Why won't my armature attach to the object with automatic weights?

Bone Heat Weighting: failed to find solution for one or more bones

bird storm.blend (3.4 MB)

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Select bird and bones - scale up * 10. Apply scale.
Parenting with auto weights worked first time.
Then scale back down again *0.1 and reapply scale.

Sorry, but I cannot tell you why this works.

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I don’t know exactly how it works behind the scenes, but I think blender basically projects out from each bone a certain distance, and grabs all nearby vertices, and I’m guessing, that the default distance it uses for that, is too great for such a small object, so it just gets a massive overlap of all the bones wanting to map to all the vertices, and doesn’t know how to handle it.

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Thanks for the reply…
Sounds like the same problem that simulations have - Blender is scaled to 1/100th of the size other 3d apps use.

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Maybe because of this… ??

Hmm :thinking: i delete the armature binding, remeshed the bird with voxel 0.01m, in edit mode selected the inner part with L inverted the slection and deleted the rest… Object mode select also the armature, parented with with automatic width… sems to work…

I suggested @bandages to post here also to maybe get the solution…

Yes, I’d recommend the same steps here as there-- there’s lots of non-manifold geo and the mesh is tiny, even if not vertex dense. And, same as there, I don’t feel like fixing the non-manifold geo to test my recommendation.

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I fixed the non manifold geometry and the automatic weights worked without having to scale up the object.

Thanks everyone.