What is the Line of Action
The line of action goes hand in hand with making a character’s pose
easier to read. Think of the line of action as an imaginary line running
down a character’s spine. The line of action is a curved line. Making
the line of action curved, as opposed to drawing it as a straight line,
gives your character’s pose more force and attitude which, in turn, aids
in making your character’s poses more visually interesting to the
viewer.
The line of action is a simple curved line that evokes movement.
Avoid making your line of action S-shaped or straight – it will hinder
the overall force and make the resulting pose look less dynamic.
Below are examples of poses utilizing a strong line of action. Note
that even though the character may be standing "still", there is still
an attitude being projected, simply by having the torso coincide with
the line of action.
When drawing from life, find the line of action – note it down, and
then proceed to exaggerate it. It’ll make the resulting pose feel more
"alive" and less stiff.
In the example below, we can see that as the line of action is made
more horizontal, the character’s run appears to be getting faster.
To give our character poses even more variety, we can twist the torso
against the hips. By "breaking the plane", we automatically add depth
to a pose. Coupled with rendering foreshortened elements of the body,
the possibilities are endless.
Conclusion
The line of action can make your character poses more dynamic and easier to read. Give it a try on your next character design!