Cineversity

Hi,

Is there a pre-requisite on how to use the preferred joint angle?
My use case does not seem to work.

You can see the problem here:
https://www.dropbox.com/s/hmega38ruz5w5w4/c4d196_preferred_joint_angle_not_working.jpg?dl=0

You can see the illustration file here:
https://www.dropbox.com/s/ax49we19q89749s/c4d196_preferred_joint_angle_not_working.c4d?dl=0

Is there a way around this?

Regards,
Ben

Hi Ben,

Cinema 4D uses as Maya a Pole Vector to stabilize the IK setup.
https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/Maya/files/CSCo-Pole-Vector-constraints-htm.html

Here is your file back with a Pole Vector set up, so the Joints behave as the suggested constellation on the right.
https://www.amazon.com/clouddrive/share/8lEU7VJYgYpZCWZldNirB4PhPP7ve6iQA145cdOTKGE

More about IK, Preferred Joint Angle, and Pole, here:
https://help.maxon.net/us/index.html#OCAJOINT-ID_CA_JOINT_OBJECT_IK_GROUP
especially
https://help.maxon.net/us/index.html#TCAIK-ID_TAGPROPERTIES

I understand the IK set up (Including Pole Vector) as the top level, and in the moment more than two “bones” in the IK chain, the Preferred Joint Angle will have some influence.

All the best

Hi Dr. Sassi,

Thanks for the response.
If you placed both the joint chain (base joint and the ik joint) together, you’ll notice that they no longer match.

You can see an illustration here.
https://www.dropbox.com/s/9336dvowyty8l55/c4d196_preferred_joint_angle_not_working_02.jpg?dl=0

Correct me if I’m wrong, that was actually the purpose of the preferred joint angle so you can bend it in the specified angle without using pole vector, which modifies the original base joint chain.

As a background, the reason I’m picky with the placement is because I’m rigging an anatomical figure.
It turns out the initial “bend” angle if you follow the pivot of the bones is facing at the back. But the behavior should be bending at the front.
You know its the pivot because it doesn’t intersect with the other bones.

Currently, I have two joint chain to solve this. One is the anatomical joint and the other a joint chain for IK solving. It works. I was just wondering if I can combine it to one.

Anyhow, no further action needed. Thanks for the help.

bentraje - 08 January 2020 04:01 AM

“…Anyhow, no further action needed. Thanks for the help.”

You’re very welcome, Ben, thanks for the reply!

I wouldn’t leave a problem open here, as long as there is a solution for it or something that makes it work anyway.
Stopping midway would be misinformation and lower the trust in the application. You don’t need to reply, I respect that you move on of course.

Thanks for the image, this is not a problem of the preferred rotation, it shows clearly that you need to adjust the
Attribute Manager> IK> Tag> Pole VectorAxis or Twist parameter.

Either chose the axis appropriately or use [here]180º (which is my best guess, if I had the project file, I could be more precise.
The initial file had all axis pointing equally [relative]).

Here is again the link to the manual going more into detail about:
https://help.maxon.net/us/index.html#TCAIK-ID_TAGPROPERTIES

I hope that saves you some time.

My best wishes for your project.

P.S.: here is an example file
https://www.amazon.com/clouddrive/share/z89UMPsamB8DoqX36WUhn1kqBkty2vIeMWQ9IpbCoet
The Goal is a child of the Non-IK Chain. I adjusted the Joint display width, to showcase this clearly.