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I am trying to weight paint using blender 2.73a, but no matter what weight I assign to a vertex or what shade the weight painting is it always gets influenced 100% by the armature/bone.
Has anyone else had this problem?
I add this picture of a cylinder and one bone. As can seen the weight paint is not uniform, but the entire cylinder follows the bone.
Or am I totally not understanding weight paint.
I also add a link to the blend file below: blend file of cylinder with bone
This is how weights work.
The weight doesn't define an influence of a particular bone; It describes the Mix factor of influence between multiple bones.
So a vertex with 1% weight on one bone and 0% on all other bones will be 100% influenced by the 1% bone.
A vertex with 1% weight on one bone and 50% weight on another bone will be almost entirely controlled by the 50% bone.
In other words, a vertex is always influenced 100%. Weight only controls which bones do the influencing.
To get a result similar to what I think you are expecting, add a second bone weighted to all the vertices by 100%. Now the first bone's weights will cause non-uniform influences, as you might expect.
The explanation given above (by Gandalf3) is accurate, but a little hard to understand for those new to Blender. It may help to clarify how this problem comes about and how to fix it:
When creating bones, Blender will automatically generate a vertex group with the same name; which links the vector weights to the relevant bones. However, an associated vertex group may not be generated if you import an armature, and sometimes when you duplicate / copy-paste / rename bones (or delete vertex groups).
So, if you've got a 'head' bone that's connected to a 'neck' bone, but only have a vertex group with the name 'head', any weight painting done over the neck area will result in a 100% weight. This happens as Gandalf3 explained... if there are no weights (from other bones) controlling those vertices, Blender calculates all weight values applied to the area as 'the only thing that needs to be considered' = 100% influence.
To fix the issue, you either need to add bones, or determine which bones don't have vertex groups and create them (with the same name as the bones - and assign vertices to them).
