Technical Animation Pieces 3

Feb 1 & Feb 6

Here is a collection of information provided in the class.

IK Basics

  1. Gimbal Lock

Here is a link that explains gimbal lock: http://www.anticz.com/eularqua.htm

“Every system that uses Eular angles will have this problem. The reason for this is that Eular angles evaluate each axis independently in a set order.”

The solution for this is to use Quaternion.

2. Different Kinds of IK Approaches

Classic Approach ( Linear Approximation): Not efficient

– Jacobian Transpose

– Jacobian Pseudoinverse

– Damped Pseudoinverse

– Use Nullspace to achieve objectives ( can be used to solve singularity problem)

– Priority ( e.g. hands moving but want to keep feet on the ground)

Solve 1st priority with damped, 2nd with nullspace.

Priority Chain: keep projecting into nullspace

– Linear Search

Other Ways

– CCD ( much faster)

– FABRIK (forward and backward reaching IK)

Other Interesting papers can be found here: http://graphics.cs.cmu.edu/nsp/course/15464-s17/lectures/Feb6ReferenceList.pdf

 

After the class, I find not classic ways easy to implement and also, from what I have seen, have more natural result than classic ones. More research will be put into this and I will keep updating this post.

 

 

 

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