View Full Version : Hierarchies and their relationship to pivot points

04-04-2016, 12:31 PM
First let me thank Rebel Hill and Brent Alleyne on their tutorials for IK and Rigging. I'm still having a problem with hierarchy and roots. I set up a basic animation you can see at the link provided. It's a simple tin man robot with tentacles. It's merely an exercise to work in IK. The problem I'm having is I can make him walk, but I can't make him turn. I'm still having a problem with hierarchies. I don't know how to parent the goals to move when I turn the robot. They just stay at their key framed coordinates. I can't put everything in an overarching null , because every time I do that it screws up the walk cycle. How do I move a rig with separate IK and FK chains, so the goals and everything move with the rig?
Secondly the root seems to always be the parent in the hierarchy. When I move the object into a null the root becomes the pivot point of the null and all the IK chains are using that root. Can I create separate roots for each IK chain or doesn't it matter? I had the blue IK line go from the ankle to the body. When I moved the body into a null that was at 0,0 the blue line went to the floor. Will this affect the IK chain?
Also any other tutorials on IK and rigs for walking let me know.Thanks.

04-04-2016, 01:58 PM
From the Scene Editor hierarchy in the video, I think you can parent Null-Left Goal and Null-Right Goal to the main Null (just named Null), which has the WalkAboutArms.Body as the first child. Be sure Parent In Place is on (as shown in the video), and then you should be able to rotate the main Null to turn the entire hierarchy.


04-04-2016, 04:31 PM
You're misunderstanding the purpose of IK, which is to have a control outside of a hierarchy which acts an anchored control for it... you cannot have something be free of movement under a given root and not free of the rotation of that root, it must be one way or the other. Also, the reason your IK lines keep moving around is because you're not terminating your IK correctly...

See here, https://www.youtube.com/watch?v=gd1ds0gKnYU and here, https://www.youtube.com/watch?v=7TodIEAZPao and here, https://www.youtube.com/watch?v=T2VYPnVIW0Y