View Full Version : Shoulder Weights and Skin Deformation
02 February 2004, 05:43 AM
I am pretty new the "Paint Weights Brush" and am having a real struggle with it. Does anyone have a character they feel was weighted especially well? Can they post a couple of screen shots of their "painted weights" on the shouder area? Just to give me some idea as to how it should appear when properly applied?
Or perhaps a link to a thread or website where this has already been covered?
Thanks to everyone in this forum. I have learned so much from all of you already.
02 February 2004, 06:59 AM
theres no way u can get perfect deformations woth just paint wts for the shoulder. Its tricky.
Good paint wts, with correct modelling for deformations, influence objects, extra joints, blendshapes, muscles etc etc, will help u get better deformations. cheers
02 February 2004, 07:20 AM
Thanks for your reply. Obviously I have a ton to learn. I realize that there is much more to it than simply painting weights, but I am trying to learn one concept at a time, and progress to the next step after getting a handle the the intial idea.
I was wondering if I could just see a screen shot of the technique being applied correctly to give me a ball park idea as to how it should more or less be looking.
BTW, visited your site, superb stuff! Really good to see some of the principles of animation applied in your work. Very entertaining.
02 February 2004, 04:06 PM
I'm quite new to skinning myself so take this with a grain of salt:
I'm skinning a low poly character atm (se my signature), and I found (well, stole actually) the following joint setup for the shoulder. My character is modelled in a pose with its arms slightly down from the "Da Vinci" pose.
A clavice/scapula joint right between the base of the collar bone and shoulder blade, i.e. quite close to the spine, but not directly on it.
A Shoulder joint a bit higher than the very center of the shoulder "ball", but still inside the flesh, not placed on the skin.
An Upper arm joint right between the shoulder bone and the elbow, at the center of the upper arm's mass.
An Elbow joint, not placed on the actual elbow tip, but at the center of the elbow, a tiny bit further down the arm than the elbow.
(I also have a lower arm joint right between the elbow joint and
the wrist joint, but that's not what you asked for).
The main thing about this shoulder rig is that the scapula/clavice joint does a lot of the deformation, just like on a real human - try lifting your own arm more than 30 dgs up from the outstretched position without lifting both the scapula and the collar bones too - it's impossible, and the same should be true for your 3d character.
The reason I have an "extra" arm joint at the upper arm is that the deformation of the shoulder is quite different when rotating the arm around its length (bone) axis than around the other axes. This is quite well laid out in this article:
Cane Toad Shoulder Rig Tutorial (http://www.cane-toad.com/tuteRig_Shoulder.htm) (check out the other ones too - they're great!)
When I'm pretty sure my joint setup is good enough to accomodate all the deformations, I start painting weights.
I start with the scapular/clavice joint and check Replace 1.0 and paint everything up to where I'm certain that joint won't affect. Then I go to the shoulder Joint and rotate the joint into extreme pose and start painting the transition to the Clavice/scapula joint (usually with Add 0.1 for the shoulder). When I'm happy, I put it in a new extreme position and find out that I shouldn't have been so happy after all ;) and continue painting. When it's time for the next joint I select Go To Bind Pose and continue.
That's the painting technique I use for all joints - start at the root and work your way out to the leafs by rotating the joints into extreme positions while painting.
Like modi said, you can't get perfect deformations in the shoulder just by painting weights, but you can get them pretty good if you place your joints right.
02 February 2004, 05:25 PM
Thank so much for your help. I was incorrectly informed that weight should be painted in the bind pose. Your suggestion of posing the charcter in "extreme" joint positions and then painting the weights helped alot.
I knew the Swedes would come to my rescue eventually!
02 February 2004, 09:56 PM
01 January 2006, 12:00 PM
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