Scale a finished complex character with influences and double skinning


#1

Hi there,
I´ve never encountered a situation when there was no way of scaling a rigged character, no matter how many things are going on rigging or skinning wise. But now I´m working on a character that has double skinning, meaning I´m using influences that have been skinned themselves and this seems to cause major scaling troubles. I´ve attached two Maya sceenshots where you can see the problem.

Scaling the whole character works fine except for the points that are influenced by the poly plane influence object to the characters lower front. The skinCluster on the coat is of course using components to be able to get the effect of the poly plane (the plane is bound to the legs). There are also influence objects on the poly plane to be able to tweak the deformation when there´s bigger leg movement, but I don´t think the cause any trouble. They are parented to the leg joints like any other ordinary influences.

I´m not 100% sure what the problem is exactly. But I made a test scene and I think Maya applies the wrong transformation to the points influenced by the influence object (see the other two pics from the test scene), meaning, it moves the components based on the unscaled state of the group node or something.

Maybe there´s a way of couteracting the wrong transformation of those points? I tried making a cluster of the misbehaving points and counter-scaling them but the result is simply not the same. I think what is happening might be more complex than to correct with a simple counter-scale at some point in the hierarchy. :hmm:

I´ve attached the test scene if you want to give it a try. I´d appreciate any help, there must be a way …
test scene, maya 5.01

cheers,
matthias


#2

Somebody must have stepped over this issue before. Anyone doing skinned influences for a muscle system on a rig that must be scalable definately would have, I think.
So please let me know what you think.

-m


#3

This is a real brain tickler. I ran into a similar problem with a cartoony rig a while ago.

Like you have discovered, your mesh will deform as though the influence object has not been scaled at all. The problem seems to be that the influence object MUST be parented into the hierarchy in order for it’s affect to be seen properly.

When you smooth skin a mesh and then transform with joints, the shape of the mesh moves but the transform node does not. So the transform needs to somehow follow along without affecting the shapes (which would cause double transforms).

Hmm… sorry I can’t help.


#4

Thanx for posting anyways Kiaran!
I´m glad I´m not the only one stuck on this.

-matthias


#5

This is a tricky one that I’ve never ran into before, and yes I’ve made rigs with musscle deformation. The best way is to model everything to scale in the first place. however not much help to you at the moment.

I downloaded your little test scene and after playing with it a little I had one idea, but not the time to test it. What might work is to remove the influence objects from the skin cluster, scale it and put them back again. This would be fairly easy with a script, or perhaps the save weights script on highend3d might work (I’m not sure if it handles CV’s or just vtx). If not then there might be others for nurbs.

This might not be the best solution, especially if you don’t know MEL, but it is a solution.

Richard


#6

That´s what I told the guy I´m doing the setup for ,)

What might work is to remove the influence objects from the skin cluster, scale it and put them back again. This would be fairly easy with a script, or perhaps the save weights script on highend3d might work (I’m not sure if it handles CV’s or just vtx). If not then there might be others for nurbs.

Reassigning would definately work, I´ve done it numerous times actually (saveWeights is my biggest friend. And btw, it does handle vertices as well as cvs and whatnot and it does handle influences correctly )
But the thing is just getting everything to work at one scale isn´t what Im looking after, but I want to have a working rig at every scale. The guy I´m doing the setup for likes to scale the character just a litte bit in a shot just to make him/her appear a bit bigger or smaller.

-m


#7

Hi Matthias,

I have attached your scene with an modified copy of your objects (without IK etc.)

the originally objects are placed in layer 1 (group4), and the new in Layer 2 (group5 & skel)…

what I have done is not assigning the influence object into an skincluster but parented it to one of the joints…

so if you now select the group called “skel” it will scale nicely without strange deformations…

I think the problem with the originally objects is, that there’s somekind of double transformation going on, (properly because of the extra skincluster maybe)…
also if you see on the weightpaint of the originally influcene object on the orig. cylinder, you can see that it’s only the area that is weighted that gives this strange problem…

so I would suggest you not to assign your influence objects as skinclusters (atleast not if you want to scale them)…

hope that helps a bit… :slight_smile:

regards

Alex


#8

Yes, I suspect this is what has to be done.


#9

can you just be lazy and tell him to scale the shot instead?


#10

That´s what I told him of course. I said he couldn´t go beyong 0.8 or 1.2 scaling on the rig without skinning problems.

-m


#11

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