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View Full Version : Help!...scaled rig--smooth skin deforms


compubimbo
03-08-2008, 03:35 AM
Howdy,

This is my firt post to this forum, but I have referenced it MANY time for advice over the last couple of years. I have searched for the answer to my particular problem, but can't seem to find one, so I'll post it in hopes that someone might be curious enough to take a look. BUT... be forewarned, I do not consider myself a rigger and it may be pretty messy in the parts I made from scratch...

My problem with this rig is most likely a skin bind issue. I noticed it slightly when I first joined the head and the body (they were built as separate rigs.) It was not enough to cause me grief, though, so I just went on and ignored it. Now, two months later, it's time to drop Fred into his truck in my scene. Wouldn't ya know it, I have to scale him and find all kinds of issues! I finally fixed most of them-- so that he scales properly by the main control. Unfortunatly, this earlier skinning issue has popped up again.

What happens is that the skin around the base of the head (and top of the neck respectively) deforms in strange ways when scaled. My target scale for Fred will be .0145 but right now he's at 1.

If anyone has some spare time (*cough*) and wants to take a stab at it, that would be awesome. I have spent about 6 hours on it and still am getting nowhere. I am zipping up the .mb file along with a note with more specific info on the rigs I used. It can be downloaded from here:

http://kams.stuff.googlepages.com/pls_help_Fred.zip

Thanks!
Kam

Geuse
03-08-2008, 03:13 PM
Ok, it's done. However there wasn't anything wrong with it to start with. I just think you scaled the whole top group. this would cause some nodes to have a double transformation which led to the awkward scaling. like for the skin is not supposed to be scaled since it already driven by the bones. So actually your rig works fine, you just have to scale it from the big 4 way arrow in the bottom of the rig by scaling the curve ctrl called "blok_supermover". However I organized your rig slightly by moving the master ctrl "blok_supermover" out of the group called "Entire_Body" and then put the "Entire_Body" inside "blok_supermover" what had to be done next is to select the group "Entire_Body", hit ctrl+a and go into the attribute editor and then check off "Inherits Transform" under the tab "Transform Attributes" and you're good to go.

If anything else or if something is unclear, just, you know! =)

Good luck!

compubimbo
03-08-2008, 05:45 PM
Hi Geuse,

Thanks for checking it out. I think I followed your instructions correctly, but I am still having the same problem. Normally when I scale him by the big 4-way arrow, everything scales fine except the skin at the base of his neck on his head, and the skin at the top of the neck stub of the body. I agree that it seems to be double transforming, but I'm not sure why. I am pretty sure it has to be double deforming at the bind level, though, as I can see the deformation happening slightly when I was trying to break the rig in construction (getting it ready to animate). I don't see the horrible deformation until I've scaled him down past 50%--by 25% it's very obvious. If you have any other ideas, I'd love to try them out!

Or if anyone else wants to take a stab at it!

Thanks again for your time!
Kam

Geuse
03-09-2008, 12:04 AM
Hi again. Now I've been trying to figure out what the hell is up and down and been ripping my hair in the process, but I don't get any wiser I'm afraid. Can't figure out what is wrong.
If you don't find a solution, I'd suggest that you disconnect it and create a new joint chain and add some blendshapes to the head, maybe just a few if he's not supposed to talk.

compubimbo
03-10-2008, 09:03 PM
Hi Geuse,

Oh No!!! I didn't mean to stress you out with it!!! Thank you so much for taking a look, though. I have to say it's the strangest rigging issue I've come across... I haven't had a chance to look at it again (I've been trying to animate other parts of my scene) but logically the only thing I can think that may be causing the problem is the different scales in the skeletons. But it still doesn't make sense to me that this would cause the problem since the skins are joined independently of eachother-- maybe the transform that hooks them up has translated something strangely??

Anyway, I will look into disconnecting and trying to reconnect again and see what I can come up with. Hopefully all will work well. I am trying to avoid blendshapes since most of the shots of him will be facial closeups-- this is why I chose this rigging system, to allow for more subtle shifts in the animation.

I will post my results in a couple of days-- after I have a chance to break it apart and reconnect.

Thanks again for your help and advice! And as always, if there are any other suggestions out there from anyone, they are totally welcome!

Kam

Geuse
03-10-2008, 09:19 PM
No worries, I needed a haircut anyways.
Also, I wanted to know what was wrong to learn myself.
I agree. This is by far the strangest rigging issue I've seen even though I've not many to compare with.
Anyway, It seems this is a result caused by his manipulators on his face in some way. Never did any deep digging to see how it was setup.
Deleted a bunch of nodes and his whole body etc, but the problem didn't seize to exist so I eventually had to throw in the towel.
I truly hope you can get past this in some way without any major time loss.
Would be great if someone else took a crack at this so I too could learn why this happens, because it keeps bugging me too =).

compubimbo
03-11-2008, 02:04 PM
ok, I've got an update on the rig. First off, I have to say that this is the first time being a pack-rat has actually been helpful. I have about a gig worth of old .mb files just from building Fred. I finally got around to deleting them all about a month ago (since he was finished) but never emptied my Recycle Bin. yay!

So I pulled out all my files and stepped back through them one at a time. Finally I got to the point where he was working properly. Long story short, I changed the geometry after the bind-- which I didn't think I did. When I put the two together, the neck stubs for each didn't match up, so I tweaked them. But I really thought I took him apart before doing it.

Anyway, I haven't gotten around to trying to tweak the neck area again. I'm not sure if it was just the geometry change, or the fact that it was changed after joining the two (at different scales). I will post again once I dig a little farther.

Kam

compubimbo
03-13-2008, 01:55 AM
Turns out that any geometry tweaks I make at the scaled down level are fine when he's small, and any at the big scale are fine in the big scale. The geometry tweaks just don't scale properly.

Anyhow, that's about it. I've rebuilt the neck area and all seems fine now. Onto the animation! Thanks for the help, Geuse!

Kam

Geuse
03-13-2008, 07:24 AM
I actually tried to delete non deformer history, but I guess tweaking doesn't apply to this.
I'm glad you got it working.
Good luck with animation and you're welcome!

twedzel
03-15-2008, 12:56 AM
Just to give you some closure on this. I tore apart your rig completely and found it all to be in working order. The problem was happening in the same place on your body and head. I would doubt two skin nodes would be currupt since they rarely are in my experience. So it wasn't in the skin cluster or in the tweek node (turning it's envelope off did not resolve anything). But I did manage to get it into a state where it was giving me error messages when selecting the offending verts. Which leads me to suspect some bad geo. Something got in there that wasn't supposed to be there.

Duplicating the mesh and rebinding it to the exact same deformers and transfering the weights fixed the problems. Leaving me to believe it was in the original geo. Which got wiped away when duplicating the mesh.

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