STEP 1: Use exaggerated proportion to make it look handmade
A key to tricking the eye into believing we’re looking at something
handmade is in the relationships of proportion. Although a real puppet
builder might aim for realism, there are usually elements that retain a
hand-built nature. For instance, when constructing Abe Lincoln (see
below), we used very simple geometry to make his hat look like it could
be molded plastic. His head is very large in proportion to his body,
and his hands are very tiny. His jacket has large and obvious thread
detail, helping to reinforce the illusion of scale. In this short,
Abe’s proportions help him read as a small puppet.
STEP 2: Rig your character
When attaching a character to a rig, we usually try to achieve a
smooth, realistic deformation. To simulate the look of a puppet that’s
been rigged with some type of armature, we want to break from that
tendency. The rig in this step is based on the
Softimage|XSI 4.2 default rig, which includes a
curve-based spine. It gives us a good basis for our puppet armature.
Although we have more controls than we will actually use, it still lets
us set up quickly.
STEP 3: Use as few deformers as possible when enveloping
When applying a flexible envelope, use the minimum number of deformers
per point. In other words, each point should be mostly influenced by no
more than one deformer. This will cause a more rigid breaking of the
geometry during animation. Some smoothing will still be necessary, but
keep it to a minimum since we are trying to mimic an armature with
clothing. XSI has an "Apply Smooth" function that makes this quick and
easy. As you can see in this image, Abe’s arm is unacceptable for most
purposes, but this distortion happily aids us in our goal of attaining
a stop-motion look.
STEP 4: Use replacement parts
Stop-motion animators commonly use a technique that involves swapping
out parts of a puppet. For instance, swapping mouth parts creates the
illusion of lip-sync. Tim Burton’s Jack Skellington character from his
film The Nightmare Before Christmas had over 40
replacement heads. These are referred to as "replacement parts," and we
will apply this concept to our model as well. The procedure is the same
as regular shape morphing, but rather than letting the computer assist
interpolation, you can keyframe shape changes over a single frame. We
all know that smooth blending at the push of a button is easy in XSI,
but once again, you need to resist the temptation to achieve your goal.
Limit the computer’s influence by using blend shapes and changing
quickly from one shape to the next.
STEP 5: Light the scene
"Final gathering" is an algorithm that speeds up global illumination,
lending realistic lighting to your scene. Most 3D programs today have
incorporated some type of this form of rendering, which lets you
achieve a level of realism with very little effort. Using a large
"bounce card" object, you can cast a soft, diffuse light over your set.
I won’t go into detailed instruction on how to use final gathering in
this tutorial. But, in this case, a lavender-colored dome over the set
is producing almost all of the lighting in the scene.
STEP 6: Controlling your character
Probably the most important aspect of emulating stop motion is how you
shape your animation curves. A stop-motion animator may try to achieve
smooth motion when it is appropriate, but will hold poses and use
larger position offsets when the action is less important. You can
mimic this style by combining spline interpolation keys with hand keys
and constant interpolation. In constant mode, each keyframe’s value is
simply held until the next keyframe. In this example, Lincoln’s arm
effector has a mix of constant interpolation and spline interpolation.
As he rolls the snowball forward (see image, Step
1), his motion is smooth, as if the animator had done frame-by-frame
Rob Cazin founded So! Animation in New York in 1992 as an open creative
environment; a full-service design studio soon formed, built on a core
of superior technology and artistic excellence. At So! Rob leads the
Softimage|XSI animation team and provides original music and sound
effects for independent films and broadcast branding. A recognized CGI
pro, Rob has written in-depth articles for various trade publications
and has won an Emmy. So! holds dozens of other industry awards.
Rob Says Keep In Mind…
This tutorial outlines the guiding principles and techniques that can
give your 3D animation a traditional stop-motion look. Although this
particular project was done in Softimage|XSI version 4.2, each step is
generalized to apply to most 3D applications.
There are many other tricks that you can use to create a stop-motion
feel. Try adding "jitter" to your "replacement parts" by rotating the
part slightly at some of your shape keyframes. Or bend the ear of one
of your heads, as if it were damaged in handling.
Another common trick is to apply film grain and/or damage using one of the many plug-ins that are available.
The final version of this Holiday ID short, which we did for the
History Channel, can be viewed at
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