Datasheet
8 Chapter 1: Character Skeletons
Weighting
Quaternion weighting helps skin deformations tremendously. You no longer need addi-
tional bones to help support the volume of skinned parts; you only need to add joints
where your character needs them, making the process far more intuitive.
is also helps with the weighting process. Instead of the skin caving in at a bent joint,
the volume is maintained, causing the skin to penetrate the opposing side. You can coun-
teract the penetration by painting weight from the opposing side. You can even mix the
quaternion weighting with classic linear weighting to have the skin lose some volume in
the area, creating the illusion of collision. Both options create a more lifelike fold in the
deformation. In the rst project, Jack is weighted to his skeleton using quaternion weight-
ing techniques.
Project: Painting Weights
You’ve evaluated the geometry and built the skeleton. Everything is in place for skin
weighting. All of Jack’s weights are done with quaternion weighting. e geometry to be
weighted is one complete mesh. Ultimately, the mesh is divided into two pieces; but it’s
easier to weight a single mesh and then copy the weights to the nal broken-up mesh. e
following tutorial takes you through the entire process.
1. Open the jackWeights_v01.ma scene from the chapter1\scenes folder on the DVD. The
scene contains the character’s geometry as a single mesh and his skeleton. The geom-
etry and skeleton have been assigned to respective layers.
2. Open the Outliner, and Ctrl+select the root_JNT node and the jack node. Choose
Skin
Bind Skin
Smooth Bind tool options.
3. In the default settings, change Skinning Method to Dual Quaternion. Use Figure1.9
to conrm your settings. Click Bind Skin to accept the options.
e default bind does a decent job
of weighting the character. It’s far
from perfect, of course, but it pro-
vides you with a clear path. Most of
the needed corrections center on the
torso. Figure1.10 shows the torso’s
deformations.
4. Select clavicleL_JNT, and rotate it
to –15.0 in the Z. Select shoulderL_
JNT, and rotate it to 45.0 in the Z.
Figure1.9
Change the Smooth Bind options.
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