Skinning help for 3ds Max?
polycounter lvl 8
Hi!
Does anyone else find character skinning difficult in Max?
I have tried to skin a couple of humanoid characters, based on biped, and the results are not that awesome. Especially the upper-arm / shoulder area seems to have totally wrong weights, no matter how much I tweak them. Looks good in the T-pose, but terrible when walking etc.
Are there any third-party apps for this? I looked at BonePro, but that's out of my current budget.
Does anyone else find character skinning difficult in Max?
I have tried to skin a couple of humanoid characters, based on biped, and the results are not that awesome. Especially the upper-arm / shoulder area seems to have totally wrong weights, no matter how much I tweak them. Looks good in the T-pose, but terrible when walking etc.
Are there any third-party apps for this? I looked at BonePro, but that's out of my current budget.
Replies
Just model the arms in a pose which matches their average position.If the person is holding a gun most of the time make it a 45 pose for example.
Do you mean rigging or skinning? I know you said rigging, but just wanted to make sure...
I rigged the current character in t-pose, but I have tried adjusting the skin in other poses as well. Somehow it's just the shoulder area that's never right.
Also, does the mirror vertice weights actually work? I have managed to mirror envelopes, but not really the vertice weights.
And yes the mirror tool does work
You should take a look at CAT Tools if you have max 2011(or 2010 with subscription)
It won´t solve the shoulder problem, but makes the whole animation process easier.
I bet the skinning would be easier with CAT bones and I have tried to use it, but the trouble is, that I have some *.bip motion capture files for those characters and it doesn't seem very straightforward to make them work with CAT.
Even with the "biped" CAT parent the mapping is just a little off -> legs don't move or get placed in the pelvis or something crazy like that. I also tried to remap the bones by hand, but it still doesn't work, so I guess I'm stuck with regular biped if I'm to use those mocaps.
Often times when you animate, you'll find an odd section that you didn't know happened when you moved the body the first time. So I just pause the animation in that section, go back to the skin and re-weight the verts till it looks fine.
Actually I was just doing that with the mocaps
Next, I will try what SpeCter said and lower his arms, before I skin him. In fact, I should probably remodel the back area with arms down - or at least check it's proportions.
It's not 3DSMax.
Firstly, shoulders are a bitch. They are a complicated system with several muscle groups which push the flesh around.
The mesh density - do you have enough polygons to support the deformation? Do you have too many polygons? Yes, this is an issue, there is a balance.
How many bones do you have in the shoulders? Is it spine, clavicle and one upper arm bone? You'll find that at least one arm roll is required, and things get better quickly when you have armpit helpers and some sort of scapula system.
I'm pretty sure I don't have enough polygons for a proper deformation, but it's a game character so I'm on a budget. I might be able to steal some from less important areas.
Good to know, I'm not the only one who thinks it's complicated! It would of course make sense to show the problem as Mark suggested, but this character is for a client, so I cant directly show him.
However, I will make another one for testing purposes during next week. Then I can show you exactly where the problems are.
http://www.pig-brain.com/tut02/tut02_01.htm
The upper-arm/shoulder/chest area is, hands down, the most difficult to model, rig, weight, and deal with during animation. It's an incredibly complicated mechanical apparatus with multiple joints all working in conjunction, extreme range of motions, muscles that span across joints and fold over each other, all sliding around under the skin, buried under muscle mass where it's impossible to see without X-Ray.
Good loops and vert placement supporting how the mesh needs to deform along all three axis is much more important than just throwing more polygons in there hoping it will deform better. An edge can only collapse between the two verts that define it. Too many edge loops in the wrong spot, and you're going to get polygons folding over each other, creating noticeable creases in your geometry. To few, and you get noticeable edges in your sillouhette...especially when the geometry needs to fan.
I second what Rick says. Without at least one helper bone to eliminate the twist along the axis of the upper arm that you can weight to, you might as well just use envelopes and hope for the best. Fiddling with weights will get you slightly better results, and you can favor the deformation you're most likely to encounter...but you're still going to have some major issues in certain poses
Also, make sure you're using the clavicle/scapula bones. An arm will only raise up so far before they engage and take over. Beyond a certain point the arm is actually twisting and bending forward...not up. You can see this yourself by holding your arms straight down, palms toward your thighs, thumbs forward and see how far you can raise your arms toward your head. Note how far you can raise your arms before yoru shoulders start rising. Also note how far you can raise your arms without rotating your humerus back, pointing your palms forward and thumbs straight up. When you do, pay attention to how little of the twist actually carries into the deltoid/shoulder. The arm near the elbow is fully twisting, but as it moves further and further up into the shoulder assembly, the skin above the deltoid is hardly twisting at all. That's the superficial behavior your trying to mimic with a rig and skin weighting.
I highly reccomend against *rigging* on this type of pose. Things are much easier to deal with in a rig when orienations are zeroed out. However, there's nothing saying that you can't put a rig into a different pose to bind the skin to.
Rick, I'd be very interested in seeing this armpit/scapula setup. My rigs typically use a clavicle (with the pivot moved toward the sternum), upper arm bone, and single twist/helper bone for the deltoid area. I have thought about incorporating a driven scapula bone, but that was mainly to correct against the geometry in the back from pinching into the chest as the clavicles are rotated back. My understanding is that the scapula and clavicle bones remain pretty fixed in relation to each another, but the scapula can hinge out a bit in those situations.
I'm at a loss for what an armpit node would do that weighting to the torso would not? I find that getting the blend right between clavicle, shoulder-twist, and 'toros' can be tricky...but more tricky when you're also dealing with multiple spine nodes as part of the torso. Theoeretically a helper node could be constrained to multiple spine nodes, and that single node would simply the weigthing of geometry as it moves out of the shoulder are into the torso.
Other things that can work is a pectoral helper - a child of the upper spine that inherits that rotation but also has a lookat constraint pointing at the upper arm. As the arm lifts you get the chest lifting, but as the arm rotates forwards when lifted (double arm pistol grip) you get volume preservation.
Rick and Christopher, thanks a bunch for your in-depth answers. It would be awesome if you (Rick) could share a screenshot etc of the setup - I'm not sure if I got it from the verbal explanation.
I was travelling yesterday, but I try to get some screenshots here today - although it seems now that you understand the problem very well - I would love to get some kind of armpit setup working - I have only used the standard biped so far.
picked up an older test character and put a biped on it. I didn't do much to it yet.
Apart from the usual adjustments, the only thing I did was to push the clavicle back quite a bit. The skin itself is what comes by default.
I then loaded a test mocap from the samples and while it's still crap, it's actually better in the shoulder area than the character I was talking about. Now, I'd really like to know how to setup the helper bones...
The upper body on that model is very thin, and the rotational point of the arms are very far out because of that.
Looking at the elbows I can see that you have too much geo on the inside - you need either a collapse panel or you'd need a bunch of extra expression driven bones, or you;d need blendshapes.
The Ancient Pig tutorial shows this:
Get the elbow right and that will make the shoulders easier to figure out.
The animation doesn't seem right - look at the running animation shot and look at the green arm. When the arm is forward you need the clavicle to be forwards. Try it yourself, get your body into that pose and put your left hand on your right shoulder. Move your arm about and feel how much your shoulder is moving.
Learning that biomechanical motion will improve your rigging more than any plugin.
I wanted to see how much better bone placement can do before I start modifying the mesh, but obviously that needs to be done as well.
As for the animation itself - it comes from a mocap file (that test too) and I'm not sure if I can affect that very much - of course I should check the settings when loading it, I'm not completely confident with those yet.