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View Full Version : Arm Rig: Skin Deformation with Elbow and Wrist Twist.

Psylife
03-24-2009, 07:57 PM
Hello all,

I haven't been posting in a long time and It's good to be back! (Not that you really care) :shrug:

So here I Have this character on which I have set up this FK arm and I am currently in the process of skinning it. (I have attached a jpeg).

I have:
One Bone for the clavicle
Two bones for the Arm (The distal one for elbow twist)
One bone for the Forearm.
One bone for the wrist.

Question 1: Is this arrangement a good arrangement? (The character needs to be able to make what a normal human would be able to do which is rotate the Humerus and cross over the Radius over the Ulna Halfway down the Forearm for wrist rotation).

Question 2: The elbow rotation occurring at the most distal bone of the arm (not the forearm) is rotating on the Z axis as it should but also on the X axis (Slightly). Why is this occurring? When I animated it, I simply animated the Z axis. :banghead: Does this has anything to do with the Euler XYZ controller rotation order?

Enlighten me. :)
JessR
03-26-2009, 02:24 PM
it all depends on your weight painting. If you get your skin gradient painted right you can handle it fine. My personal rigging preferences is to do a 5 bone arm, Shoulder>Bicep Twist>Elbow>Forearm Twist>Wrist, with the forearm twist set to take half the rotation of the wrist, and the bicep twist handling the rotation of the arm instead of the shoulder due to preferred skin deformation.
serev
03-31-2009, 03:32 AM
in response to your second question, it can happen based on how the local rotation axes are set and if you're not animating in gimbal mode on the rotate tool. If you're in local or world rotate mode you may get rotations on multiple axes even if you're only rotating in 1 selected axis. In Maya its right at the top of the tool options, but i'm not too sure about other 3D packages...

hope that somewhat helps
Psylife
04-03-2009, 02:04 PM
Thank you guys for the help, I think i am on my way to solve the problem.


Thanks again :wavey:
Keithtron
04-07-2009, 08:33 PM
it all depends on your weight painting. If you get your skin gradient painted right you can handle it fine. My personal rigging preferences is to do a 5 bone arm, Shoulder>Bicep Twist>Elbow>Forearm Twist>Wrist, with the forearm twist set to take half the rotation of the wrist, and the bicep twist handling the rotation of the arm instead of the shoulder due to preferred skin deformation.

Hmmm.... not a bad idea. I never thought about twisting from the bicep instead of the root of the shoulder, and it makes total sense. It seems like it could definitely help to simplify the tricky shoulder area.
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04-07-2009, 08:33 PM
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