Lecture 15: Rotations

In this lecture, we'll consider how to represent 3D rotations, which turns out to be a hard problem.

The required readings are the best material to learn the most important representations from. Look at some of the other readings to help understand what is happening. You should understand the different representations, as well as understand why they are needed.

Required Readings:

For this lecture, the assignment is to understand why representing rotations is hard, and to get a grasp on the methods used in Computer Animation. This may seem like a lot of reading, but its the same material over and over.

  • The Shoemake Quaternions paper from SIGGRAPH 85.This is in reader #2, and its the first of the 2 Shoemake papers.
  • Grassia's Exponential Maps paper. This is also in Reader #2. Note: this is the Second paper by Grassia in the reader.

In-Class Viewing:
  • Flying Logos, Inc.

Optional Readings: 
  • In Rick Parent's book (reader #1) he discusses rotations on pages 66-74. (the table of contents are wrong). It's better on Euler Angles than Quaternions, and doesn't mention exponential maps.
  • You might look at some of the alternate quaternions references to get better intuitions about what they are about.
  • The Murray et. al. robotics text is also a good source for information on rotations.
  • The Shoemake and Duff "Polar Decompositions..." paper is interesting because it shows why interpolating the matrix is way hard. Probably too hard to bother with.
  • Interpolating quaternions is a hard, but interesting, problem. You might look at some of the recent literature on it.
  • The Lee and Shin paper from SIGGRAPH '99 (which will be required reading later on) also discusses exponential maps and their relationship to quaternions.

Optional "Homework":
  • Try animating an object tumbling to see the problems with interpolating Euler angles.

Lecture 16: Rotations and Kinematics

We'll continue to talk about rotations, and look at an important use of them: building articulated figures.

Required Readings:
  • Grassia's "Mathematical Foundations for Motion Editing" (in reader #2)
  • Maciejewski "Dealing with the Ill-Conditioned..." (in reader #2)

In-Class Viewing:
  • TBD

Optional Readings: 
  • Anything else that talks about kinematics

Optional "Homework":
  • Try animating an articulated figure.

Lecture 17: Inverse Kinematics

Required Readings:
  • Zhao and Badler. "Inverse Kinematics Positioning using Non-Linear Programming..." in reader #2.
  • Maciejewski "Dealing with the Ill-Conditioned..." (in reader #2)

In-Class Viewing:
  • TBD

Optional Readings: 
  • TDB

Optional "Homework":

Lecture 18: Motion Capture Basics

Required Readings:
  • Gleicher. "Animation from Observation". (on-line pdf)
  • Parts of Ron Fisher's Chapter on Motion Capture Basics. (on-line pdf)
    Note: this is a draft of a chapter from an upcoming book. You are not required to read the whole thing. You must read the first 4 pages (up to "Pre-Production Planning"), and the section beginning on page 18 ("Generic Model of Motion Capture"). You should look over all of the subsections of "Motion Capture Technology" to get an idea of what each type of technology is and is used for. You don't have to read all the gory details of how to use each one.

In-Class Viewing:

Optional Readings: 
  • There are some other readings listed on the readings page.

Optional "Homework":

Lecture 19: Topics Day

OK, I blew it and didn't prepare a lecture, so I rattled off a list of potential projects.

You were supposed to have read the motion editing readings.

 

Required Readings:
  • Gleicher. "Motion Editing Techniques." Book Chapter to Appear (on-line pdf).
    For now, you need only read up until page 55. We will look at the spacetime approach later in the semester.
  • Gleicher. "Intuitions of Signal Processing (for Motion Editing)". To appear. (on-line pdf)
    This is primarily provided to give you some background to better understanf the techniques in the above chapter.

In-Class Viewing:
  • TBD

Optional Readings: 
  • TDB

Optional "Homework":

Lecture 20: Motion Editing Basics and Signal Processing

Note: James O'Brien from Georgia Tech will be giving a talk at 4pm on April 6th. This is a required lecture for 838. The reading assignment will be one of his paper on the fracture of objects (on-line pdf).

The lecture will be connected with the last set of readings on Motion Editing.

Lecture 21: Other Physics Topics

Note: Steve Chenney from Berkeley will be giving a talk at 4pm on April 10th (Monday). The reading assignment will be one of his papers, on Monte-Carlo methods for simulation control (on-line, also as pdf).

For this lecture, we will review the 2 faculty candidate talks and their associated papers. Both deal with topics in physical simulated animation.

Lecture 22: Motion Capture Processing

In this lecture, we will discuss the process of going from sensor data to skelletons. Unfortunately, there is no reading for this lecture. 

We'll also look at some demos of some projects.

Lecture 23: Motion Retargetting

This lecture will deal with the problem of moving motion from one character to another. We'll talk about why this is a hard problem, and look at the range of solutions to it. 

Required Readings:
  • Gleicher. "Motion Editing Techniques." Book Chapter to Appear (on-line pdf).
    You should have read the first part already, now read the rest.
  • Gleicher. "Retargetting Motion to New Characters" (in reader #3)

In-Class Viewing:
  • Spacetime Swing
  • Motion Retargetting Video

Optional Readings: 
  • Popovic and Witkin. "Physically-Based Motion Transformations". Proceedings SIGGRAPH '99.
  • Lee and Shin. Hierarchical Motion Editing. Proceedings SIGGRAPH '99.

 Lecture 24: Constraint-Based Motion Editing

Today, we will discuss how the challenges of doing constraint-based motion editing by considering one implementation.

Required Readings:
  • Lee and Shin should have been required. But I forgot to require it!

In-Class Viewing:
  • Hierarchical Motion Editing, Video Proceedings.

Optional Readings: 
  • Lee and Shin. Hierarchical Motion Editing. Proceedings SIGGRAPH '99. (on-line pdf)
  • Other papers on Jehee Lee's web site.

Lecture 25: Spacetime Constraints for Motion Editing

Finally, we should get to a discussion of the spacetime approaches for motion editing. The readings were given a ways back, but now we can talk about them more.

Required Readings:
  • Gleicher. "Motion Editing Techniques." Book Chapter to Appear (on-line pdf).
    You should have read the first part already, now read the rest.
  • Gleicher. "Retargetting Motion to New Characters" (in reader #3)

In-Class Viewing:
  • Various videos of mine and Zoran's.

Optional Readings: 
  • Popovic and Witkin. "Physically-Based Motion Transformations". Proceedings SIGGRAPH '99.
  • Gleicher. Motion Editing with Spacetime Constraints. Proceedings 1997 Symposium on Interactive 3D graphics.

Lecture 26: Accessible Animation and Customizable Graphics via Simplicial Configuration Modeling

This is a paper that will appear this summer at SIGGRAPH. The authors have given me permission to discuss it in class.

Required Readings:

In-Class Viewing:
  • Accessable Animation and Customizable Graphics via Simplicial Configuration Modeling

Optional Readings: 
  • Ngo, et. al. Accessible Animation...

Lecture 27: Subdivision Surfaces

Required Readings:

In-Class Viewing:
  • Geri's Game

Optional Readings: 
  • There are a number of papers in ~cs838-1/xtra/Papers/Subdivision including course notes.
  • DeRose at Al. Subdivision Surfaces for Character Animation. SIGGRAPH '98. (it's in the papers directory).
  • There is a nice tutorial on subdivision surfaces in Game Developer magazine. Part1, Part2

Required Readings:

In-Class Viewing:

Optional Readings: