Char Studio Pelvis Problem


#1

I’ve looked at the help, done a few experiments and can’t seem to get around this. I’m trying to rig some robots (nothing fancy, almost cartoony). The torso and hips are combined into one object. Well, here’s a pic of one.

This one is supposed to be a big, piece of crap robot (it’s not just my poor skills). As you can see, he has two spheres coming out of his torso that represent his hips.

In rigging this to the biped, I’m doing a simple linking of the body part to the appropriate bone. The main torso is connected to the one spine link. The two hips are linked to the torso, the two thighs are linked to the biped thigh, etc.

The problem is that when he moves, the pelvis goes all over the place and his thighs wander way out from the hip. I tried attaching the body (with hips linked to it) to the pelvis, but then the torso leaves the head.

I had a similar problem with the arms. The shoulder balls were connected to the torso and the upper arms were linked to the biped’s upper arms. Originally, the clavicals would end up pushing the arms way out of socket when he moved. I fixed that by shortening the clavicle to a length of 0 and moved the upper arms back out to where they should be, so the clavicle now has no influence over the arms.

Unfortunately, if I try scaling the pelvis down to 0, I can’t move the legs back out to where they should be becuase they seem to always stay attached to the pelvis. I thought that turning off ‘triangle pelvis’ would work, but it doesnt.

The only two ways that I could think of getting this to work right are:

[ol]
[li]scale the pelvis all the way down and move the legs back out away from the pelvis. Is there a way to do that? I can’t seem to get it to work.[/li][li]somehow deactivate, or make the pelvis stationary. Can that be done?[/li][/ol]The only other way I can think of doing this is to create a separate pelvis piece, but I don’t want him to look like that.

Help me Obi Wan, you’re my only hope.


#2

Sounds like you are trying to use a combination of linked objects & mesh deformation… you will need to disable & customize the envelopes to achieve this rig. Are the pelvis keys being generated with footstep creation? You can delete those keys, but a better setup would probably work better, that and freeform keyframing.

If you want to post your setup I’m sure somebody would open it up and have a closer look.

-S


#3

No mesh deformations and no envelopes. There’s not even a Physique modifier. The meshes are all separate objects and not attached to eachother at all. They are only linked directly to the bones.

I made a quicky sample that may be easier to see what’s going on. This is the actual biped I’m using, but I redrew the torso down in low polly blocks so it’s easy to see through.


As you can see, the torso is a separate object from the legs. Torso is linked to the spine and the legs are linked to the legs.

However, when it moves, the leg pivots are not staying where they should. Instead, the pelvis moving around is moving the leg pivot locations.


I was hoping that I could either somehow disable the pelvis entirely, or shrink the pelvis down to nothing so it doesn’t influence anything. But when I do that, it brings the legs toward the center of the body, and I can’t pull them back out.

I thought that if I attached the torso to the pelvis it would work, and it did. However, the head and arms then get thrown out of whack since they rely on the position of the spine.


I really don’t know what to do. Like I said, the pieces are separate from eachother and I’d like to keep it that way. However, at the moment, the only way I can see me fixing this is to add a separate pelvis piece to act as the transition between the torso and the hips.

Any ideers?


#4

Have just been trying to replicate your probs, as i thought that it might have something to do with any scaling that you have been doing during your modeling and wanted to try it out before posting…It would help if you just post up your scene though! Try un-linking all your models from the biped and then using the reset xform utility (under the utilities tab - might have to click ‘more’ to get it), reset all your models individually. This will show up any scale and transform errors you might have with their pivot points, which in turn might be messing up your links. Try not to scale anything again before linking each piece to its corresponding biped part and def don’t scale anything once they are linked! Hope that helps.


#5

hmm, this is the second post i replied to and did not have my post show up…

Anyway, i suggested that you unlink all your modeled parts - reset their xforms (using the rest Xform utility under the utilities tab - might need to click ‘more’ to find it) and apply that to each one of you models individually. This will bake all your scaling and pivot point moving done whilst modelling etc and hopefully fix and transform/scale errors i think are messing up your linking. When you then link your parts to the biped, make sure you only link each bit to its corresponding biped bit. best of luck!

POst your file!!!


#6

This is the file I used in the above tests. It’s rigged exactly the same as my real model, it’s just much more simplified for testing.

http://www.allizdog.com/temp/MW_bipedTest.zip

I really appreciate the help, but I think my problem is more simple than you think it is. The very root of it is that my biped has one spine bone, and one pelvis bone. When the character moves, the spine and the pelvis move separately from one another (which is normal). For example, if he bends back and right, the spine may rotate back and right but the pelvis may rotate forward and left.

If my model had a spine (torso) object, and a pelvis object, it’d be fine because the two objects would move just as their corresponding bones move.

However, my object has only one of the two pieces, the spine (torso) and no pelvis. So what happens is, when the spine goes back and right (as in the example I mentioned above), it brings the torso and upper body with it, which is fine. However, the pelvis moving forward and left brings the legs witih it which then makes it look like the legs are leaving the torso.

Like I said, if I had a pelvis object in my model, things would be fine. I just really need to find a way to bypass the pelvis, so the leg bones are attached to the spine, or totally independent, where I can just place them where they need to be, without the pelvis controlling their orientation.

I hope the file and this explanation help. It’s not a scaling issue. It’s simply the pelvis and spine working against eachother and needing to bypass the pelvis since there is no pelvis object in my model.

Thanks again!


#7

Sorry I can’t read max 6 files yet,…

What if you setup your BIP with a second spine link?
From the looks of your model you could create a single mesh and skin or physique it - get back to animating, but I can understand if that is not acceptable. Maybe it is time to build a bones rig? Good luck!

-S


#8

Nope. Unfortunately I tried that. And I’ve tried linking the torso to the pelvis and shrinking the spine down to nothing, but then the clavicles end up moving the arms way out from the body.

I guess I need to just think about rebuilding these things to have a torso AND a pelvis.


#9

ok, had a look at your file and i agree that I was prob looking a bit deeper than we needed too! Although you will have noticed how all the meshes that you mirrored during your modeling have flipped normals now that you applied the Rest Xform…You would now need to either collapse the stack and flip the normals or appy a normal modifier to the top of the stack to corrrect this.These were the issues i was talking about earlier and you can get link/transform errors later becuase of those mesh errors (thay are only brought to light once you reset their xforms - if you were to export those meshes to say a game engine, they would infact have negative scale…). Anyway…

Why don’t you just link the sphere ‘Hips’ to the biped thigh bones instead of the pelvis(so you have the top of the leg and the sphere hip attached to the same top leg of the biped, so they cannot get out of sync). I have played around with that in your file and it looks good…Its the only thing i changed. Well, as good as two spheres can look. Ignore the pelvis - if the ‘Body’ part of your model is big enough to cover the pelvis then it won’t matter.


#10

Thanks for looking, wildyam. When I link the hips to the thighs it’s true that there is no problem between the hips and legs. However, this then causes the problem of the hips (and legs) themselves separating from the torso as he moves.

What really needs to be done is somehow bypassing the pelvis altogether. A way that I can just tell the pelvis to not move at all, so it doesn’t move the orientation of the legs. I’m beginning to think that this can’t happen.


#11

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