Why does the mesh deform when scrolling through the timeline?

[Sev1x]

A part of a character's mesh deforms when I scroll through the timeline and I'm not sure why. I added a scaling and parent constraint to the the upper body and the stomach area to animate breathing, so that may be the cause. The weight influence in the areas seems to be okay. A clarification would be appreciated.

[stephenkmann]

I'm not sure what's doing on with this rig.. but the reason you are seeing the movement is that the skin is bound to the joints. that are animated.

There is also some sort of cycle on the center of the spine.. if you scrub, for some reason it keeps spinning and spinning. *( this is a sign that there is a  cycle on the rig, and its not calculating correctly)

Out of curiosity, what version of maya did you create this in ?  

-=s

[stephenkmann · Accepted solution]

 The Problem with the spine, seems to be that you have parent and scale constrained the last joint of the spine..

gemini:Spine_05_Jnt

I would replace that parent constraint with a rotate constraint.. 

The spline IK is already moving that joint, so the parent constraint it conflicting with that and causing cycle issues

hth

-=s

[Sev1x]

The parent constraint was there so the chest could be translated up during breathing, so which constraint or other method can I use to do that without conflicting with something else?

[stephenkmann]

the SplineIk will already move the spine joint chain. 

you can move that control. but often I'll orient constraint that last joint to the control as well.

if you want to make the spine stretch. you can connect the length of the curve to the translate or scale of the joints in the joint chain

I made a quick video showing how to do that...

https://youtu.be/KmnynMhcrIA

hth

-=s

[Sev1x]

Have no need of stretching the spine at the moment, but might be something that could be useful another time.

[stephenkmann]

you said you want to "translate" the chest. 

so.. you can make a stretchy spine. 

or add another joint and parent constrain that to your control

hth

-s

[Sev1x]

I can't make changes to the IK spline because that will cause problems when the character have been moved to Unity, so I'll settle for rotating the clavicles.