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Question Facial animations: Jaw bone giving me trouble with blend shapes. Avoiding double motion

Discussion in 'General Discussion' started by dgoyette, Oct 22, 2022.

  1. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
    Posts:
    3,998
    I have a character model that has a jaw bone along with blend shapes for facial expressions. If I move/rotate the jaw bone, the face's mech goes with it:

    upload_2022-10-22_13-53-17.png

    The mesh also has blend shapes. Here's the mouth opening via blend shape, without rotating the raw:

    upload_2022-10-22_13-54-17.png

    This blend shape doesn't look great on its own, because it doesn't move the jaw/teeth. So, it seems I need to both move/rotate the jaw and adjust the blend shape. However, because moving the jaw also affects the mesh, it ends up kind of doubling how much the facial mesh gets moved:

    upload_2022-10-22_13-57-6.png

    These blend shapes appear to be the default provided by Character Creator characters, so I don't think they were rigged "wrong". But I'm not sure how I can effective animate the character talking. I can't just move the jaw, since the lip sync software I'm using uses blend shapes. But I can't just use blend shapes, since the teeth with remain completely still.

    Does anyone have experience with rigged models using blend shapes as well as a jaw bone, and getting these to play nicely together?
     
  2. Jmonroe

    Jmonroe

    Joined:
    Jul 7, 2012
    Posts:
    117
    I believe the facial animation [at least from iclone] works by combining the jaw movement with the blendshapes. I have facial animations working on Character Creator characters, but I had to create a 2nd layer in the animator with an Avatar Mask applied to the head only, and blending set to override. Again, this is for a Humanoid character playing facial animations exported from iclone.

    I would think a lip sync software would use a similar setup, but the authors of the software would know best.
     
  3. dgoyette

    dgoyette

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    Jul 1, 2016
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    That makes sense. But I guess that only works if whatever recorded the animations was also recording the jaw rotation/position change. In my case, all I'm getting is blendshape values.

    I ended up realizing that I could just create blend shapes for the lower jaw itself. So, when the face's Mouth_Open blend shape is used, I'm also setting the jaw's Mouth_Open blend shape as well. This just moves the verts of the jaw, it doesn't rotate the jaw bone, so I don't end up with the double accounting on the face mesh. This feels a little cludgey, but in my case I don't have an easy way to recording the jaw position/rotation into my clips, so this will have to do.
     
    Jmonroe likes this.
  4. dgoyette

    dgoyette

    Joined:
    Jul 1, 2016
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    3,998
    In case anyone else runs into this (and so I don't forget how I did this in the future...) I made a quick video on how to get the jaw bone transforms to be incorporated into the shape keys. The end result is that the jaw can fully open just using shape keys, without the need for any extra code to move the jaw bone itself.

     
    Jmonroe likes this.