Facial Animation with Maya Blend Shapes - Art 173a  

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Note the assignment choices are at the end. Check them out before you begin.

You will learn how blendshape was used by Chris Landreth to create the facial expressions for the Balloon Girl character in his animated short, Bingo.

   STEP ONE

Download the project file: blendShapeStart.ma

This file includes a different face that uses the same surface topology (number of CVs) and the same facial poses as Balloon girl.

In the center of the screen you can see the base version of the head. Around the border are 16 different versions of the head.  Each of the heads contains one facial muscle fully flexed.

   STEP TWO

Open the Outliner window and expand the node facialMuscles.

When creating a blendshape, the base shape needs to be selected last.

  • With LMB drag select the nodes from OpenJaw to SquintRight.
  • Press Shift, then select BaseHead.

With the shapes selected, a Blendshape can be created by selecting Deform > Create Blend Shape.

The facial expressions are no longer needed and can be hidden by hiding the Facial Poses layer from the Layer Editor.

   STEP THREE

Open the Blend shape window by selecting Window > Animation Editors > Blend Shape...

You now have full control over the character's expressions because you have the ability to flex any of the facial muscles by simply dragging a slider. 

Experiment with different settings and combinations of poses. You can either use the sliders to blend from 0 to 1 or you can type in a value. One important feature is that you can type a value bigger than 1 or smaller than 0 to get exaggerated effects.

If you are not happy with any of the original poses, it is possible to go back and edit the pose shapes. This only works if you have maintained history for the blendShape node.

TIP: By default, Maya will create the sliders in a vertical direction. You can align the sliders in a horizontal direction by selecting Options > Orientation > Horizontal.

   STEP FOUR

You now have the basic controls to create a variety of facial poses. But, for lip-synching, having this many controls to keyframe could be very time consuming. One possibility for creating a higher level of control is to use Set Driven Key to create a set of sound shapes (phonemes).

The control for the Set Driven Key will be connected to a locator next to the face.

  • Select Create > Locator.
  • Move the locator beside the girl's face.
  • Make all the default channels non-keyable for the locator by selecting Window > General Editors > Channel Control...

 STEP FIVE

The next step is to add the phoneme attribute to the locator. You will create an attribute for the "SH" sound.

  • Select the locator.
  • Select Modify > Add Attribute... and set as shown in the adjacent figure.

The SH attribute now appears in the channel box. This attribute exists but it is not yet functional. Set Driven Key will be used to create a relationship between the blend shapes that make up the "sh" sound and a value for it.

   STEP SIX

Before using Set Driven Key, you must set up the pose for the "SH" sound. In the Blend Shape window, set the following:

  • Open Jaw to .15
  • Lower Lip to .75
  • Purser to .6
  • Sneer Left to .25
  • Sneer Right to .25
  • Note: You can also enter these values in the Channel Box if the Blend Shape node is selected by pressing Select in the bottom left hand corner of the blend shape window.

       STEP SEVEN

    You will now set up Set Driven Key with the sh attribute set to 10 when the mouth is in full "SH" shape.

    • Select Animate > Set Driven Key > Set - option
    • Select the locator.
    • In the Set Driven Key window, press Load Driver.
    • Select the Blend Shape node (press Select bottom left corner of Blend shape window)
    • In the Set Driven Key window, press Load Driven.
    • Highlight SH in the right column of the Driver.
    • Highlight holding ctrl, OpenJaw, LowerLip, Purser, SneerLeft, SneerRight in the right column of the Driven.
    • Enter a value of 10 for the SH attribute in the channel box.
    • In the Set Driven Key window press Key.

    You will now set up Set Driven Key with the sh attribute set to 0 when the mouth is in neutral position.

    • Change the SH value to 0.
    • Press Reset All in the Blend Shape window.
    • Press Key in the SDK window.

    The sh attribute now has a range of 0 - 10 which can be keyframed.

       STEP EIGHT

    You have now learned how to create blend shapes using various facial poses then incorporate Set Driven Key to set up a higher level of control for lip-synching.

    Assignment - Choice one or more(any order):

    1) Do the same steps to create all the lip sync phonemes. Use this phoneme guide to help you.

    2) Using this Set Driven Key technique, create high level expressions. Use the lecture notes on expressions as a guide.

    3) Create an emotional animated short movie (like what we did for the first assignment with Ken Perlin's system).

    4) Create an aesthetic texture for this character.