View Full Version : Maya Skeleton Skinning Problem
08 August 2008, 06:20 AM
I just created a new set of hands with arms, rigged and smooth bound to a skeleton. This is my first project using a skeleton, so keep in mind, I have no experience in this area.
Now I'm having a problem where the tips of the fingers deform when I bend other fingers. I have no idea how to fix this, and it's making my hands look like crap. Does anyone know how to fix this?
Any and all help/comments will be greatly appreciated. Thanks a lot.
(Here is a screen cap of the unwanted deformation)
08 August 2008, 06:38 PM
Read up on painting skin weights ;)
You most likely need to adjust the influences on the skinned surface
08 August 2008, 07:05 PM
Thanks for the direction, I'll do that.
08 August 2008, 07:05 PM
The tips of your fingers have influence from other joints in the hand. Select the mesh and then Paint Skin Weights tool. Select the joints in the hand and looking at the finger tip in question find the joints that have influence on the tip that should not. Ie the middle finger has weight on the Index. Select the joint that is should not have influence and paint the influence with zero value and replacement. That way when you paint the tip of the finger and "erase" the bad values those numbers will get transfered to other joints that should have influence. do this till all the "bad" joints are gone and the only joints that have influence are gone.
Why this happened and how to prevent is that when you bound the mesh to the joints you had selected Add influence on closest joint. Do not do this select closest in hierarchy instead. That way they go to the next joint in the chain and not the next finger over that may be closer.
08 August 2008, 09:42 PM
Your post is a great help Coyote, Thanks a lot! This is exactly what I needed.
EDIT: I've found that when I rigid bind my hands instead of smooth binding them, I no longer have this problem. Is there any great disadvantage to rigid binding?
08 August 2008, 11:06 PM
Do not use Rigid Binding for organic characters. It's not to say you can't, just that it is not the correct solution to the problem. You would rigid bind hard objects. Like the armor on a knight and smooth bind the body under the armor. The best settings I have found to start skin weighting is to select only the joints that need to be used to bind to the mesh and when selecting Smooth bind then apply only to selected joints with a max influence at 4 joints. Do not select Maintain Max Influence (if you do it can be turned off but better to not do it). Set it to closest in hierarchy. And colorize the skeleton.
08 August 2008, 05:41 AM
Interesting, I tried everything you suggested, including removing influences using the paint weights tool, but it didn't work. However, I just now increased the drop off rate from 4.0 to 15.0, and the problem is now so unnoticeable, it's nearly invisible.
Is there any flaw to the method I used? In other words, is there any pitfall I should know about this fix, just as there was with using rigid binding?
Thanks for all your help, by the way, I really appreciate it.
08 August 2008, 04:16 PM
That should have worked unless other joints in the body or hand also had influence. Another thing to do is to just paint the tip of the finger 100% to the bone you want. You also want to HOLD joints that you do not want to possibly get the values or loose their values. There are a lot of ways to go about skinning a character and it is a time consuming operation.
I forgot to mention but the best way to do skin weighting is to put small bits of animation and rotation on the joints that you can just delete later on. On frame one have your finger at its rest and at 10 bend the joint and put a key on it. That way if you move it and other verticies on your character move that should not then you know that that joint has influence on things it should not. Also do your weighting with the component editor open as well. That will show you the mathmatical values each joint has and what it influences and you can find ones that have a small value and zero them out.
Your fingertips should be able to get locked to just the tip joint and the next nuckle down. But know that not all weighting issues can be solved by painting weights. Some areas can only be solved correctly by a corrective blendshape. And that is a whole other animal to deal with. My advice is to find as many tutorials on this as you can and learn all you can as well.
08 August 2008, 07:33 PM
I'd just add that you do not really want to do a Replace with a value of zero. This will really lead to problems. Maya doesn't know exactly where you want the influence to go and will do its best to put the influence somewhere intelligent. This doesn't always pans out.
Rather than replace with a value of zero, select the joint that you do want to influence the wacky vertices and paint a positive value to the problem area.
Painting zero just isn't safe. :)
08 August 2008, 05:06 AM
Just a $0.02 add to this discussion, a workflow that I've come to use over the years.
max influence to 1
turn off maintain influences
Bind to Hierarchy
Drop off 4
Colorize joints off (personal preference)
Remove unwanted influences off
So setting max influence to 1 is going to give you a very rigid bind but also the most control over where you want influence to go to. Let me set where I want falloff and smoothness should go. I don't want this figured out for me.
Again control is key so let me dictate how many influences I want. So by turning off maintain influences it gives me the most control. Now if in a game environment and I can only go up to say 4 inf's and I have 5 or more in some areas then I have control where the pruning should go. Don't let Maya figure this out for me. You will always be fighting with the weights if you have this turned on.
Bind to hierarchy or selected is pretty self explanatory. If you want to be anal and know you won't using certain joints then selected is good for this.
Drop off I leave at default since I bind to inf of 1 there is no drop off so it's kind of mute.
Now I hate the colorize option since some of the colors are too light and hard to see. If you have the option turned on and you want to have them go back to default color then all you need to do is select a joint and type "color;" and presto.
With the remove unwanted turned off, again it's all about the artist having control over what you want.
99.99% of the time I use "Add" instead of "Replace". Using Replace at a value 1 is the same as "Add" at a value of 1. If I want to take away then use Add on the other influence.
Well I could go on and on and no one wants to read blah blah blah!
Hope that's some help and makes it more clear.
08 August 2008, 05:06 AM
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