CIS683 Exam Study Guide
Autumn 2010
Midterm and Final are closed book, closed notes - and no calculators are allowed.
Answering questions
- Whenever you are asked how to compute something, you only need to set up the computation, not actually perform it.
- I am not interested in having you memorize the more complex equations we cover.
However, you should be able to explain any equation if I give it to you.
You should be able to discuss tradeoffs between approaches.
You should be able to combine techniques to solve a given problem.
- The more specific you are in your answer, the more credit you will recieve.
Your answer should convince me that you know the material.
- Always give reasons for your answer.
A simple 'yes' or 'no' to a question will recieve little or no credit (even if it's the correct answer).
- I give extra credit whenever possible - write down what you know about the question
- Review your labs. I may ask questions specifically about the lab assignments.
Go directly to Final
Midterm
The midterm is 48 minutes long, is given in the regular classroom, during regular classtime (during the class indicated on the schedule).
List of topics
- representative, not necessarily exhaustive
- Introduction & Background
- Background & Terms
- 3 approaches to computer animation: data-driven, simulation, in-betweening
- interpolation is in-betweening
- key framing
- main.c
- Technical Background
- transformations, homogeneous coordinates
- display pipeline as transformation between spaces
- translation, rotation, scale (, shear)
- error considerations of transformations
- Interpolation
- Curves
- Continuity
- approximation v. interpolation
- global control versus local control
- Information required from the user
- complexity of curve
- Lagrange
- piecewise cubic
- P = UMB = FB = UA
- Hermite
- Catmull-Rom
- Blended Parabolas
- continuity at junctions of curve segments
- speed control
- Orientation representation
- align object to vector
- fixed angle, euler angle, axis angle, quaternion
- gimbal lock: interpolation of representations
- quaternion math, linear (slerp) and cubic interpolation
- Frenet Frame - undefined case, continuity
- path following, banking
- Interpolation-based Animation
- keyframing
- object interpolation - vertex displacement
- 2D grid
- 2D skeleton
- global transformation
- FFDs
- morphing
- Hierarchical animation
- tree structure
- nodes = data + transform
- arcs = structural transform + articulation transform
- tree traversal, animation
- Multiple appendages
- FK - tree traversal
- IK, analytic, Jacobian, pseudo-inv of Jacobian, transpose of Jacobian, Cyclic coordinate descent
- Physics-Based Animation
- Numerical Integration
- explicit (forward) Euler
- midpoint method
- 4th order Runge-Kutta
- implicit (backward) Euler
- semi-implicit Euler
- forces
- gravity, springs
- static and kenetic friction, viscosity, dampers
- elastic and inelastic collisions
- conservation of momentum
- kinetic energy
- coefficient of restitution
- center of mass - discrete approxiimation
- particle systems
- many particles
- simple physics
- aging fo particles: death and reuse
- interaction with environment, not with other particles
- simple illumination
- spring-damper-mass system
- mass points
- structural springs,
- shear springs,
- bending springs
Table of Subjects - approximate percentage of midterm
Introduction & Background
| 5%
|
Interpolation
| 45%
|
Hierarchical modeling
| 30%
|
Physics Based Animation
| 20%
|
Sample Questions
- What are the 3 general approaches to animation?
- What is the quaternion representation of a 45 degree rotation around the y-axis?
- What is rationale for using the transpose of the Jacobian in Inverse Kinematics?
- Set up the matrices to compute the rotation of the moon around the Earth as the Earth rotates around the sun.
Use two-dimensional motion with the sun defined at the origin, the Earth initially defined at (100,0) and the moon 10 units away from the Earth.
- What is gimbal lock?
- Compute the Frenet Frame for the following curve - just set up the computation, you don't need to perform the actual computations.
- Why is 4th Order Runge-Kutta more accurate than the midpoint method?
- What's the difference between Blended Parabolas and Catmul-Rom splines?
-
How does a kinematic tree data structure accomodate multiple appendages?
Talk about the representation as well as the travesal of the tree.
-
What ways are there to enforce joint limit constraints in IK?
-
Draw the tangents computed by the Catmull-Rom approach for the points drawn on the board.
-
Explain the use of the pseudo-inverse of the Jacobian and what problems there are with its use.
Final
The final exam is in the regular classroom at the time indicated by the University's final exam schedule.
The final is comprehensive with emphasis on the material not covered in the Midterm.
TOPICS since the Midterm
- Sample Pre-Midterm material
- interpolation
- curve interpolation
- quaternions
- path following
- hierarhical animation
- forward kinematics
- inverse kinematics: pseduo inverse of Jacobian with bias, transpose of Jacobian, CCD
- basic physics
- forces: gravity, springs, friction, damping
- particles
- integration
- Physics (since Midterm))
- rigid body dynamcis
- collision detection: plane, convex polyhedron, concave polyhedron
- collision response: kinematic, penalty function
- impulse force of collision
- energy minimization
- dynamics of linked apendages
- Behavioral animation
- knowledge of environment, vision
- flocking behavior
- prey-preditor model
- cellular v. continuous models
- collision avoidance
- Human Figure Animation
- kinematics of walk
- reaching, reaching
- facial animation: expressions, speech
- clothes
- hair
- Motion Capture
- technology: optimal passive, optical active, magnetic, electro-mechanical
- camera callibration
- joint angle reconstruction
- motion capture databases
- Computational Fluid Dynamcis
- density
- advection
- convection
Relative weights
Pre-Midterm topics | 25%
|
---|
Physics | 20%
|
---|
Behavioral animation | 25%
|
---|
Human Figure Animation | 25%
|
---|
Computational Fluid Dynamcis | 5%
|
---|
Sample Questions
- In computing the impulse force of a collision, what 4 components are there in computing the relative velocity of the points involved in the collision?
- Discuss the forces that are used in controlling the motion of a member in a flock?
- Describe explicit Euler integration. What is the underlying assumption being used with regard to integrating acceleration to produce a new velocity at the end of a time step? This assumption is wrong in the case of time-varying forces such as that found in simulating a spring.
- What is the Frenet Frame? Describe considerations of its continuity.
- In the motion capture process, What is involved in 'cleaning the data'?
- Describe the use of the transpose of the Jacobian In inverse kinematics.
- What are the tradeoffs between using quaternions and using Euler angles to represent object orientation.
- In behavior animation, what are the different types of 'vision' that can be computed for a character?
- Given a rod attached at one end to a wall by a hinge joint, what does the force of gravity do to the rod - describe the situation in terms of forces and torques.
- In collision response, what is the 'penalty method'?
- How does the CCD method of IK differ from the method that uses the transpose of the Jacobian - consider the configuration draws on the board.
- Discuss the problem of tracking markers in mocap. What is the main advantage of active optical mocap as opposed to passive optical mocap with respect to tracking markers
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Last updated 12/2/10
Course web page
Rick Parent