skinning(riging) Armpit

[dogz]

if you know how to use max.s bone muscle deformer ,i woould use that..if you dont, its in max,s help file and it has the best tutorial on how to implement it..hope it helps you out a little

[Transform Gizmo]

theres a few techniques i know of that may help.
one is to use the gizmo's within the skin modifier such as the morph angle deformer. they work good when skinning and weighting by themselves cant provide proper deformation. another thing that can help is to make sure you have the vertices properly weighted in that region. you can weight them individually or in groups by turning on the 'vertice' filter in the skin modifier.
as far as a way of modelling a character to help the skinning stage, sometimes it may work best to model the arms at a 45 degree angle instead of being straight out. it can help reduce the amount of editing you have to do on the skinning stage as far as setting up the mesh to deform correctly.

[Mahlon]

Only problem with the morph angle deformer is that it's going to operate on more than 1 axis, so it pretty much makes it not very good for the shoulder area. You could try FFD deformers or clusters (using linked Transform modifier) to pull some of the verts around. Then use a reactor controller to drive them so when the arm goes up, you get your deformation you want.

Mahlon

[Transform Gizmo]

Only problem with the morph angle deformer is that it's going to operate on more than 1 axis, so it pretty much makes it not very good for the shoulder area.

true, morph angle deformer isnt always the best option when you need a wide range of motion, but it can be a good thing to pick up when your learning how to skin. :)

[Mahlon]

Yeah, it is a good thing to know. Actually, one of the things I'm using now is a plug-in from Di-o-matic called Cluster-o-matic. It's great to set up detailed clusters and translate those from a reactor controller. Clusters=good. :beer:


Mahlon

[Transform Gizmo]

sweet, ive heard good things about that one. have you tried out any of their other plugs?

[mmwizard]

Thanks for the answers. I'll try it out and maybe come back on the subject. Just another question...

When i use a biped, how important is it to adjust the bone thickness??? and what volume does it need. Does it have to overlap the region???

[PokeChop]

Hi mmwizard. I just had this same "PVC pipe under the arm" problem. I know exactly what you mean. Very frustrating. I found a fairly good solution. It is to turn on animate and go to frame 1 and pose your figure arms down (set a keyframe here at frame 1) after you set up your rigging and skinning with the basic skinning settings and you will get the usual "PVC" under the arm problem. Now go to your skinning modifier, select your bone and tweak the weights at the vertex level in the armpit area and you will see the PVC effect slowly dissappear with the arms posed down. Very effective. Nice thing too is you can go back to frame 0 where your model is posed in the default arm out pose to select any hard to reach vertexes under the arm, toggling back and forth quickly with the greater than lesser than keys. I used to try to adjust the envelopes and vertex weights while the arms were stretched out at 90 degrees then do a temporary pose down to see if I got it everytime, back and forth, very time consuming, posing down then back up then back down. I just set a key to a pose down the arms at frame 1 then tweaked my vertex weights and bam, it seems to work much better when you can see the effects of the tweaks in a posed position on the model. Then after you are done adjusting vertex weights, just select the entire model and delete the keyframes at frame number 1 and your model will snap back to your default stretched out arm position ready for textures with correct skinning. No more PVC armpits either! Works great for the legs too. Hope this isn't confusing and helps in some way.

[PokeChop]

Hi again mmwizard. I might be wrong about this but the bone thinkness inside a mesh does seem to effect the regions. I think this is why Discreet added bone fins. I remember seeing some tuts than mention "make sure the bone fits inside the mesh for proper deformation". From this I can only guess the volume does effect the mesh in some way. Kinda makes you wonder since the latest Biped character is kinda scrawny and thin.

Okay here is what I do. I take the default Biped character and convert the Biped parts (arms, legs, spine) down to an editable mesh and then move around the verts to fit inside the mesh area I am working on. I didn't realize you could do this because I thought it would ruin the Biped like destroy the linking or something but it doesn't. So, far example, I will select the arm bone and convert to an editable mesh then go to vertex level mode then push n pull the verts to the arm mesh to fit exactly. Then when I skin, it seems to calculate the envelopes for me better because the bone falls right where I want it to. Hope this helps too.

Bless Character Studio BTW! Now if Discreet would just add it to the next version of Max like they did Reactor...blah blah blah.

[mmwizard]

Wow Pokechop, These are some great tips, I'll start next monday looking at it and try to follow your instructions.
Thanks again

[Mahlon]

Originally posted by PokeChop

Okay here is what I do. I take the default Biped character and convert the Biped parts (arms, legs, spine) down to an editable mesh

Well you learn something new everyday. Cool tip. I've been adding an edit mesh modifier to get the same results. Never thought to try converting to an editable mesh.... Thanks:beer:

Well, actually what I usually do, since I really don't like the look of the biped, is add edit mesh midifiers to all the bones, then take regular max bones, align to the CS bones' pivot/orientations then and attach them to the CS bones with the Edit Mesh modifiers and hide the CS bone elements. It leaves me with a regular max bones skeleton I'm used to looking at.

Mahlon

[ninjacore]

yo.

i might be too late for this, but here goes...

i'm having same probs. i'm wanting to skin and rig this charcter but its the arms where i keep getting stuck.

the character i did before this was my first time skinning and rigging, and it was a disaster. i reboned, skinned and re rigged god knows how many times trying to sort this problem.

it seems to be in the armpit, the vertices either dont move, or get sucked right in. also, the shoulder flats straight out, goving the charcter weak looking shoulder muscles.

i just want to know whats the best way to model the armpit/shoulder area. also, does the position of the bone which creates the shoulder joint have anything to do with how the skin behaves! i mean like, a little into the arm mesh, or more in towards the main baody of the mesh.

heres a pic..:airguitar

[ninjacore]

you see, what if i go and adjust the weights off each vertice in that region, its still really hard to get a fine balance. because if i turn those vertices right down, it looks ok, but if i raise the arm up, it stays rigid and theres just a whole lot of poly strecthing. BAD!.

i also tried adusting the envelope as a whole, but that results in some awful poly strecting around the shoulder.

aaooowww, i cant win!:banghead:

[Stroker]

While I haven't studied armpits much, adjusting the position of the bones/pivots usually does have a dramatic affect. At least, that's been my experience with hips/legs. I used to have a terrible time with hips/legs. Then I looked at some anatomy pics, adjusted my bones accordingly, and they haven't been giving as much trouble as they used to (turns out my pivots in the hip/legs was too high and too close to center).

Another habit I have is to do a mock rig as I'm modeling. Just a few bones and Skin. Once I see how it goes, just delete the mock rig and get back to modeling. This helps me get a feel for how the bones will be positioned for the final rig. Also helps me adjust geometry before the model is "final" (and is a good break from modeling).

Looking at your example, I would say that the bone/pivot are too far out.

[Stemy]

hi ninja core,

you can try assigning each individual vertice to the particular bone. whether it is the upper arm or the shoulder.

both the physique modifier and the skin modifier has this option.

[Airflow]

try using more than one bone for the sholder, like a twist wrist setup.... you need the control weight to fall off as it gets further down the arm, away from the sholder bone... this helps a load....

[Kaostick]

Im surprised no one has mentioned this, but have any of you tried the skin morph modifier? i used it on the last characters i had to skin, and it was amazing. Incase you dont know, it allows you to set up morphs based on bone angle.

[DDS]

yeah but this thread if from 2003, and skin morph is from 2004 I think.

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.