Rigging and Animation
Skeletons and skinning
A joint chain drives deformation. Bind with Smooth Bind or Rigid Bind; smooth bind assigns weighted influences. Paint Skin Weights adjusts influence per vertex. A joint with no influence leaves geometry behind; too many influences cause overshoot. The bind pose is stored, and Go to Bind Pose restores it.
Constraints and controls
Constraints connect transforms: point, orient, parent, aim, and pole vector. Parent constraints are common for props. Controllers are typically separate curves connected via constraints or driven keys. Set Driven Key links one attribute's value to another, useful for corrective shapes.
Animation concepts
Keyframes store attribute values at times. Graph Editor tangents determine interpolation: linear, spline, and stepped. Breakdowns and inbetweens are keys that preserve relative timing. Animation layers add or override motion without editing base curves. Playback and frame rate (24 fps default) affect timing; changing scene frame rate can alter playback.
Traps in exam questions
- Freezing a bound character can break skinning because bind pose data depends on transforms.
- Orient constraint aligns rotation; point moves position; confusing the two is a classic trap.
- Stepped tangents hold a value until the next key, producing a pop rather than a smooth transition.
- Pole vector controls elbow or knee direction; it is a constraint target, not a joint attribute.
Rule of thumb
When deformation looks wrong, test weights before changing the skeleton. When motion looks wrong, inspect tangents before adding keys.
Worked example
An elbow collapses when the arm bends. The joint has excessive influence from a neighboring joint. Painting skin weights to reduce that influence and renormalizing restores volume. Adding an extra key does not fix a weighting problem.