Problem with eyes during facial animation

[Slayer89]

I’ve got a model of face, with 4 main joints in it. A base joint, neck joint, head joint, top_head joint. I have the eyes parent constrained to the head joint. For most of the animation the eyes move and stay with the head correctly, however for 4 frames the eyes leave the head move about and go back in. Any ideas what might cause this?

Software used is Maya 2011.

[czacen]

Hi slayer89, your problem sounds rather unique. However what is preventing you from parenting the eyes under the head joint as opposed to parent-constrain?

[Slayer89]

absolutely nothing, except for the same results occuring

[Slayer89]

I've narrowed the issue down the the blendshape that controls the blink. For some reason that blendshape is turning the mesh independently of the joints. So even though the eyes are actually constrained correctly to the joints the movement of the mesh caused them to be outside of the head. The inputs has joints first and blendshapes second.

The original mesh, and the blendshape mesh for the blink are in the exact same position the only difference being the eyelid is closed.

[czacen]

Ah that explains it, the order of your inputs is wrong. Blendshape first and skin second. Swap it and it shld be ok.