I'm gonna hit up a few posts I've had in my mind for a little while, and as a temporary "theme" I thought I'd concentrate a little more on physical animation ( seeing as that's actually what I do most of the time ) and some of the tips associated with that type of movement.
So... "Feet First" ... ok...
What this post is about is a quick way to ground an animation with a sense of weight and force, and then worry about all the other parts after that. I'm trying to explain the idea of "contact points"... the point(s) of the character's physical structure that are generating momentum and push. I like to concentrate on this early on in animation, and it never lets me down.
For a start its always good that when you come to "animate" your scene ( as opposed to the blocking stage ) to start with something first and get it feeling solid. Animation is just way too hard anyway, without trying to think and animate everything at once. As an example, many animators will start by working detail and smoothness into the characters main movement point ( usually the "root", e.g the hips or the waist of the character ) because it makes sense to do that as the root is often first to drive a full body movement... and the rest of the body will generally inherit movement from this. This is a pretty basic animation concept, and a good one to use.
Work "from the top down"
But where is the "top" really ?
What really leads the movement? ok.. so really its the thought, the motivation, all the cerebral stuff, and this could go pretty subjective because it can depend a lot on the scene and what the character is doing, but I find that for physical animation, a lot of the time its the points of contact that lead the action! So most of the time its the feet, or maybe the hands ( if your character was doing push ups for example ) or the elbow if your guy is leaning on a bar.
If you think about it, the root of the character cannot actually move itself. when you twist your hips, you're using mostly your legs to do this. When you shift your weight, your hips might appear to move first and drive the movement, but really that movement is being generated by the legs and feet!
The root can only move itself if the legs stop pushing, there are no other points of contact ( e.g no bar to grab onto ) and gravity brings the root downwards.
If they're not leading a direct movement, they at least drive the overall weight and grounding of a character that is very important to get right in physical stuff.
As a working example, I recently animated a pretty complex action, where a guy is lunging forward a few metres and supposed to be not very firm on his feet and a little lacking in confidence. I wanted to get the feet shifting nicely and that idea of him "catching himself" almost as if he was just about to fall over.
So I blocked all my main poses first ( I actually used each new foot plant as a key, then I set a breakdown between each plant ) ... then I jumped straight in and started to animate the feet and the root, and took them both pretty near final. Once I had that working, with a nice sense of timing and weight and force, I could have fun with the rest of the body. Its not just because the feet movements were important to this animation, I would also do this if there were only a few plants or a simple weight shift.
For most physical stuff you will find that if you animate the feet and the root together, get the timing and weight feeling right, then its much easier to animate the rest of the character, because the main driving forces are established and already working.
Working between changes in contact points sets up good "markers" that you can work around. You know that's where key forces are either constant, moving to, or moving from.. and a lot of the nice overlap and subtle stuff that you like to animate are direct results of these changes... so start there.