CG Class 9, Mon 2017-09-25
Table of contents
1 SIGGRAPH 2017 videos
SIGGRAPH is the world's leading CG conference. I'll show various videos from it.
2 Text chapter 3 programs
Now, we'll see in more detail how some programs in http://www.cs.unm.edu/~angel/WebGL/7E/03/ work.
- squarem
3 Slides
We'll continue with the textbook powerpoint slides.
4 3D rotation
- Now we're starting a module on 3D rotations.
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My note on 3D rotation.
- All rigid transformations in 3D that don't move the origin have a line of fixed points, i.e., an axis, that they rotate around.
- deriving the vector formula for a rotation given the axis and angle
- computing the matrix from a rotation axis and angle
- testing whether a matrix is a rotation
- if it is, then finding the axis and angle.
5 Euler and angles and Gimbal lock
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http://www.youtube.com/watch?v=rrUCBOlJdt4&feature=related Gimble Lock - Explained.
One problem with Euler angles is that multiple sets of Euler angles can degenerate to the same orientation. Conversely, making a small rotation from certain sets of Euler angles can require a jump in those angles. This is not just a math phenomenon; real gyroscopes experience it.
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What is Gimbal Lock and why does it occur? - an animator's view.
6 Homework 4 online
- Homework 4 is online; due next Mon 2359. Changed to next Thurs.