric parts and remove existingparts, but no one complained about the quality of the visual simulation. A perfectly accurate simulation is not necessary because
many small variations inevitably occur during the real sewing andstuffing process.

5

Limitations and Future Work

Our 3D pull operation works well for inter-patch seams as shown in
Figure 6, but not for intra-patch seams, i.e., darts. If the user pulls adart line outward in the 3D view, the system tries to move the corresponding patch boundary to the normal direction, which causes
a self-intersection within the patch (Figure 20 left). We currently
rely on the 2D pull operation to open a dart as in Figure 10, but wewould like to allow more intuitive operation on the darts in the 3D
view. For example, we want the system to automatically open thedarts, for example, when the user pulls a dart outward in the 3Dview (Figure 20 right).
We currently do not consider the bending energy in our simulation,
so the material is a bit too flexible. Based on the experience of
our users, this is not a serious problem for most target materials,
but appropriate treatment of bending can extend the applicability of
our system to more inflexible materials such as felt and leather. We
plan to prepare several predefined material parameters and allow
the user to choose the desired setting for each target material.
Apart from adding a miscellaneous utility function to the system,
we would like to incorporate more domain knowledge into the system so that an inexperienced user can design more sophisticatedACM Transactions on Graphics, Vol. 26, No. 3, Article 45, Publication date: July 2007.

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B REEN , D. E., H OUSE , D. H., AND W OZNY, M. J. 1994. Predicting the drape of woven cloth using interacting particles. In
Proceedings of SIGGRAPH 1994, 365–372.
B RUNO , L., S YLVAIN , P., N ICOLAS , R., AND J EROME , M. 2002.
Least squares conformal maps for automatic texture atlas generation. ACM SIGGRAPH 02, 362–371.
C HOI , K. J., AND KO , H. S. 2002. Stable but responsive cloth.
ACM Transactions on Graphics (Proceedings of SIGGRAPH
2002) 21, 3, 81–97.

Figure 19: Example of original plush toys designed and created bychildren in the workshop.

D ECAUDIN , P., J ULIUS , D., W ITHER , J., B OISSIEUX , L., S HEF FER , A., AND C ANI , M. P. 2006. Virtual garments: A fully
geometric approach for clothing design. Computer Graphics Forum (Proceedings of Eurographics 2006) 25, 3, 625–634.
D ESBRUN , M., S CHR ÖDER , P., AND BARR , A. 1999. Interactive
animation of structured deformable objects. In Proceedings ofGraphics Interface 1999, 1–8.
G RINSPUN , E., K RISL , P., AND S CHR ÖDER , P. 2002. Charms: A
simple@framework for adaptive simulation. ACM Transactions
on Graphics (Proceedings of SIGGRAPH 2002) 21, 3, 281–290.

Figure 20: Limitation of our 3D pulling operation.

patterns. For example, it is necessary to insert several darts into a
patch if the user wants to have it swell more. We would like to develop an intelligent interface that allows the user to pull the centerof a patch to its normal direction and then automatically insert darts.
It would be also interesting to provide an intelligent guide to help
the sewing process, such as showing the user the order in which
they should sew the patches [Agrawala et al. 2003] and providing
an estimate of the time required to complete the sewing.
Interactive 3D modeling assisted by concurrent physical simulation
can be a powerful tool in many application domains. For example,
if one can run an aerodynamic simulation during the interactive design of an airplane model, it might be helpful to intelligently adjust
the entire geometry in response to the user’s simple deformation
operations so that it can actually fly. This kind of interaction would
make it easier for designers to pursue aesthetic goals while satisfying engineering constraints. Real-time simulation does require
high-performance computing resources, but some meaningful support should be possible by carefully limiting the target task and designing appropriate interfaces as shown in this paper. We hope that
our work inspires future work in this direction.

Acknowledgements
We would like to thank Dennis Cosgrove for providing Jalice scenegraph. We also thank Hiromasa Suzuki, Jun Mitani, and Olga
Sorkine for their helpful comments. We also thank National Museum of Emerging Science and Innovation in Japan for offering theplace to run the workshop and “Quest And Try” Inc. for making theballoon. Finally we thank the user interface research group at the
University of Tokyo for helpful discussions.

References
AGRAWALA , M., D OANTAM , P., H EISER , J., H AYMAKER , J.,K LINGNER , J., H ANRAHAN , P., AND T VERSKY, B. 2003.
Designing effective step-by-step assembly instructions. ACM
Transactions on Graphics (Proceedings of SIGGRAPH 2003)
22, 3, 828–837.

I GARASHI , T., AND H UGHES , J. F. 2001. A suggestive interface for 3d drawing. In Proceedings of 14th Annual Symposium
on User Interface Software and Technology (ACM UIST 2001),
173–181.
I GARASHI , T., AND H UGHES , J. F. 2002. Clothing manipulation. In Proceedings of 15th Annual Symposium on User Interface Software and Technology (ACM UIST 2002), 91–100.
I GARASHI , T., M ATSUOKA , S., AND TANAKA , H. 1999. Teddy:
A sketching interface for 3d freeform design. In ACM SIGGRAPH 1999, 409–416.
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.
J ULIUS , D., K RAEVOY, V., AND S HEFFER , A. 2005. D-charts:
quasi developable mesh segmentation. Computer Graphics Forum. (Proceedings of Eurographics 2005) 24, 3, 981–990.
K ARPENKO , O. A., AND H UGHES , J. F. 2006. Smoothsketch: 3dfree-form shapes from complex sketches. ACM Transactions on
Graphics (Proceedings of SIGGRAPH 2006) 22, 3, 589–598.
M ASRY, M., AND L IPSON , H. 2005. A sketch-based interface
for iterative design and analysis of 3d objects. In Proceedings ofEurographics Workshop on Sketch-Based Interfaces, 109–118.
M ILENKOVIC , V. J. 1999. Rotational polygon containment andminimum enclosure using only robust 2d constructions. Computational Geometry 13, 1, 3–19.
M ITANI , J., AND S UZUKI , H. 2004. Making papercraft toys frommeshes using strip-based approximate unfolding. ACM Transactions on Graphics (Proceedings of SIGGRAPH 2004) 23, 3,
259–263.
M ORI , Y., AND I GARASHI , T. 2006. Pillow: Interactive patterndesign for plush toys. In DVD publication at SIGGRAPH 2006
Sketches & Applications.
S HATZ , I., TAL , A., AND L EIFMAN , G. 2006. Paper craft models
from meshes. The Visual Computer: International Journal ofComputer Graphics (Proceedings of Pacific Graphics 2006) 22,
9, 825–834.

ACM Transactions on Graphics, Vol. 26, No. 3, Article 45, Publication date: July 2007.

45-8

•

Mori et al.

S HEFFER , A., L ÉVY, B., M OGILNITSKY, M., AND B O GOMYAKOV, A. 2005. ABF++: Fast and robust angle based
flattening. ACM Transactions on Graphics 24, 2, 311–330.

ACM Transactions on Graphics, Vol. 26, No. 3, Article 45, Publication date: July 2007.