Blendshape results in undesired movement

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  12 December 2003
Blendshape results in undesired movement

When sliding my blendshape sliders, my character moves in the scene. It does not return to bind pose, it just moves in one direction. This is what I do:

1. Evaluate nodes -> Ignore all.
2. Create blendshapes with default settings (deformation order: default, "exclusive" box unticked).
3. Evaluate nodes -> Evaluate all.
4. Since it now returns to bind pose when I slide my blendshapes I will move the blendshapes input in the list (see picture) to the bottom (it was at the top). But instead of moving back to bind pose, it now moves in one direction. It moves further away the more sliders I slide.

What am I doing wrong?

// Fredrik
  12 December 2003
Maybe you accidentaly move all the verts of some of the targets? Did you freeze the transformations of your targets (can course trouble)? Also there is a local and world mode for the blendshapenode, i think. Maybe place the blendshapenode after the tweak? Ok, just wild guessing. Not in front of maya these days.
  12 December 2003
I tried making a fresh duplicate with no geometry differences at all, making a blendshape out of it. Same problem... so there are no verts accidentaly moved.

I did not freeze transformation.
Tried both local and world.
Tried placing the blendshape after the tweak... still same problem.

// Fredrik
  12 December 2003
you absolutely have a difference in the pivot/center, that is the only thing that causes this kind of problem.

Think of blendshapes like translation keys on every vert. If the center moves in relation to those points, those points, while not seemingly, now all have differenent translations than before.

You gots ta dig real hard and find out how/why there's a difference. (This could be a number of things, btw!)
  12 December 2003
The thing is... I made a duplicate (ctrl+d) of my rigid-binded original without editing the duplicate at all. I immediately created a blendshape between the original and the duplicate (they should have exactly the same geometry and pivot point). Now, after placing my blendshape input at the bottom of the inputs list (same as choosing "front of chain" when creating the blendshape I think) the original moves a bit (just like in the attached picture above).

Now if I make two duplicates from my original and creating a blendshape between the duplicates (not using the original at all), it all works fine. So it seems it has something to do with that the original is binded (rigid bind) to a skeleton.

This is just SO weird.

Could it be because I have a polygon object (which I have binded to a skeleton) that drives the shapeHistPoly of a Subd using the "mesh out"/"mesh in"?
...and I'm using the polygon object as base when making blendshapes.

Edit: All of these objects has the same placement and pivot point.
// Fredrik

Last edited by fr3drik : 12 December 2003 at 08:22 PM.
  12 December 2003
I think I get what's happening. "Go to bind pose" before duplicating. I'll bet your verts are being moved due to your skeleton (ever so slightly). You duplicate that it LOOKS the same as your base model, as you're seeing a live distort, but comparing that to the bind pose, I'll bet it's different. Like I said, one way or the other something is causing different translates per vert -you just have to find out what.

P.S.-Maya 4.5 at work, so I can't open this to confirm. .ma would be better (generally better saving practice anyways, more modifiable and backwards-compatible)

Last edited by JasonOsipa : 12 December 2003 at 08:37 PM.
  12 December 2003
Aaah! I completely did not go to bind pose. Doh!
Huge thanks for waking me up!
// Fredrik
  01 January 2006
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