the system updates the 2D pattern so that the simulation
result matches the user input. This guarantees that the
model is always realizable as a real plush toy and that the
2D pattern is readily usable as a template for cutting and
sewing real fabric.
The modeling operations are based on the Teddy system.
11 The user interactively draws free-form strokes on the
canvas as gestures and the system automatically generates
a 3D model and corresponding 2D cloth pattern. 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 the resulting plush toy by applying a simple
physical simulation (Figure 5).
Cut: The user can cut the model by drawing a stroke that
starts outside of the model, crosses it, and ends outside of
the model (Figure 6). The model is cut at the intersection and
flat patch is generated at the cross-section. This operation is
useful for creating relatively flat surfaces, such as those in a
foot or belly.
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 that defines the silhouette of the part. The stroke
should start and end on the base model (Figure 7a). The system generates two candidate shapes and presents them to
the user as suggestions9 (Figure 7b). One is for fat, rounded
parts like the body, arm, and leg (Figure 7c). Their base is
connected to the base model with an open hole. The other
candidate shape is for thin parts like ears and the tail
whose base is closed (Figure 7d). The user clicks the desired
Figure 5. Creating a new model.
Figure 6. Cut operation.
Figure 7. user interface of part creation. (a) the user draws a stroke
and (b) the system suggests two different possibilities. the user
chooses one (c, d).
Figure 8. user interface of the pull operation.
thumbnail and the system updates the main model accordingly. We found that the ability to create thin parts with a
single stroke is particularly useful. They are frequently seen
in real toys and are difficult to design using standard modeling software. Figure 20 shows a couple of example models
with thin parts.
Pull: The user can grab a seam line and pull it to modify
the shape. For example, the user can pull an ear to make it
larger when it is smaller than the other (Figure 8). The pulling operation begins when the user starts dragging on the
background region near a 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.
12 to adjust the size of the
region to be deformed, that is, the larger area is deformed
as the user pulls more. The system continuously updates the
2D cloth pattern during pulling and shows the simulation
result in the 3D view.
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 is especially important
when using nonstretchy cloth as in balloon models because
one needs to divide a rounded surface into many almost-developable small patches (Figure 19 bottom).
The user can add a new seam in the seam line drawing
mode by drawing a free-form stroke on the model surface
(Figure 9). The corresponding cloth patch is then automatically cut along the new seam line. If the stroke crosses
the entire patch, the patch is divided into two separate