Character Animation: The Fun Part - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 320

move their feet that way when they walk sideways or backwards. In those cases, people generally place
their toe first, then plant the heel. This requires only a slight alteration of the procedure outlined above.
When walking backward, instead of clearing the foot bone's rotation (step 9), you leave it alone. Instead,
you key the heel bone right on that frame. This pose looks like the toe is striking the ground first. Then,
you advance two frames (or just one if things are moving quickly) and clear the foot bone's rotation,
effectively planting the heel.
With the feet done though, it's time to refine the rest of the body. First up is the body_control bone.
The body rises and falls as you walk. The highest point is when one foot is at its own highest point off
the ground, and the body's weight is borne completely by the other foot. When the weight is evenly
distributed on both feet, the body is at its lowest point. Scrub through the timeline, stopping at each high
and low point. Move the body_control bone up or down at those points. A lot of vertical travel will make
your walk look silly. That might be what you want, depending on your animation goals. However, we're
going to try to keep it at least semi-realistic.
The Web Bucket video body_control_adjustment.mpeg shows the difference. Not only has the vertical posi-
tioning of the upper body been adjusted, but some of the later motion too. There were a few places where
the placement of the feet seemed a little off in comparison to where the body was, and also where the
body perhaps moved too quickly. So, a simple adjustment and new key here and there helped to fix it.
While working on fixing the overall body motion, it's important to keep an eye on the legs. What you're
looking for is called “IK pop.” It happens when an IK limb like a leg is pushed to its fullest extension.
At that point, the chain of bones “pops” completely straight. It is obvious in an animation when this
happens, and should be avoided. So, as you adjust the upper body of your character, make sure that you
are not moving it so far that either of the legs pops.
When you're satisfied with the interaction between the feet placement and the upper body, turn your
attention to the arms and hands. Arms move in opposition to feet. When the left foot is back, the left
hand is generally forward, and vice versa. With Auto IK enabled, this is simply done by finding the key-
frames on which both of the feet are on the ground and pulling the hands appropriately. This is another
area like body control where more motion will give a cartoonish feel, while less will tend toward realism.
Depending on how much time you have, you can carefully craft these arm poses, based on your own
observations of walking. How are the hands rotated at the forward and backward extremes? On the frame
midway between the extremes, how close is the hand to the hip? You might need to insert an additional
keyframe there to make sure it doesn't pass through the body in certain cases.
As a last pass through, you can also rotate the spine. Once again, how “loose” do you want your walk to
be? How much jive? The upper spine should rotate in opposition to the feet, just like the hands. The
right should rotate forward when the left foot proceeds.
Watch the Web Bucket video not_horrible.mpeg , which is where we're at right now. It's not horrible. It's
not really good, though. Unfortunately, this is where the artistry kicks in. Sure, you can go in and add
overlap to the arms. You can maybe even add a hold here or there if the walk is slow and things begin