Inspired 3D: Subdivision Modeling Techniques (continued from page 3)

Figure 17 and 18 show some of the progression from long hair to the relatively clean-cut look.

[Figures 17, 18] The first hair proposal (left) and the final hair.
The eyes were built from three NURBS spheres nested inside each other: A clear outer layer (the cornea). This layer is simply a clear reflective ball that surrounds the rest of the eye.
  • A colored interior layer (the iris). This layer has a recessed, or concave, area around the color of the iris that reacts to light. When light is directed above the eye, the iris will have additional reflection that occurs beneath the pupil. This anatomy is physiologically incorrect, but this lighting has become an accepted way that eyes appear in computer-generated characters. The characters in the Pixar films and the PDI films have their eyes constructed in a similar manner. The opening for the pupil is simply a hole that has a cluster that controls the diameter of the hole. This allows for animation of the size of the pupil.
  • A black inner layer (the pupil). This layer is adapted to fit the iris. The shader on this layer is a black surface shader that emits no light whatsoever.

    [Figure 19] A close-up of the eye reveals some of the way the eye was built.
    Teeth, Gums and Tongue
    These were simple models. The teeth are simple NURBS spheres that have been flattened to resemble teeth, and the gums are surfaces that have been sculpted to accept the simple teeth.

    The tongue is a half sphere that has been modified to resemble a tongue. All of these items are NURBS construction because this type of model is relatively easy to create, map, and animate. Even though these parts are important, the focus of this chapter does not need to cover this material.

    Facial Animation and Blend Shapes
    In the production of an animated character, the character can have the face animated in two basic ways. One way is to have animation setup control the face using various setup techniques. This requires expertise on the part of the setup technical directors. In a large production facility, the efficiency of scale can make difficult jobs like this commonplace. Many characters have already been set up that can be taken apart and reused. In a small production, the process of creating facial controls can be time consuming. This is especially true because no other similar characters can have their controls “recycled” for the new character.

    On this production, despite my best efforts to avoid this, the production decided early on that the facial animation would be controlled using blend shapes. Blend shapes are 3D morph targets that have the exact topology as the face they are controlling.

    Full Face Shapes versus Local Face Shapes
    In the creation of face shapes for an animated character, there are two basic schools of thought regarding the way the face should be animated using blend shapes. One method is to use the entire face as a specific target. If the character is going to frown, then the entire face is sculpted into a frown shape. The eyebrows are sculpted into a furrowed appearance, and the entire mouth is sculpted into a real scowl.

    Face targets like this are normally sculpted to the maximum range, which can be used as the production dictates. If the shape is a 100% frown, then the production can use this shape in increments of 20%, 40% and so on, to create frowns of less intensity.

    Local face shapes are broken down into specific regions. These into left, right and center regions. If there was a smile to be modeled, the blend shape would be a left smile, a right smile and a center smile. This gives the animator a lot of control as to what part of the face will be affected by the blend shape.

    For this project, the local blend shapes were a necessity. But because I know that the vast majority of animation time using blend shapes was spent trying to get multiple blend shapes to animate as a single channel, I also added some blend shapes that took up an entire region. I modeled a left smile and a right smile, and I also modeled an overall smile as well. I modeled a left furrowed brow and a right furrowed brow, and I modeled an overall furrowed brow.

    The jaw was to be animated using a skeletal setup. The jaw position is not animated using blend shapes. The modeling of the blend shapes had to be coordinated with the animation of the jaw. The figures below show the jaw in various stages of being opened or shut along with the blend shapes being shown. This helped visualize how the blend shapes would behave during the modeling process.

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