Walk cycles, opposing key calculations

Tom Ellis · Mar 2011

Hey guys,

Just getting my head around animating a walk cycle, and I'm having an idiot moment where I can't work out how you'd calculate opposite frames.

What I mean by that, is let's say I'm working on a cycle with 33 frames. For the left foot say, I've got it's extremes at 1/17/33, then the right foot would have opposite values at 1/17/33.

But how do I work out the opposite of other frames, for example, if I have the left arm swing forward at frame 7, what is the equivalent for the right arm on it's forward swing?

Cheers

warby · Mar 2011

(total frame number/2)+ (extreme frame number of left side)

?! right ?! or maybe i am miss understanding your question

Tom Ellis · Mar 2011

Aww man of course that's right, it seems so obvious now!

So if something happens on frame 4, it's frame 20 for the opposite side (4+16).

Thanks man!

Mark Dygert · Mar 2011

When I do walk cycles I do 4 poses for each side, Left contact, Left recoil, Left passing and Left high point, then paste opposite to make the right side poses, Right contact, Right recoil, Right passing, Right High point. which completes the cycle. Here is a really good walk tutorial along with my notes.

http://www.idleworm.com/how/anm/02w/walk1.shtml

Left Contact:

The left heel is touching the ground.
Left leg is mostly straight, toes pointed up, right arm almost all the way forward, left arm almost all the way back.
The right heel has lifted up but the toes still contact.
This is the farthest the feet will be away from each other.

Left recoil:

Left foot flat, normally I put the pivot point in the heel and rotate the foot down.
Both Knees slightly bent as the pelvis comes down to its lowest point, this is where the gravity of the walk is felt, slow lumbering characters normally pause a bit here.
Right toes have just come off the ground and are getting ready to move forward
Pelvis is starting to come up
Arms at the extremes, right arm fully forward, left arm fully back, notice when the left foot is forward the right arm is forward.

Left Passing

The left foot begins to slide along the ground back, a little past the mid point of the character, the heel is still on the ground. I put the pivot in the toes.
The left leg is straight with the heel on the ground.
The pelvis is starting to come up again as it recovers from the recoil and pushes the character up and forward.
The right leg is at the mid point, as well as both of the arms.

Left high point

Pelvis is at its highest point.
Left leg back almost to its extreme, the heel has started to lift.
Right leg forward almost ready for heel contact.

To complete the cycle you make the same poses for the right side. A lot of rigs will have a copy/paste pose feature and most that do have a paste opposite feature which will allow you to invert a pose.

Now how far apart the poses are in the time line is all up to how fast the character will move and what fps you're animating at, but once you have your basic poses in you can scale and stretch them to whatever you need.

Now not every character walks this way and Richard Williams has a lot of interesting break downs of various walk cycles in his book The Animators Survival Kit. It's amazing how much traditional 2D animation factors into 3D so don't think it doesn't apply.

Recommended Reading:
[ame]http://www.amazon.com/Animators-Survival-Kit-Richard-Williams/dp/0571202284[/ame]
"The animators survival kit" is pure gold, super quick read with metric tons of examples.

[ame]http://www.amazon.com/ILLUSION-LIFE-DISNEY-ANIMATION/dp/0786860707[/ame]
"The illusion of life" covers the 12 principles of animation, not all of them effect modern 3D animators, often the ones that pertain to character athletics are out of our control, we just make it move. It's a good read but you can glean the 12 principles from Wikipedia while you're waiting for it to be shipped heh.
http://en.wikipedia.org/wiki/12_basic_principles_of_animation

Tom Ellis · Mar 2011

Thanks Mark, great info and links as per usual!

Ok I gotcha, I'm actually looking at 2D now anyway as it's just quicker and easier to work on my fundamentals without having to worry about a rig. I'll leave the 3D side until I start AM this Summer.

I've got the Richard Williams book, which is awesome, but I'm only a little way into it. I love his way of teaching, although he sure likes to drop a lot of names

I guess that's what happens when you get to work with 99% of the masters of the craft over your career.

I'm curious though, is the DVD version worth the price of entry? From clips I've seen, it kinda looks like a visual transcript of the book. It's very expensive, but I guess if it is really gonna be of great benefit then it might be worth getting it.

Mark Dygert · Mar 2011

I wouldn't abandon 3D, its just that 2D has so much to teach its worth listening to. A lot of 3D guys crap all over the idea of 2D having anything to offer, its an inferior art form, what can analog ever offer the digital world pfftt... Disney... what a waste of my time stupid princesses... "Why can't I find any decent 3D walk cycle tutorials all I find is 2D!? Arrg!!"
Did you try reading the 2D stuff and apply it, it works!

About the DVD, I think the book does a great job of getting it all across, its kind of helpful to see it all moving and watch him act like a nut job but really its mostly a recorded version of his lecture which is preaching pretty much straight from the book. I think the DVD's are more or less a replacement for when he's done doing the live lectures, his legacy of sorts that will live on after he's gone.

I don't agree with everything Richard Williams says and some of it just doesn't translate but the book helped me and just about every animator I've ever talked to, so its worth reading, but once you've read the book the DVD's really don't have that much more to offer, at least not until they come down in price...

Tom Ellis · Mar 2011

Cheers Mark.

Oh I totally agree, even from my position, at the bottom of the ladder so to speak, I can already see how exactly the same fundamentals are equally apparent in 2D. I must admit prior to reading Richards book, I probably would've shrugged off any suggestion to study and 2D animation when I'm aiming to do 3D. But seeing his explanations in examples in 2D has definitely opened my eyes.

I find myself watching old cartoons in a whole other way now, seeing if I can spot how any of the principles and fundamentals have been implemented; arcs and timing etc. And also noticing how there's a lot of new cartoons that seem to disregard them altogether!

Ok the DVD sounds like it might not be necessary, I'll stick with the book.

Thanks again.

mdeforge · Mar 2011

These links should help you immensely

http://pushingposes.blogspot.com/search/label/walk%20cycles
http://www.ewestlund.com/tutorial.html

Walk cycles, opposing key calculations

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