CS 284: CAGD
Lecture #15 -- Tu 10/17, 2006.

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Preparation:

"Subdivision Surfaces in Character Animation" DeRose et al.

Subdivision with Sharp Features

To make subdivision practical, we need to be able to model shapes that have a mixture of rounded surface elements and sharp edges and corners.

Key paper:
"Subdivision Surfaces in Character Animation" DeRose et al.

Warm-Up: Discuss and find answers to the 10 questions below:

What subdivision scheme are they using ?
What are the key additions to that scheme that they have made ?
Why do they prefer quadrilaterals ?
What is the basic approach to creating semi-sharp edges ?
What is the underlying model for cloth simulation ?
How is excessive wrinkling of the cloth avoided ?
What are virtual threads ? -- and what is their purpose ?
What is the data structure to make collision detection efficient ?
What made it possible to apply texture maps and procedural shaders ?
What was one of the general implementation requirements for the Pixar production environment ?

Curve and Surface Optimization

Curve Optimization

What are desirable properties -- and how do we achieve them ?
Curvature-based global functionals: MEC, MVC, Si-MEC, Si-MVC
The generic optimization step: A move that makes things better -- how do we find such a step ?
Perhaps there are many different ways to make things better -- how do we combine them ?
Gradient descent.
How to reach the global minimum, and what may slow it down ...
What is an adequate curve representation ? -- e.g., quintic hermite ? -- or a cubic subdivision curve ?
What are the best "primitives"?
Does this work in 3D ?

Continue to think about your Course Project !

==> PROJECT-PLANNING

Reading Assignment: -- Prepare for Quiz (10/19==>10/24)

Homework Assignment: -- Think about Project: Hand-in two ideas (one paragraph each) on 10/19.