I first learned about the "Line of Action" (shortened "LOA" in my notes) reading John K.'s excellent animation blog ( http://johnkstuff.blogspot.com/ ). The concept is summed up in this picture by Preston Blair:
Arguably the most dynamic-looking poses are those which can be synthesized with just one or two lines of this kind. There is much information about using LOAs to draw human and human-like bodies in motion, but I couldn't find much about using it for animal motion, such as running horses or birds in flight seen from od angles.
So I found it very instructive to study animal photos and decide out which lines stand out in each pose for me. They are the lines which might serve as LOAs for drawing that pose. (Sorry for the unreadable notes in the pictures - these were the last sketches I did like that before sticking to uppercase.)
Solid red lines are the lines I see most prominent in the original. Dashed red lines are the ones I used, which I thought made the pose slightly better looking.
Things I noticed in these first experiments:
- Drawing with LOAs in mind is useful when using photos as references, to avoid the temptation of just copying exactly the photo.
- If at the end of the main line there is a part of the body pointing in a different direction, e.g. a muzzle or a limb, it adds to the feeling of movement. See the bats and dolphin. If the muzzles followed the solid line the bodies would look a bit too simple.
- Making a LOA turn into a spiral is necessary to draw certain animal bodies, especially when odd tails are involved. There is no way to draw a nice chamaleon using just the Blair rule of slightly curved lines...