Design Realization lecture 8

1
Design Realization lecture 8

• John Canny
• 9/18/03

2
Preamble

• Handouts include the Maya bible chapters on
  skeletons and IK.
• First assignment models are due on the swiki
  today.
• New Dell PCs arrived so there will be more
  machines running Maya unlimited.

3
Last Time

• Kinematics skeletons and joint hierarchies.
• Local coordinate systems.
• Inverse kinematics.

4
This time kinematics constraints

• Lets start with the joint-creating tool
• (Animation) ?Skeleton ? Joint tool
• Use default settings
• Draw each joint (front view usually).
• Adjust joint transforms so all moving axes are
  Z axes.
• Recall that X displacement should give link
  length.

5
Binding skin

• Actually very easy.
• Select the skin to be bound, and the top link of
  the joint hierarchy to bind it to.
• Then select
• Skin ? Bind skin
• And choose either rigid or smooth bind.

6
IK and constraints

• IK allows us to position a given joint.
• To control other attributes, we use constraints.
• E.g. we can create a handle which is used as a
  constraint for both position and orientation.

7
Handles

• The goal is to use IK, constraints and attributes
  to create full control handle for the object.
• example

8
Dynamics

• Dynamics deals with physical properties of
  objects
• Mass, moments.
• Stiffness and damping (restitution).
• Friction (static and dynamic).
• Movement is governed by
• Newtons laws (free movement).
• Coulombs laws (friction).
• Restitution models (many).

9
Dynamics

• Dynamics deals with physical properties of
  objects
• Mass, moments.
• Stiffness and damping (restitution).
• Friction (static and dynamic).
• Movement is governed by
• Newtons laws (free movement).
• Coulombs laws (friction).
• Restitution models (many).

10
Dynamics

• Note free bodies dont simply spin. Newtons
  laws imply a more complicated motion
• Rolling and sliding objects have strange
  behavior movies.
• Impulse Fdt

11
Wrapup

• Chair designs due on Swiki today.
• Who still needs the 2nd round of CD data?
• Make sure you have a copy of assignment 2.