Maya Graph Editor Animating Problem

#1

Hello,

I am animating a human character in maya 2010 OS X. The legs have an IK system. I am trying to get his foot to stay in one spot as he runs so he doesnt look like he is moonwalking, so I open the graph editor. Character is moving in Translate Z, I select the handle controlling that foot and in the graph editor change the Z translate for frames 12 and 24 (1 step in my walk cycle) to the value that is at frame 1. This usually works however even after I edit in the graph editor that characters foot still moves with the rest of the character and does not stay planted. The translates for each frame even show that there is no movement, translate Z has the same numeric value even tho the foot is clearly moving along the z axis. This is driving me crazy! If anybody knows what to do I would really appreciate it! Have already tried restarting maya.

#2

It’s a bit hard to diagnose without seeing the scene myself, but my guess is the hierarchy. Are the legs following world space, or the body? If you drag the body around do the feet stay in the same place? If not, then that could be why your character appears to be ‘moonwalking’.

#3

Have you checked if the parent of the foot controller is animated as well? You could have been animating the root or parent controller for the foot.

#4

Ok I’ll try and explain the best way I can, I am new to animating in maya sorry if it sounds unclear. I have all joints of the character under a character set, so yea the joint is definately being animated. I have been manually selecting each frame, then the ankle, and keying the location over and over again, its been horribly frustrating. I have been using that method because the graph editor is unresponsive to any changes I make, I set the translation Z line to a straight line (no change in value) but the ankle still moves. Even if I manually enter the translations of Z for every key, the ankle still moves! It is really bizarre and I dont know what to do. I don’t want to keep having to key the ankle literally every frame and would rather get the graph editor working, because at this rate it will take forever to get a run cycle going. Could this be a problem with the rig or something? The rig functions perfect when keying every joint, every frame…but obviously that would take a horribly long time! Any help would be awesome, I hope I explained well enough. If anybody wants me to post a small vid showing the problem I could do that as well. Thanks.

#5

By the way, I am a little confused what you mean by the root or the parent. This is the rig : I have two nurb curbs controlling the ankles and knees, which is setup using an IK rig. The IK rig connects to the root joint, (his hip joint) and then everything on top is FK. Then I have another nurb curb controlling his hip and selects everything from the hip up. Then I have a bigger nurb curb at the bottom of the rig that selects the whole rig and geometry. So When I animate the character, I select the frame, the character set button I made (selects all the joints) and then I key the movements. I have been currently selecting just the nurb curb (that selects the ankle) that needs to be on the ground and keying every frame for the foot not to move due to the problem I am having with the graph editor not responding…

#6

You generally don’t want to be animating joints directly, especially in the case of your leg setup with IK. You should also avoid placing joints that have IK in a character set. You’d want to only keyframe the parent of your ik handle and not the joints to that leg setup at the same time. This is probably where your problem lies. The entire point of the ik is so that you don’t have to manually keyframe the joints in that chain.

In your case, you should probably remove the leg joints from your character set. Also remove any animation keys on it. It should be fine to leave the rest of your character’s joints in the set if you aren’t controlling them with another controller. It isn’t bad to animate joints directly, but using curves to control joints makes it clear to an animator where a character should be animated.

#7

I think there are some gaps in your understanding of how animating an IK limb works.

When using IK it’s typical to animate control objects (usually a foot controller to determine where the foot is placed and a pole vector controller to determine where the knee is pointed).
As mentioned above you generally don’t key the joints when doing this.
The reason you don’t see the Z translation for the foot changing in the timeline is because its local translation never changes, it’s a child of the knee joint usually and doesn’t change its position relative to that (unless using a stretchy IK rig, but that’s a little different). When using an IK rig you are only effecting the rotation of the leg joints, not their position usually.

So my advice would be to only key the control objects for your rig, unless you are animating rotations of limbs in FK, generally though IK is easier to work with for legs unless your character spends a lot of time off the ground during the animation.

Another thing to consider with this is the hierarchy of the control objects. Most rigs have a ‘root’ mover control, sometimes called the layout node. This is the top most control in the hierarchy and has all of the other controllers as children of it. Generally this controler is used to place the character in your scene and then the other controls , body, legs etc are used to animate the character moving around from that point on. However - sometimes people animate walkcycles ‘in place’, ie treadmill style and then use the main mover to translate the character around to make the looped cycle move through space. This is common for game animation, not so much for feature animation. The problem with this though is that it’s easy to get caught by the fact that when you move the main mover all of the other controls move with it, even though their local coordinates don’t change (the values in the timeline are local so you won’t see them change for the feet when moving the root control). There are ways around it (making sure the keys for the feet are linear when they are planted) but generally it’s just better to not animate that root control unless you really want to reuse a cycled run or walk.

Hope that helps,
Cheers,
Brian

#8

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