Total Confusion

I am currently mapping out all the bones for a human figure, and they have a 1.00 weight, and all the bones deform the mesh fully, but i recently worked on the lower right arm and hand, and the weight is set to the max, yet when i enter pose mode and rotate the bone, the bone seems to pop out of the mesh the further it gets from resting position, and the meshes arm seems to shrink into itself until it gets incredibly tiny, like a midget arm on a normal body…I have checked again and again and i cannot figure out why it will not work. Any ideas?

[>] The problem is that you have too many vertex groups pulling on the vertices in question.

Vertex groups combine their powers on a vertex by the percentage given by the vertex weight.

So if you have two groups, each at 1.0, on a single vertex, each associated bone asserts itself on the vertex by 50%.
If you tune one of the groups for that vertex down to 0.5, then one group will exert 66.6% pull, the other 33.3%.
The more vertex groups, the merrier. :stuck_out_tongue:

[>] So, the vertices in your “hand” should, for the most part, only have vertex groups for the hand bone. The only place other vertex groups should apply are near the edges (lower arm bone at the wrist, finger bones at the knuckles, etc.)

The overlap near the edges is what gives you the nice, friendly, curvy deformations.

[>] How to fix it:
Select your mesh (subserf off) and enter Weight Paint Mode.
Press F9 (Mesh Buttons) and in the leftmost panel (Link and Materials),
scroll through your vertex groups. If, for example, you find that the lower arm is red through the whole hand, thumb, and fingers, then you need to use your vertex paint tool, with a value of 0.0 (and opacity 1.0) and paint out the most of the hand and all the fingers.

Hope this helps.

Well, that did work, like u said…only problem is, there are a couple weird spike polygons that stick out of the hand as i rotate the bone, like it is getting sucked out of the mesh…i checked twice and made sure all the bones were selected. Maybe it is the fact it is not an open hand, but a fist, for easy animation purposes, and i am not selecting all the polygons inside…but then again, i rechecked the vertices assigned to the bone, with a set weight, so that can’t be it…i’m stumped for now…

it might help to know that i lazily put “make vertex groups out of closest bones” when parenting the armature. Thank you for helping earlier by the way. :smiley:

If it’s the file I looked at then the Middle Finger has a spike because it has one vert assigned to 2 Vertex groups, its own and the 1st vertex group in the list (something like ‘UpperArm’).


You were right! it was because there was a slight bit hidden in the fist to another group…awesome! thanks !