Quick Trick: Feet First

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.

So...

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.

The Power of Pyramids

First off, sorry its been so long since I posted anything. I don't intend on letting this blog sit and rot... I've just been super busy with work and my little boy. I have a small scale animation that I'm working on ( not the vampire thing right now ) and I want to post a detailed breakdown of the process - should be a cool post I hope, so keep watching.


The power of pyramids ? whats he talking about ?

I've been wanting to write a post about this for a while. Its something that I think about, and use, every day when animating - but to be completely honest I don't fully understand it, so this post will serve as an exploration of this idea, rather than a hard set 'technique'. Bear with me as I try and clarify this in my own mind too... ;) I will try and keep all observations at objective as possible.

Ok... so I'm sure we've all heard of "poses" and "lines of action" and their massive importance in animation, but something that I like to include in my thinking is the idea of creating solid shapes.
There is a very common shape that we all use often - the curve. Its nice to contrast between backwards and forwards curves in our poses, and also straight against curve. I love these tools, but really I don't so much regard them as shapes. To me they are still lines ( but not necessarily "lines of action") .

I use a particular shape over and over, and it repeatedly helps me define strong poses and dynamic shapes.... the pyramid.

So check out this image below. I'm sure you've seen it once or twice before...



Something strikes me about the pyramids. Ignoring all the stone, and the sheer scale of these things - the shape itself says a lot about weight, stability, pressure and origin ( or direction ).
the tips of the pyramids look light and are supported high by the wide bases that seem firmly planted on the ground. You can see the "direction" of the weight, i.e, it becomes heavier as it approaches the ground, and the heaviest part of the pyramid is right at the bottom. A single 2D pyramid also has two straight lines that contrast against each other in their direction of travel. They also have a built in way of naturally leading the eye to a particular point, at the tip of the pyramid.

If we look at pyramids of different proportions - it seems the same ideas still ring true, but with varying strengths (i.e the tall thin pyramid still has the same 'feeling', but the short wide pyramid feels much more weighty and planted to the ground )




If the pyramid is turned upside down... something interesting happens. It seems as if the point of contact on the ground is an area of high pressure, supporting a strong weight above it. The shape of the inverse pyramid points downwards and amplifies this pressure. There is also a strong sense of balance and equilibrium when the pyramid is seen this way around.




It also seems that the pyramid can be distorted - yet still retain the same visual ideas.




So, there seems to be a subliminal strength associated with the pyramid... and we can tap into that shape, and use it in our poses.


Application to posing characters, and its effects...

Below I have taken a number of images from around the net that I feel illustrate this idea in different ways. They all use some kind of pyramid shape, that helps to strengthen the attitude of the character ( click on the images to view them more clearly ).



The blue pyramid shows the direction of the wolfs attitude, and places his weight back behind his head, and plants his overall shape firmly on the ground. In a sense it summarises the broad pose. The red pyramid shows the pressure exerted on the small paws of the wolf, at the point at which they meet the floor - illustrating the weight of the creature, and the energy needed to counter the weight as it travels up into the chest and shoulders. The red pyramid also suggests a feeling of careful balance, inertia and poise - that lends a certain natural anticipation to this image.




I can only really see one pyramid in this image - but I think that's reflective of the power and straight forward nature of this pose. The pyramid plants the characters feet and weight firmly on the ground, and the edges lead our eye to the point of interest - the hand that is delivering the force of the blow.




The blue pyramid describes the weight of the character - and the direction of the attitude - the tip also leads our eye towards his face. The red pyramid is the interesting one in this example - the bottom tip ( at his elbow ) shows the point of pressure as the character leans his body weight to be supported by the chair. His upper arm creates one side of the pyramid - but contrasts a little oddly with the relatively straight edge that runs up his forearm.. is this why he seems a little off balance ? like hes not quite leaning on his elbow ? almost as if his pose is a little forced ? maybe I'm being too subjective now.




In this instance the red pyramid describes the broad attitude, and leads the viewer towards the left foot, which is also the point of pressure as the character bears down her weight to take the next step. On its own, the red pyramid is a little off balance, and by itself it would seem as if she might fall backwards. The blue pyramid solves this problem by grounding her weight between both legs, and providing support for the tall pose.




These images are interesting in comparison because the top red pyramid seems to describe a pose that is off balance. Despite the fact that the character's feet are firmly planted on the chair, all the pressure is concentrated in the small area of her feet, and there seems to be no blue pyramid to provide any grounded support. The red pyramid also seems to be off balance - making the overall pose seem tall, un-centered and looks almost as if she may fall at any moment.
In contrast, the second set of images has a strong blue pyramid. despite the fact that we can't even see the characters feet, we have enough of a strong shape there to show that the pose is firm and stable.




As a last example - this pose is interesting because it seems to have a blue and red pyramid working directly together. The red pyramid shows the downward forces of the body, coming to a high pressure point at the feet, taking all the weight from the hips. This alone could possibly seem off balance, but the upper body pose can be summarized with a blue pyramid that works to produce a harmony. Together the two shapes seem to describe an eloquent balance of forces, that could be used to nicely describe the attitude of the female character.

So I hope its not just me, and these things really are going on in these images. I find it useful to think of these shapes when I animate, because above everything else - they seem to provide a certain approach to the aesthetic stability of the character - but can also add that extra uncertainty or anticipation when the shapes are not balanced, or deliberately jarring.

Keep your eyes open and maybe you'll see some of these... Drop me a mail if you know of any more!

( oh yeah .. and I did realise after a while... they're triangles not pyramids.. but then where would the catchy title be ? ;) )

Quick Trick: A Simple Approach to Overlap

Once we have good story, good poses and all the basics down nice and strong - some good overlapping action ( or "follow-through" or some people occasionally confuse this with"secondary action" ) can really add that beautiful organic movement to our animation. When its easy to animate, it can be a lot of fun, but sometimes it can cause real headaches when we have complex movement, or varying timing.

There is a quick trick that helps you to think about overlap in a structured way. I'm not saying when or where to use it, I just mean the technicalities of where body parts should be at what time, depending on movement. Its only a quick trick and so doesn't by any means create beautifully complex ( or accurate ) overlap, but it does give you a good starting point to work more detail into.

Ok so here's the tip:

This a simple chain of cubes animated with joints ( only the first joint is animated ). There is translation and rotation movement that we will need to figure out the overlap shapes for. ( note this is just a chain of cubes to show the idea clearly, normally we would be doing this on a spine, a head, an arm, a tentacle, a limp body part... anything! you get the idea ):



The basic idea of this tip, and the foundation that makes it all work, is to set keys on the whole chain when it changes direction. So if you look at the video below, I added a motion trail to show you the path of the boxes, and you can clearly see the places where the direction of movement changes. So at these points, I am not setting any poses or changing anything - just simply keying all the joints in the chain in a relativley straight pose. On the section where the chain is "flapping", I am doing the same thing - keying the whole thing when it starts to flap in the other direction. These are the "marker" keys:



Now to start the overlap, all I have to do is to set "drag" poses between the keys I already set. So I am thinking about how much the chain will bend depending on the force, thats all really, and putting this pose half way between the marker keys I set already. You can see that pretty much straight away the effect is starting to look good ( note that in these poses, the whole chain is keyed too, just like a marker pose ):


For the final part we now go and alter our marker keys. The idea is that really they would not be straight at this point, the last few joints in the chain would still be dragging a little. So all I did in this example was added a bit of lag to the last two boxes in the chain, on the marker keys. This adds the final bit of polish. Note that I am not adding any extra keys, all we are working
with are our original marker keys, and any keys we set halfway between each marker key:





A few extra points:

So the best thing about this is the workflow. I spent no more that 10 minutes on this example, and the overlap is clean, fluid and the keys are simple and organized. I also didn't have to get too confused thinking about force and drag, because the marker keys serve as a "reset" point to stop things getting jumbled. Its good to note that what makes this work well is good "halfway drag poses", and careful reposing of the last few joints on the marker keys for the final pass.

This is meant to be a quick method, and is not really applicable for very soft things like cartoony tails or hair - or things that have a lot of drag. However even for these situations it serves as a great starting point. I tend to use this method on torso overlap, head overlap and generally for showing weight across the board. Of course, the amount of softness or overlap is decided by you, and will depend on how carefully you pose your halfway keys and how you modify those marker poses at the end.

Just to mention quickly - the "marker" poses that were straight in this example do not have to be straight in animation. Your character will often be doing an underlying action, and your marker poses will not be straight. The key thing to remember is to key the objects at the point at which they change direction... thats the basis of this idea.

Quick Trick: Push Off !

Well, seeing as this is an animation blog - its about time I posted something up that actually moves. Well here goes. The video link below is a walk I did recently, mosty as a test for a new rig my super talented colleague Goosh is currently working on, but also something that I can use as a good medium to discuss a certain aspect of walk cycles that commonly gets overlooked.


This was really fun to animate. It`s not "true" quadruped locomotion, as it was difficult to accomodate the large stretch of the back legs with the front legs that are shorter and still retain a nice feeling of timing and contact.

First off - this isn`t by a long shot the worlds greatest walk cycle - in fact its pretty run of the mill, but something that I see time and time again in 3D walk cycles is the lack of a good "push off" in the feet, and believe it or not I see it over and over in most CG features.
What I mean is this - as the foot travels backwards in contact with the floor, and begins to get ready to lift up and travel back towards the front, there is a subtle but very important rotation that travels from the ball of the foot and through to the toes. The mechanism for this movement, and the logic behind it, is that the foot tries to retain contact with the ground as long as possible, essentially rolling the foot as far onto the toes as it can go without looking stupid. The body uses more energy to lift the leg through the passing position that it does keeping it planted on the floor.
Many animators overlook this push off, and start to bring the foot back towards the front with hardly any rotation from the toes. It still works, but the feeling of weight and locomotion gets diminished.
We often hear as animators how important it is to show "contacts". This is so true, and good contact poses will be integral to selling a feeling of weight and interactivity with the world. But "push offs" are also contacts - they just happen as the contact is getting broken rather than created.


I've isolated the back legs in this video to clarify this idea ( ignore the repeat frame ). You can see as the foot travels back, there is a pretty large rotation, that travels through the foot, and the toes are still contacted for alost a full 7 frames after the other foot has made its opposite contact plant. OK, this is a pretty stylized ( cartoony ) walk, but the concept still holds very true in more realistic animation.

As a general rule through all my animstion, cycles or not, I try to keep weight bearing contacts planted for as long as possible without looking stupid. It's also generally good to use as least amount of footplant possible to carry out an action, unless the creature's character would dictate otherwise.