Graphics Reference
In-Depth Information
If we now consider the timing of the walk, we can see how acceleration
and deceleration during certain phases work together to create the whole
dynamic. The speeds of the two strides, both left and right, are the same in a
normal walk. The timing of the right and left actions may vary and become
uneven when a figure walks with a limp or when one side of the figure is
constricted in some way or is carrying a heavy load on one side.
1
6
11
16
FIG 5.32 Basic timing of a walk
cycle. 1, 6, 11, and 16 represent keys.
2 3
4
5
7
8
9 10
12 13 14 15
I have lost count of the times young undergraduate animation students have
asked me how many frames there are in a walk cycle. This usually happens
when they first attempt to animate a human walking. I can understand
why they would ask this question as they search for an easy answer to
what appears to be a straightforward problem. Unfortunately, there are
a number of other texts that state quite clearly a prescribed number of
frames for the action. This does little except make for preconceptions and
muddy the waters. The truth is that the problem is far from straightforward
and the timing of a walk cycle will vary greatly depending on a number of
circumstances, many of which we have touched on. The walker's physicality,
age, and health; the surface on which she is walking; even the shoes she is
wearing may have an effect on the timing of the action as well as the nature
of the gait.
It bears repeating that it is both the length of the stride and the frequency
with which the steps are taken that determines the speed of a walk.
As the figure goes through the walk cycle, the body rises and falls throughout
the action. When the figure reaches the passing position, notice that the
head is at its highest point in the cycle. As with the speed of the walk, the
degree to which the figure rises and falls is determined by the stride length,
but the degree to which the legs are bent at the knees also determines the
dip in action. The greater the bend, the bigger the dip is. There are very few
examples when a walking figure presents a much flatter action.
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