Altering Joint Orientation in Skeleton

Introduction

• Focus on altering orientation of joints in a human arm skeleton.
• Hide geometry as it's unnecessary for this process.

Viewing Local Rotation Axis

• Select Hierarchy:
  • Select shoulder joint.
  • Right-click and choose 'select hierarchy' to select each joint in the chain.
• Display Local Rotation Axes:
  • Navigate to Display > Transform Display > Local Rotation Axes in Maya.
  • Ensures all joints' orientations are visible and consistent.

Fixing Rotation Issues

• Problem:
  • Joints, particularly the wrist, are not rotating as expected around the Z-axis.
  • Need to fix orientation for single-axis rotation.

Adjusting Joint Orientation

• Orient Joints Uniformly:
  • Select shoulder joint, right-click, select hierarchy again.
  • Open Skeleton > Orient Joint options.
  • Primary Axis:
    • Set to X; remain unchanged.
  • Secondary Axis:
    • Choose Z for forward positive orientation.
• Apply Changes:
  • Click 'apply' to change joint orientations.
  • Some joints, like the wrist, still need adjustment.

Correcting Wrist Joint

• Unparent Joints:
  • Select joints from wrist down and press Shift + P (or Edit > Unparent).
• Orient to World:
  • Select wrist joint, use 'orient joint to world'.
  • Ensures alignment with the elbow.
• Reparent Joints:
  • Reselect joints and wrist, press P (or Edit > Parent).
  • Wrist now rotates correctly around Z-axis.

Aligning End Joints

• Use 'orient joint to world' to align end joints in the chain.

Adjusting Thumb Orientation

• Initial Problem:
  • Thumb doesn't curl correctly with fingers when using Z rotation.
• Reorient Thumb:
  • Select top joint of thumb, right-click, select hierarchy.
  • Open Orient Joint options, disable 'orient joint to world'.
  • Set Orientations:
    • Primary axis = X.
    • Secondary axis = Y negative.
  • Apply changes.
  • Ensure end joint oriented correctly with 'orient joint to world'.
• Result:
  • Thumb curls correctly with Z rotation.

Conclusion

• Arm is now correctly oriented.
• Each joint rotates as expected, facilitating accurate animation.