Why is Blender ignoring my weight painting?

I understand that for weight painting, an area painted with a cool color like light blue is supposed to be mostly unaffected by a bone, while an area painted with a warm color like red is supposed to be strongly affected by a bone. The problem is that for some areas of the mesh, light blue and red seem to do exactly the same thing. If a section of mesh is dark blue (zero influence) then Blender will totally ignore it, which is good. But if there is even the faintest hint of light blue, Blender seems to treat it like red. But this seems to hold true only for certain parts of the mesh.

In the attached Blender file, you can see that the weight painting assigned to the foot bone has a smooth gradation from green at the toe to dark blue at the ankle. But when I move the foot bone around, there’s no sign that the gradation has any effect: the dark blue vertices at the ankle are ignored and everything else (from light blue to green) just moves as a single, frozen unit, as though it were all red. I used to have this problem with the knee joint too–until I de-parented the armature and removed the Armature modifier, then reassigned everything all over again using automatic weights.

Does anyone know what’s going on? I’ve been fiddling with this for hours and I’m not sure if it’s a bug or just a n00b thing. :frowning:

Thank you very much!


Starscream.blend (1.7 MB)

The weights are relative. If a vertex has a nonzero weight for only one group, then that bone will move it with 100% influence, regardless of the absolute value of the weight. If the vertex has the same weight for two groups, then both bones will move it with 50% influence, regardless of whether the absolute value of the weight is 100%, 50% or 1%.

Best wishes,

So you’re saying that to take away influence from one bone, I need to give it to another bone. Wow, I would never have guessed that one. Thanks a whole ton, Matthew. You’re my hero of the day! :yes: