Skin Weights: Copy/import/export Probs

[modelmode]

Hi All,

I really need some help with a skin weighting problem I can't seem to figure out. I can't seem to get the copy skin weights or the import/export skin weights to work in Maya 7.0.1. I've followed the tutorals to the letter, and no luck. Here's what Im trying to do; I have two identical models. One with skin weights, one without. The two models share the same 3d coordinate space, and have identical UVs. The results I get from copy and import/export skin weights are generally not even close. I need to make a minor alteration to the skinned skeleton, and I don't want to repaint all those weights. I figured I could just make a duplicate of it, detach the skin and make my adjustment, and use the duplicate to reestablish my weights, but so far its a No Go.

If anyone can tell me how to do this, or tell me a better way to accomplish the same thing, I would really appreciate it.

Thanks

[dunkelzahn]

Hmm, strange. Basically, when you export a weight map, Maya gives you a greyscale bitmap which regulates each joints weighting. That means you end up with a bimap for each joint. When importing the bitmaps are applied to your other model. No problems so far, hmm?

But there may be problems, when:

-Your joint names don

[modelmode]

Thanks dunkelzahn for the input.

Here is a few more details:

-This model is a human body scan.
-The model is one whole mesh with the body and head uv mapped separately.
-verts 17108 14279
-UVs 20178 16929
-142 joints with 109 degrees of freedom that we use.

Why so many joints? We are building this character for our own realtime app and apparently our app requires a single joint for a single degree of freedom, i.e. the shoulder has three degrees of freedom = the shoulder has three superimposed joints. Don't ask me why this has to be this way, it just does. Now you know why I don't want to paint the weights on this again!

As far as your suggestions, here is what I have learned so far.

-If you duplicate your model using geometry type "copy" and group under "world", you get two versions of the same geomety with the same names, except for the top group node.
-Poly count remains consistent.
-As far as I can recall, no UVs have been altered since skinning.
-No ploys have been moved
-There is history on this surface, and both settings for "Delete Non Deformer history" destroys my skin weights.

I believe the last one is the problem. Is there any way on earth to get rid of surface history without destroying skin weights? ( plugin? mel script? ) I could avoid the problem entirely if there was a way to freeze transforms on a skinned joint. ( plugin? mel script? )

Im really beginning to feel that Im outta luck here.

Suggedtions? Comments? Lifelines?

Thanks

[dunkelzahn]

Do some tests exporting your weights, unbinding your skin, deleting the skins history, rebinding and importing the skin weight maps. And with tests I mean, save a copy and then smash and burn/trial and error with just 3 to 4 joints. You

[modelmode]

Once again, thanks for the input.

I've done pretty much all of the trial and error tests you suggested - noluck. I will have to give the three to four joint test a try tho. If you can think of anything else, please post it. If I come up with an answer I'll post it too.

It looks like there are some really useful scripts on Michael Comet's site. If any one of them work I'll owe you both a big thanks.

"Errrm, you have 1710814279 polygons, that is right? shock"
According to Maya there are 17523 faces to the model. Most of those faces are four sided. When Maya tessellates the faces it divides them into two three sided polygons. So I think the number is 34-35,000 polys. (If my logic is correct) I basically just posted the numbers that the heads up display spit out. I never really thought to do the math

Thanks

[joojaa]

is your uvmep nnoverlapping?

But just out f curiosity why ywoud you transfeer at all.

If the objects are identcal, they are the same mesh. So you could just save 2 differet file evrsions. detach in one tweak and recver to olderstate if it fails.

Andd also if indexing is identical you can sut copy over the whole array.

[dunkelzahn]

QUOTE
is your uvmep nnoverlapping?

Crap, yeah Joojaa

[modelmode]

Huh, I never knew about that. Good call Joojaa.

I guess unless your making a group of characters with the exact same body type you might not run into this problem.

As I said before, this model is a human body scan. The model was textured when we bought it, so we did'nt think anything of it. I've been so busy painting weights, that I have'nt paid much attention. As I understand it, The guy stood there and had his picture taken by a high resolution camera that is part of the scanner rig. I don't know how the texture is created from that, or how it gets uv mapped onto the surface. I suppose someone has to sit down and do it. That would be hell!

If I click on the model and open the UV texture editor here is what I see:

http://www.ccad.uiowa.edu/~beck/4Chris/texture\_uv.jpg

Obviously the body texture is not being displayed. However, if I go into the Hypershade and find the head and body shaders and do a "select objects with material" on them, here is what I see:

http://www.ccad.uiowa.edu/~beck/4Chris/texture\_uv2.jpg

Is this a UV sets issue?

Thanks

[dunkelzahn]

Okay, this might be the problem. Your face and body are one mesh and there are two shaders assigned to the polys of the head and to the body, right? Now if you export the skin weights, then there might be problems where the two UV maps (head/body) collide. Nooooow, my suggestion would be, to fix the problem by moving the head UV

[user_deleted]

QUOTE
However, be careful with that, as your weightings are based on your UV

[dunkelzahn]

Good to hear that. Anyway, we haven

[modelmode]

Hi folks,

Sorry I have'nt responded about this subject, I've been super busy.

Here's what I did: I created new UV sets for the head and body, then assigned all the appropriate UVs to each set. I then went into the window/relationship editors/UV linking/UV centric and associated the UV sets with the proper shader. For some reason it makes a difference which UV set you create first and/or which one you have as your current UV set.

This procedure was successful enouph so as to be acceptible (I still had some weight painting to do). The final solution would have been to move the UVs around as was suggested, but that would have created a whole texturing/texture creation headache that I did'nt have the time to deal with.

Thanks to all here who helped me on this.

P.S. grabbing and moving the UVs is not a problem, but splitting, moving, and merging them? Im not sure.

Chris

[dunkelzahn]

Hey modelmode,

good to hear that your model worked out in the end. About the splitting and merging UV