Computer Creative Art Lecture 7: Kinematic Linkages

What is the primary characteristic of inverse kinematics in robotic motion?

In a hierarchical modeling data structure, what is a leaf node?

How many degrees of freedom does an unrestrained rigid body in space have?

Which of the following statements about joints in hierarchical modeling is true?

What defines the minimum number of coordinates required to fully specify an object's motion?

What is the main focus of Chapter 5 in relation to motion?

Which term describes a sequence of objects where each object's motion can be described relative to the previous one?

What does Forward Kinematics require the animator to specify?

In which scenario does Inverse Kinematics prove to be most beneficial?

What challenge does Forward Kinematics present with a high number of joints?

What does the motion hierarchy often consist of?

Which branch of mechanics deals with the motions of objects without considering the forces involved?

What is a primary task when using Inverse Kinematics in animation?

Computer Creative Art Lecture 7 (DM427)

Lecture covers Kinematic Linkages
Introduction to relative object motion
Describing object motion is often easier related to another object like the sun in moon's motion.
Relative motion sequences are found in astronomy, robotics, and human figure animation.
This chapter focuses on animating objects whose motion is relative to another object, especially when there's a sequence where each object's movement is easily described as relative to the previous one.
This creates a motion hierarchy.
Components in this hierarchy represent physically connected linkages.
Topics in this chapter include forming data structures supporting linkages, animating linkages by specifying/determining position over time.
Kinematics is the branch of mechanics that deals with object motion without considering the forces causing the motion.
Two approaches to positioning hierarchies are forward and inverse kinematics.
Forward kinematics: Animator specifies rotation parameters at joints, the system calculates the end effector position.
Inverse kinematics: Animator specifies desired end effector position, the system calculates joint angles.
Articulated figures are modeled as a series of connected links by joints.
Hierarchical modeling is represented using tree-like structures.
A root node corresponds to the root object.
Other nodes are located relative to the root node.
Nodes with no arcs extending downwards are leaf nodes.
The node higher up in the hierarchy is the parent, and the one lower is the child.
Graphics primarily deals with revolute and prismatic joints.
Revolute joints have one link rotating around the other link's fixed point.
Prismatic joints have one link translating relative to another
Degrees of freedom (DOF) is the minimum number of coordinates needed to completely describe an object's motion.
A rigid body in space has 6 DOF: three translations (x, y, z), three rotations (around x, y, z axes).
Structures with multiple coincident DOFs are called complex joints.

This lecture delves into Kinematic Linkages and their role in the animation of objects in motion. It introduces the concept of relative motion and its applications in astronomy, robotics, and animation. Key focus areas include forming motion hierarchies and understanding forward and inverse kinematics.