Horse animation

[Rasheed]

I could perfect my walk animation of two-legged creatures, but because two-legged creatures are so familiar to us humans, I thought I should attempt animating four-legged creatures instead.

My first naive attempt was this animation:



The legs move somewhat like a horse, but not really.

To rid myself of the confusion of realism, I roughly traced a photograph of a horse, downloaded from the Internet, as blocks and used that for the character to animate:



I'm sure it's not anatomically correct, but it will do for now. I've read somewhere, that a walking horse is like two people walking behind each other out of sync. While the first person is in the contact position (both feet just touching the ground), the second person is in the passing position, or breakdown position (where one foot passes the other, load-bearing foot, from behind). So this lead to this animation:



The horse walking right to left is the more primitive form, while the horse walking left to right is more refined, and walks more horse-like.

I guess I have to study the gait of horses in both Richard Williams' Animator's Survival Kit and Eadweard Muybridge's Animals In Motion. Next, I should have a look at some real horses at the local manege (riding school).

Studying the anatomy will also teach me how to best rig a horse.

[synthsin75]

Very nice for a first effort! The refined (left to right) looks pretty good. The only thing I'd change is that the rear legs seem to kinda stick a bit after they leave the ground. Maybe release the bone locking a bit earlier, if that's how you did it.

But overall, very nice looking walk.

[Rasheed]

@synthsin75: I didn't use any bone locking.

Here is a further development, after studying the mentioned books.



I don't yet fully understand the basics, but there is some progression. I traced an image of a skeleton from Wikipedia, and used that for shape of the parts of the horse and the placement of the bones.

The head and tail don't move, and the shape of especially the hind legs is just bad. I guess I need to rethink my setup.

I also need to study some more. The animation is really though. Perhaps I should do the animation of the hind legs and the front legs separately and join them afterwards.

The problem is that parts of the horse are moving back and forth, up and down, and rotates along the Y-axis (axis through the hips and axis through the shoulders). This means the perspective of the backside changes, as well as the perspective of the chest area and the head. I need to figure out how to draw this in Anime Studio.

[synthsin75]

I think the back legs look pretty good there, movement and shape. I'd probably point bind some of the flank muscle to the body so the whole thing doesn't rotate with the leg.

It looks like there may be too much shoulder motion in the front legs. They seem a bit detached.

Better and better. At this rate you'll have it mastered in a couple of days. I wish my progress went as fast.

[Rasheed]

@synthsin75: I don't know about mastering it within a couple of day, but thanks anyway.

Here's some theory. I've taken the formal definitions from the book Animals in Motion.

Important concepts are "step" and "stride":

• A "step" is an act of progressive motion, in which one of the supporting members of the body is lifted from the ground, thrust in the direction of the movement, placed again on the ground, and caused to reassume, either wholly or in part, its proper functions of supporting and propelling the body.
• A "stride" is a combination of actions in progressive motion, which requires each one of supporting members of the body, in the exercise of its individual functions, to be --either alone or in association with another supporting members-- lifted from the ground in its regular sequence, thrust in the direction of the movement, placed again on the ground, and caused to resume the same relative position to the body and to the other limbs as it occupied at the commencement of the motion.

In humans, walking on two legs (i.e. bipeds), a stride consist of two steps (left foot, right foot). In four-legged animals (quadrupeds), a stride consists of four steps.

Keeping track of four legs can be a bit confusing. To help understand how a stride is performed, in each stage of the stride we can draw a diagram that shows which of the supporting members is touching the ground. The diagram also shows the direction of the movement, and numbering, to indicate the sequence of the stages (1-2-3-4-5-6-7-8-1...).

These symbols are used (left and right is observed looking at the back --anterior-- of the animal):

left hind leg
right hind leg
left fore leg
right fore leg

If all four legs are on the floor, this would be notated as follows:



The diagram doesn't tell you anything about the exact position of each part of the body in that stage, just if a member touches the ground, or not. In animation terms, it is a timing diagram. You still need to figure out the spacing and secondary actions.

Note that while humans only have four possible stages in their timing diagrams (two feet, left foot, right foot, no feet), quadrupeds have sixteen possible combinations of whether or not supporting members touch the ground.

In the above animation, I used a reference of a walk from Animals in Motion (page 28) and the next diagram (page 30).



This walk consists of eight stages. Stages 1 through 4 are left/right mirrors of stages 5 through 8. For instance, stage 5 is the left/right mirror of stage 1. This means that it is enough to have exact reference material of stages 1 through 4, because it is possible to construct the other stages by mirroring left and right.

If you check the timing diagram carefully, you'll see that each supporting member is on the ground in 5 of the 8 stages. This means the legs leave the ground only momentarily and while they do, they accelerate and decelerate. This calls for cushioning of the leg movements while they're in the air. It also means the legs move faster forwards through the air, than backwards on the ground. That seems reasonable, because propelling the body requires more force than moving a limb through the air. Air is also offers less resistance than terra firma.

It is all logical, if you start thinking about it. I guess it is this logic you're after, and you will need it to portray a walking horse in animation somewhat realistically. When you know how to do a natural walk, you can get imaginative and do all kinds of entertaining stuff to offer more bang for viewer's bucks.

Another logical conclusion is, that in order to move a limb forward, either the hips (for hind legs) or shoulders (for front legs) need to turn. This means that, while walking, the back and front of the body turn along the vertical Y-axis, in a kind of wiggling fashion, as seen from above. This means both the base of the tail and the neck move sideways during the walk. This causes all kinds of secondary actions in the tip of the tail (passive) and the head (active). The tail will swing left and right. The head will up and down and tilt a little, to counteract (and dampen) the movement caused by the swaying of the shoulders.

[GardenGuy]

Awhile back I traced several frames of a horse trotting from real photos taken in sequence that I found on the internet. For my scene everything is in silhouette but you can see the movement of body tail head and legs of the horse. (it made a difference to have all of those move a little from frame to frame). I set the separate layers (frames) up in a switch layer using the same # of points so I could interpolate if I wanted to.

You can see a short video of what I did. It is the mov called Horse and Sleigh in the snow.mov at:

www.gardenguy.keepandshare.com

[chucky]

Rasheed, I have a little suggestion. If you have drawn all of the horses vector shapes on the same layer the you could bind some of the shoulder and hip's control points to the spine bones to stop them floating around.
I think maybe you could loosen up your approach?:) All this analysis is great, but if you got into the spirit of the horses movement a little more instead. Get that head neck and spine moving and note how the horse moves in bursts of acceleration that forces its bulk forward against the forces that would keep it still.
I much prefer the second horses than the third one for the freshness factor, hasn't GreyKid done some awesome horse work?

[Rasheed]

I think I should study real horses, to get a fresh look at the matter. However, I needed a simple method for the timing, hence the theory.

I guess once I have a solid set of drawings, animating the stuff in vector animation will become much easier. However, I realize, that even for a professional animator who has never done horse animation, it may take months of study to get it right, to get believable horse animation, beyond the tracing of stock video.

And to quote Brad Bird (I recently had to do that for another forum):

But the things is that guys who invented this stuff hadn't anything to look off. So where did they go to figure it out? They looked at their uncle Lou. They looked at films. They looked at paintings. They drew from animals. Their own observations. So life was brought into animation and it felt fresh. So I really try to urge my animators, and this is something that Pixar does all the time as well, to pull from life, to pull from themselves, and pull from things that they observed. And don't look at animation, because it is like eating your own tail.

So, I won't look at animation as an example how to do animation.

[chucky]

I do agree with looking at proper reference of real horses, but don't just look at the legs, look at the whole horse, maybe blur your eyes and look for those lines of action. There's no harm in seeing how another animator approaches these things, you might have a totally different idea of how to exaggerate ( or not) aspects of the subjects character and movement.
I do not profess to be an expert in these matters, but I thought you might appreciate a slightly less technical input.
I Look forward to seeing your horse coming to life.

[Rasheed]

I know I tend to over-complicate things, but this forum usually keeps me on the right track.

You're right that I should first concentrate on the overall movement of the animal's body, and then see how this relates to the parts, how the masses move, and why. Once I have that I figured out, I can perhaps extract some of those observations and put it into a horse animation.

I don't want a realistic horse animation, but rather more like a cartoon, cute and cuddly, which let's you go "Ohhh."

[jahnocli]

There was a French cartoon series, "Lucky Luke" -- he had a funny-looking horse. Maybe you could try tracking down a DVD, or search the web for some pics as reference...

[Rasheed]

I know Jolly Jumper.

[synthsin75]

Great timing reference you've found there Rasheed.

[Rasheed]

Wondering how to create moving masses in Anime Studio, I created this male cheast animation, using actions. Well, I created the points animation first, and converted that into actions for easy animation.



The point is that the front and back of the horse is turning slightly left and right around an axis paralell to the Y-axis, and through the hips and shoulders of the horse.

The animation is still a bit rough, but it demonstrates the principle. The volume is created by a combination of shapes slightly sticking out of the shape underneath and differences in line width. As you can see, it is easy to spoil the illusion of 3D. I'm sure if you'd add 3D shading, the illusion would get much better.

[synthsin75]

http://www.mediafire.com/?sjkgi4firnh

Something like this Rasheed? I just threw this together real quick. Let me know if it helps any.

Doing something like this, you can do away with the flanks you have as part of your legs.