A good Shoulder setup, weighting tutorial...

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  11 November 2002
Question A good Shoulder setup, weighting tutorial...

Ive been trying to setup a human shoulder in LW and Im about to go nuts. This is by far the hardest thing I have ever tried to do in LW. Does anyone have or know of a good tutorial on this? Have you got a succesful shoulder setup? Let me se it.

Im going insane here...
Thanks
 
  11 November 2002
Hi..
This looks good.. It's not a tutorial but you can download the scene (shoulder socket test) and see how it works..

http://www.lwhub.com/theory.html
 
  11 November 2002
Hey Firelark, I'm working on the same thing right now and I think I can say, I feel your pain. I've been back and forth between Layout and Modeller about a bazillion times and just when I think the changes I've made in one area are working, I see that they adversely affect another.

The variables begin to gang up on you. Between point weighting, bone placement, mesh layout(i.e. edge loops) it's difficult to tell just what needs adjusting.

Right now I've stripped all but the torso and right arm from my model just to speed things up. I'm playing with falloff bones and expressions to try and isolate some of the problems, but things just seem to be getting more complex. Arrrrg.

[VENT OFF]

-ub52
 
  11 November 2002
The biggest problem for me is when the character is reaching up and behind his back the deformations are so bad. And the whole sholder is twisted deyond recognition. Ive tried using the "Smartskin" technique with bonecontrolled morphmaps that is correcting the geometry. That works fine if you use only one morphmap on a sertain are. If you combine two or more and add the original bone deformation to the eqation the result will become unpredictable and the project will take huge proportions.

I want to keep it as simple as possible. Ive been trying extravagance methods for days now and Im prepared to go back to basic and accept a little less quality in the shoulder region.

Meshbuilder thanks for the link. That was a very usefull link. Often even a simple pictures of other peoples ideas can make the whole differens since it gives you new ideas.

ub52 I would love to se your setups. Ive just scraped my latest setup so I dont have anything to show yet. Im planning to go back to one of my early simpler setups that Ive found worked best so far. Ill post a sample when Im done with setting it up.

-karl
 
  11 November 2002
Firelark, no problem, as soon as I get a chance to put something together I'll post it.

Tell me, are you setting up for IK or FK for the arms? IK seems a little unwieldly, but maybe it's just my inexperience animating.

- ub52
 
  11 November 2002
I havent really decided yet whether to use IK or FK. Im leaning towards FK since as you say IK a little difficult to get accurate poses. And Ive found that mixing IK and expressioncontrolled bones can cause strange behavior when moving.

-Karl
 
  11 November 2002
OK, I've posted a couple of short avi's, 8 seconds each. One viewing the model from the front and one from the back. They're DIVX 5.02 encoded. Here are the links.


http://members.cox.net/rlandry52/frontdivx.avi
http://members.cox.net/rlandry52/backdivx.avi

This is all that's on my web site by the way. Just can't seem to find time to get an official one up.

- ub52
 
  11 November 2002
That is some real good shoulder deformation. Looks like you've been doing this more than I have. Im setting up my new shoulder at the moment. Ill hope to have a clip to show you in a few hours. What does that little bone in the armpit do?
 
  11 November 2002
Quote: Originally posted by Firelark
I havent really decided yet whether to use IK or FK. Im leaning towards FK since as you say IK a little difficult to get accurate poses. And Ive found that mixing IK and expressioncontrolled bones can cause strange behavior when moving.

-Karl

The decision whether to use IK or not on the upperbody should be based on what the character must do in each shot. There is no such things as a universal character rig. If the character has to have its hand stay locked to a surface or move its hand along a surface then thats a good place to use IK. If the character doesnt have to do any of that then why use IK? You can get accurate poses with IK if its set up properly. I also follow the same idea when using expressions. I dont like expressions that do any kind of autocentering. The reason is that the animator typically has to fight with those rigs to make them work right. A good rig is one that is very poseable and doesnt break in between poses. It also doesnt break its pose when some part is moved. Ive seen many so called "Pro" character setups that are anything but that. Its caused a lot of misconceptions to be passed along to new users. The problem most people have with rigging is that they lack experience animating other peoples rigs. Typically the best riggers are those who have some experience doing actual character animation. If you dont have that experience I would find someone who does and rig for them. There is a whole philosphy behind rigging. Its not based on what is technically right or wrong but on what the character has to do and the challenge is what you have to do to make it easily do that.
These are things I teach as well as how to go about doing it.
http://www.splinegod.com/profession...cterseries.html
you can see student WIPs at
www.3dtrainingonline.com/studentwork

BTW heres an interesting rig that uses no morphing or displacement maps.
www.splinegod.com/armtest2.mov
 
  11 November 2002
Thanks Firelark. I can't tell you how many hours I've spent tweaking and still, I'm not totally satisfied with the results. I suppose we are all our own worst critics.

I'm not exactly sure which bone you are referring to as there is no bone in the arm pit. It must be the angle at which I created the clip. There is a hold bone in the back shoulder blade area which serves to keep the mesh from colapsing in and loosing volume as the arm is rotated forward. It is parented to the shoulder bone. There is also a fan bone also parented to the shoulder bone and protrudes up and out of the shoulder joint. Both it and the shoulder bone rotations are controlled by expressions and channel followers to the first bicep bone, the one closest to the shoulder joint.

There is a problem with the rig in it's current state. With the arms resting at the sides you use the biceps pitch channel to swing the arm forward and back. This channel also drives the pitch channel of the shoulder bone to get the nice deformations when the arm is elevated. However, with the arm at the side, rotating the biceps pitch channel makes the shoulder sway forward and back and really looks ugly. I'll try to put up another clip to show what I mean. What I need to do is rewrite the expression controlling the shoulder pitch to have the effect falloff as the as the arm is lowered to the side.

- ub52
 
  11 November 2002
Here is the link to the clip show the arm swing on just the pitch channel and the effect it has on the shoulder. Ugh.

http://members.cox.net/rlandry52/armswingprob.avi

-ub52
 
  11 November 2002
Yes you could use a "Lesser than" expression to remove the shoulder movement expression when the bicep is below a certain angle on the heading. Also you could use maprange expression ( the same expression you would use for "Smartskin" - Morphlink ) to create a falloff effect. I havent tried that last expression but I think it should work.

Have you tried to use IK with this setup together with those expressions? I think Splinegod is right in that IK good to have in certain scenes, like when you'll need the hands to stay put at someplace.

I am just about to fix the weights in the shoulder and then I'll post a sample of my rig.

- Karl
 
  11 November 2002
Quote: Also you could use maprange expression ( the same expression you would use for "Smartskin" - Morphlink ) to create a falloff effect.


I'll have to check that out. Thanks.

I have not rigged the arm for IK, but it's next on the agenda as soon as I get the expressions worked out. I'll post the progress.

- ub52
 
  11 November 2002
This is the stage that i am stuck at myself.. I can weigh, and setup every area except the shoulder area.. i think that mine might be how i modeled the shoulder area.. I definetely need to practice more on getting the shoulder to deform right so i can finally get something going..
__________________
:surprised Lightwave3D.. Nuff said:surprised
 
  11 November 2002
Quote: Originally posted by Infinity3d4life
... i think that mine might be how i modeled the shoulder area.. I definetely need to practice more on getting the shoulder to deform right so i can finally get something going..


This is more important than I had originally thought. I've found that the mesh will deform in a very unattractive fashion anywhere you have more than 4 polys meeting at a point. Try to avoid these at all cost. Superior to this though is haveing your edges flow so they don't fight the deformation, but facilitate it.

- ub52
 
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