CGTalk - BlendShapes : How to use them with a skinned character?

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Kel Solaar

01-21-2004, 06:28 PM

Hello Everybody :)

So here is my problem: I'm trying to use blendshape with my skinned character but i'm encountering problems

This is a low poly character I use for test purpose. On the image he is in bindind pose and the rig is hidden

http://kelsolaar.3dvf.net/Ressources/MyArt/Temp/BS1.jpg

I want to make a blend shape for having a proper deformation in the elbow region and bulging the biceps. I have try different approaches but they are not very intuitive and efficient. The first is to tweak a second skinned mesh directly in the pose I want to do (here with the elbow rotated),I return to bind pose once the work is finished and i make my blend shape with the first character. The problem is once a joint has been rotated it's very hard to move his influenced vertices because there are not moving along axes and the sculpt polygon tools is
not working properly. The solution is to use the Move component tool but if you have a lot of vertices it's longggggggggg and harddddd.

Here is the pose I want to tweak (elbow and biceps region)

http://kelsolaar.3dvf.net/Ressources/MyArt/Temp/BS2.jpg

Kel Solaar

01-21-2004, 06:29 PM

I also try to save my weights, rotate the arm, unbind the mesh, tweak it (easily because vertices are moving properly) and rebinded it with my saved weights, the problem is that my mesh isn't in bind pose, so I can't rebind it.

Another solution I have tested is to duplicate the mesh in bind pose, create a blend shape between the duplicated and the skinned one, pushed the slider to one, go to the pose I want to edit and start to tweak the duplicated mesh (wich is in bind pose)
seeing the effect on the skinned one, but once again it's not intuitive and predictable.

Here is a picture illustrating what I mean(The deformation is ugly, it's only to see the effect :)

http://kelsolaar.3dvf.net/Ressources/MyArt/Temp/BS3.jpg

If someone have a walktrough or a method :)

Bye!

nottoshabi

01-21-2004, 08:06 PM

Y dont you try doing influence objects and then do the blend shapes on the influence object. Then sdk or write an expression to tie in the rotation of the joint to the blend shape slider.

:bounce:

Kel Solaar

01-21-2004, 09:32 PM

thanks nottoshabi :)
I would like to try the blend shape because I think that it will allow me to do better deformation than influence objects (like in Pan, but yes this is a good idea.

Pan Link (http://staff.ci.qut.edu.au/~barkerc/Final%20PAN%20website/panindex.htm)

I hope someone will found a solution for this problem

The-Shadow-TS

01-23-2004, 04:46 AM

Here's the trick I learn't from my teacher.

If you want to use blenshapes with skinning you have to have to create the blendshapes before you bind the skin for it to work correctly.

Now to keep things flexible what you do is duplicate you model and make it a Master Blendshape. Apply a blendshape from the Master Blendshape to you model. Then you can skin you model. Now all you have to do if you want to add a blendshape is add one to the Master Blendshape and not worry about the skin. All you blendshapes plugin the master blendshape, which is a blendshape for the main model. This way when you always keep the correct order on the main model, blendshape before skinning.

Model Skinned < Master Blendshape < Blendshape

Hope this helps,
The-Shadow-TS

Kel Solaar

01-25-2004, 08:14 PM

Hello!

I have found this on highend :

BodyShape (http://www.animagicnet.no/maya/bodyShape/index.html)

All I have to say is a very big thx to the guys that have done this script! It's very powerfull and make the process of creating modeling joint driven blendshape very easy!

Tolerate

01-25-2004, 09:01 PM

Why not use an influence object under the skin and then u se set driven keys to drive the deformation of the influence object?

thats the way I'm gonna try when i finally get round to finishing my character

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