I need smooth skinning help

[Luddy]

Maya "sucks" at weighting and you almost always will have to PAINT skin weights on every joint. It takes some WORK.

For skinning, I use the default but change to selected joints (don't select the end of joints). I use selected joints because of my setup, I have parented joints that hang out (orient switch) and are along for the ride. :bounce:

[mustique]

I'm probably not a master when it comes to skinning but here are my experiences.

To my knowledge its always good to go with "use selected joints" since there will be always joints that don't contribute in skinning like tip joints of a hand. This option makes weight painting easier and increases performance too.

The influence of 5 means that the 5 closest joints will effect a region of geometry which might be inconvenient for most situations. 3 or 4 would be easier to manage and faster too.

Weighting with the component editor causes often less headache then artisan. For example when the whole head of a character needs a weigting value of 1. "Keep weight toggle" is helpfull if you don't want to effect the weights of a joint (it disables weight normalization) you already set up.

The thing is that smooth skin alone isn't enough. In areas like the shoulder I managed to make use of influence objects with blend deformers. But I couldn't make out the influence object settings for areas like fingers. Here my influence objects affected other fingers too. Would really appreciate some tips on that myself. Finally don't forget mirroring of your weights. Saves time.

It would be really great to have some of the linking tools of XSI
in Maya, that makes bulging of critical areas so easy.

Hope I didn't comment on things you already know. :hmm:

[dmcgrath]

Just like mustique and Luddy mentioned.
Always use "Selected Joints" options. The trick is to do it in stages. Select fewer bones and bind the body. Even a one-piece poly character can have a bunch of bind nodes on it. It's not a huge deal. Depending on where the bones are really helps you in determining the fall off rate and the influences. The spine has more bones typically, so it should have more influences than the hand (usually 3 or 4).

"Weighting with the component editor causes often less headache then artisan. "
Yes, the component editor is your friend. Spend a lot of time in there adjusting weights, vertex by vertex, first. And then go to artisan for some finer blending.

I know I'm just repeating things, but they are the most important points to get into when first skinning. You don't need to worry about blendshapes or influence objs. yet. Those come later and are really important for "fine tuning" you mesh, but you need to get the broad strokes down first.

Good Luck.

[kmp3d]

thanks for the advice guys.... I'll give it a try (probably next week since I've been messing with smooth skinning for about a week) yeah my mesh is one piece of geometry so I have been using bind complete skeleton. I've never thought of using bind selected joints and multiple skin nodes..... anyway thanks again..... I may have more questions so keep watching for me

[sedric]

also, if you are working in the componant editor, i find it helpful to turn weight normalization off. then you will have to manually add the values you set to 1 but it is a lot easier than trying to do it with weight normalization on.

hope that helps,

sedric

[MDuffy]

Originally posted by dmcgrath
Just like mustique and Luddy mentioned.
Always use "Selected Joints" options. The trick is to do it in stages. Select fewer bones and bind the body. Even a one-piece poly character can have a bunch of bind nodes on it. It's not a huge deal. Depending on where the bones are really helps you in determining the fall off rate and the influences. The spine has more bones typically, so it should have more influences than the hand (usually 3 or 4).


I don't think I'd suggest using multiple bind nodes on a single mesh. Doesn't that make it difficult to weight in the component editor? Also, what if you have to remove the skin cluster, change the geometry, and re-apply the weights (with the saveWeights.mel script from Big Idea)? Wouldn't having multiple bind nodes make this much more difficult?

Weighting is just a tedious process all around. You just have to learn to do it as quickly as possible. I don't paint weights at all. Our characters are low enough poly that we set weights explicity for each vert. I work entirely within the component editor when weighting, and I usually have "Show all columns" unchecked as I work.

When I bind a skin, I will only bind the selected joints, and then I crank number of influences down as far as I can (2 joints?). That way I have fewer weights to undo when I go in and adjust.


Later,
Michael Duffy
mduffy@ionet.net

[dmcgrath]

-------------------------- quote: MDuffy
I don't think I'd suggest using multiple bind nodes on a single mesh. Doesn't that make it difficult to weight in the component editor? Also, what if you have to remove the skin cluster, change the geometry, and re-apply the weights (with the saveWeights.mel script from Big Idea)? Wouldn't having multiple bind nodes make this much more difficult?
--------------------------
I might have mentioned the wrong word, being node. I really meant that when you look at your one piece geometry in the channel box history area you will see in the inputs area, many clusters on a one piece geometry. I just mistyped my intentions.:)

[seasterling]

Also keep in mind that you are moving the vertices based on the rotation of the joint. When you recognize this it becomes pretty clear that weighting will only take you so far.

Get your joints looking "pretty good" and get the geo to "slide or stretch" where you want it to, then add influence objects, etc to fine tune the deformation. How your mesh is constructed is going to have a lot to do with how far you get with weighting as well.

Personally I really like influence objects and joints for most deformations. You can get as crazy as you want with influence objects and SDKs, down to a single vertex if you want.

[kmp3d]

See heres what I got. I created a pretty complicated bi-ped character that I was going to try to animate, it is one piece of pretty dense geometry. I have used smooth skinning before but not really in depth. After a few attempts to skin this guy with not very good results I decided to try another, simpler, model that I have, and that way learn some tricks to apply to my complex character. This model is very very simple bi-ped character (one piece of geometry). Heres the problem I keep running into that I can't seem to evercome. First I just try smooth skinning with complete skeleton and 2 or 3 influences and about 4 or 5 for the dropoff. Then I bend the arm a little bit just to check the deformations... not bad... the elbow deforms fine, the arm pit area collapses a little. Ok heres the problem I check the weights on the hand and the weight is not smooth from the knuckles of the hand to palm and the palm to the wrist. So I figure just flood a smooth a few times..... ok cool the weights looks smooth from the finger tips to the elbow. But now when I bend the arm the geometry on the hand warps. It seems as though the warped vertices are pulling to where the geometry was originally bound. But the weight on the joints looks fine. This warping only seems to happen after I smooth the weight on those joints. What the heck is going on?????!!!!! Sorry to be so long-winded, I just wanted to explain more about what I'm doing. Anyway thanks for the advice thus far..... anything else you would like to add please feel free. :shrug:

[MDuffy]

Sounds like the verts of your palm got weighted to other bones in the skeleton. Try to normalize weights on your mesh. Also open up the component editor and check what bones exactly are weighted to the palm vertices.

Good Luck,
Michael Duffy
mduffy@ionet.net

[dmcgrath]

Quote kmp3d---------------
So I figure just flood a smooth a few times..... ok cool the weights looks smooth from the finger tips to the elbow. But now when I bend the arm the geometry on the hand warps. It seems as though the warped vertices are pulling to where the geometry was originally bound. But the weight on the joints looks fine. This warping only seems to happen after I smooth the weight on those joints. What the heck is going on?????!!!!!
-------------------------------


:scream: Do not use the FLOOD!:scream:
What you did was average(smooth) ALL the verts on the one piece geometry to the selected bones. All of the weighting went to the hand. Flood is really only good if you want to remove all the influence from a selected bone.

[sedric]

you prolly need to enable weight normalization. --->skin--->edit smooth skin------>enable weight normalization

what may be happening is that you are painting with a brush strength of 1. so everything works ok, but when you "smooth" in artisan it gives many verticies weight values less than one. this make the vert want to stay where it was bound. weight normalization makes maya keep each verticies value at 1 no matter what you paint.

here is the meathod i currently use:

1. start at the toes, and work my way to the hip, then change to the fingers, and work my way to the head, then finish off with the torso.

2 i do so with weight normalization ON. when i finish painting a particular joint, i press "toggle hold weights on selected" so the weights i painted are held.


hope this helps,


sedric

[MasonDoran]

Dont forget that a lot of skinning headaches can be overcome by using wrap deformers and influence objects. If you want the muscles to bulge in the right places you need influence objects because smooth binding alone is never enough.....and you should always bind the skeleton to a low res wrap deformer anyways if you have a high res model to speed up the workflow AND have maya update in realtime. Skinning on a low res model be would really fast....and then real control comes in with influence objects.

i suggest getting a hold of the gnomon tuts....this will explain everything you need to know...

[kmp3d]

thanks for the advice guys..... I know there is about a million ways to skin a mesh..... I'll just experiment with some different ways and see what happens......

thx again :beer:

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