Today I'm posting a little bit of guesswork, or in other words: pose analysis from photos, with a focus on hips and chest. Lots of animators like to analyze lines of action, shape-stuff, and not so much anatomical stuff like chest, hips, spine, and the relationship between them. It's pretty hard to think in terms of "the real thing" and much more comfortable to just draw a fluid line of action. Not to say that lines of action are a breeze to master or maybe not even a big deal... au contraire. Lines of action are a thing to watch for in animation, and not only along the spine and limbs of the character, but also as a composition per se, the whole pose should flow naturally, and also in a group, multiple characters should have a visual flow.
Anyway, today is not about shapes, it's about rotations.... What does that chest do in a pose? Or the hips. The spine is then a result of the relationship hips-chest. Of course, in cartoony animation we can go crazy with the spine and not be bound by realistic limitations, but that's not what I'm analyzing today.
So, I'm considering X, Y, and Z rotations just like they are used in Maya: rotate X is rotation around the X axis, meaning mostly a bend backwards or forwards, rotate Y is basically the twist, and rotate Z rotates around the depth axis, meaning visually left-to-right rotations. Rotate Z is usually the easiest to understand. Some rotations here and there are less obvious, because of the camera angle, I'll explain later on.
One observation before we get started - the chest is a massive block, the spine starts bending immediately below it. The hip area is another, smaller block that doesn't bend (although the muscles, fat & skin (and clothing) do stretch over the rigid skeleton underneath, giving these blocks a not-so-rigid appearance). Some cartoony characters might be built to bend 100% all the way up and down, from neck to the base of the hips, but that's not what happens with real humans.
My victim is a pretty famous actress (she's pretty too. and famous. so there you go...). OK, she's dressed, so it's hard to tell sometimes exactly what's what, but I already said I'm doing some guesswork... following this post will be another one with nudes, where things will be clearer (although these things are never too easy or obvious anyway). Maybe I should do an analysis of nudes first and this post should be second, but eh. And to quote Forest Gump - that's all I had to say about that. Let's get started.
Pose 1
Notice I also added a green Center of Gravity bonus. I made it start from inside the upper-chest (I don't think it should be calculated starting with the base of the chest, because when the chest rotates, if the upper part goes left, the COG moves left as well, not right, along with the lower part. Not too sure of this, but guess I'm at least in the ballpark.)
Not much to say here, it's a fairly clean pose, the X axis is not much to talk about, nor is it too visible in this angle. Its effect on the pose is also not drastic. To be accurate, we'd need to judge in context - if I'd be analyzing from video it would be easier, because you can see where things come from and where they go. For example, as the chest is rotating from another pose, you can see what it does, relative to that pose.
Now here comes the issue of relativity. Poses are relative! To their neighbors. They exist in absolute space, but it's more important, I think, to get them right in relative space (one joint rotation relative to the rotation of other joints, and one pose relative to other poses). If we can get both spaces to coincide, it's ideal. More about this later.
By the way, when people talk about pushing poses, many times they mean - exaggerate a pose, some people might mean... push for accuracy, create a more accurate pose. I prefer this second meaning of "pushing" a pose. And this article is about trying to get as accurate as possible into understanding a few aspects of posing. I think accuracy is a huge thing, besides other principles of animation - by me, accuracy should be an animation principle ;) .
OK, a little bit about the Y and Z rotations - how do you tell in absence of other frames/poses what exactly happens. Because while it's easy to see what the limbs are doing, the hips and chest... are hard. My best answers for now would be:
1. stand up (or sit down, etc) and try it for yourself, to better understand the pose.
2. look at the limbs and what they are doing, their position is often a result of what the chest and hips are doing. For ex., here she has her left foot slightly behind the right foot, so that helps us seeing the hips rotating towards left (again, try the pose on your own and see that, in a relaxed pose, you wouldn't have the hips rotating backwards from this - meaning left hip goes with left leg and right with right.) Same, the arms show what the chest is doing.
3. use your common sense - the spine in this pose does look twisted, right? Important thing to know! And then... on to deciding what twists in what direction.
4. use your knowledge of anatomy and, hehe, body mechanics, as much as you can. This is a topic I seriously need to read more about.
Pose 2
Really hard to see what the hips are doing, but I'll be using my phenomenal guessing talents... basically, let's put it logically: she is sitting, so the Z rotation (meaning in fact the X axis - in yellow) is flat, or almost flat, parallel to the ground. But because of the camera angle, it looks rotated. Relativity!
The chest's Z rotation is... well, I might be wrong here, maybe it's backwards from what I've drawn. What we know is that she definitely supports some of her upper-body weight on her right leg. That should mean the right shoulder would normally be pushed upwards, and the relaxed left shoulder is left hanging loose. BUT! One problem with this pose is that she probably is leaning against the wall a little - that affects the weight distribution and the balance of the entire pose. So if the right shoulder leans more against the wall, it's then not pushed upwards by the arm.... so much... and the Z rotation I've drawn is correct. In context (video) I'd be able to tell better, but from a still... I just find it harder. It's a cool exercise nevertheless :)
The rest is fairly basic.
Pose 3
Even harder to tell what's going on without having full feet, but logically, she is placing her weight on her left leg, so the hips rotate as shown... X rotation is again obscure.
Chest rotation is - well, it seems straight, right? But relative to the hips, hehe, there is an angle. It's really hard to determine if the chest rotates more to the right or left... what do you think? (anyway, in this case, it's not so vital... I think... like... who cares? Or maybe, should we care...?)
Pose 4
See how the camera angle makes things hard to read... What's the chest Z rotation? Seems flat. The Y rotation is also obscure, but for the hips, based on feet position, I've deduced the above drawing... The thing is that in subtle poses like this, you might look at it and think you understand what's going on, but be wrong, and look at it from a different angle... and again it looks like it makes sense... but you might again be wrong. But if you can see the movement in context, it's easier. One question for this pose would be - is it static? Maybe. Logically - yes. She is posing. But what if she is captured during a move? That changes things - the balance changes if the pose is dynamic, if she's during a weight shift for example.
Pose 5
Again, we can't see the legs. The clothing also makes things hard to read. But luckily the pose is quite strong. She has her weight on her left foot, but is the right foot in front of the left? Possibly.
In that case, the hips blue arrow should be the other way around. But to me it looks like it rotates as shown. Might be an illusion. Anyway, the fact is that the chest, relative to the hips, is creating a twist, and the chest Y rotation is more obvious (we do see the hands).
Pose 6
The twist is obvious here (but do notice how the hands are working against the body twist), but the Z rotation not so much. Notice how the COG line starts inside the chest. No obvious X rotations, very subtle... maybe the chest is rotating towards the back a little.
Pose 7
This is a cool one. The chest tries to balance the pose by going against the hips. The line of action of this pose would be round along the spine, right? The pose looks simply... round... but in fact, because the chest is rotated the other way from the hips, we have an S shape, not an inverted C. The hips Z rotation could be sort of... flat, but I think it's actually leaning a little towards her right.
Pose 8
OK, completely obscure hips, except for the X rotation which is really clear. The chest is clearer - there may be a little forwards X rotation, and the Z rotation is not vital here, I guess... Very subtle anyway, and hard to see from this angle. Cool pose, hihi.
Pose 9
OK, she's sitting, so that means the hips are flat against that surface. All the weight is there, although there might be a little of the chest's weight on the hands too, not sure exactly how much. The X rotation, if there is any, is subtle. The Z also, it could actually be the other way around.
Pose 10
Oh, yeah, this is not Calista. Ooops. Ammm, too late now... hehe.
But do notice how on a fairly undressed body things read much clearer - even in the absence of the feet contacts.
So why did I do this analysis on Calista, why not on naked bodies with complete poses?? For fun :D and... also, I think I learned some things, because I had to struggle to understand what was hidden. But for fun, mainly! You can't argue with that :D
That's it for now. If anyone thinks I'm wrong with stuff, please post and let's debate it.