Weight painting: values less than 1 don't produce the right effect

(Alun) #1

Hi everyone,

I’m using blender to help with a facial animation project, but have a bit of a problem with weight painting.

So I create an armature, link my mesh to it and weightpaint some vertices red (i.e. weight = 1.0) so that they are associated with a particular bone. In Pose mode I can grab or rotate the bone in question, and the vertices move as they should. Fine. Then I repaint the vertices with weight 0, and they stop moving along with the bone. Also fine. So far so good.

The problem comes when I try to paint with weights less than 1. Vertices that are painted with a value of, say 0.5, behave as if they have a weight of 1 i.e. they move exactly the same way as if they were painted red, except they’re painted green. The same goes for every weight <1, except for 0, which gives correct behaviour.

An example of why this annoying: say I have a bone that controls the raising of an eyebrow. I paint the mesh around the bone with decreasing weights to ensure smooth mesh deformation during the animation, but then when the bone moves ALL the painted verts move by the same amount, regardless of what weight I´ve given them.

Can anyone help me here? I’m a Blender noob but know a bit animation and rigging. Am I missing some obvious setting?

Thanks in advance.

PS I´m running on Blender 2.45 on XP

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(OBI_Ron) #2

Alun,

Welcome to the forums! I’ll take a stab at this. I had a similar problem not long ago, and unfortunately, I cannot remember where the document is that led me to the solution. I am going from memory here.

To get the effect you are looking for, the vertex must belong to 2 different groups / bones. Say for example an elbow. When weight painting an elbow, gradually, the verts will go from being controlled by the upper arm to the lower arm. So, some verts will be controlled by 2 bones, and weight painted accordingly. If the verts belong to 1 bone only, then the weight paint value will act as 1, regardless. Only when a vert is controlled by 2 or more bones will weight painting less than 1 have an effect.

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(Alun) #3

Many thanks OBI_Ron!

Your suggestion has solved the problem. In particular what I did was paint the whole face with a value of 1 for the ‘base’ bone of the head, and now the lower weighted vertices associated with subsidiary bones move correctly.

Thanks again, you’ve really helped me out.

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