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

[Fougna]

Hello everybody, I’m currently following the Low Poly Characters Course and I have some problems in the Rigging section.

When I try to parent the armature with automatic weight, I get the following message : “Bone Heat Weighting: failed to find solution for one or more bones”.
My armature doesn’t connect with my 3D model, even though I merged all vertices by distance, checked the face orientation, applied rotation and scale to my model and the armature.

Thanks in advance for your help!

[FedPete]

Hi, not sure what’s happening here. But here are some checks

• Remove all previous weight painting
• Bones? Did you use a ready made armature or build one your self?
• Be sure your model scale is 1 (apply scale if you need so)
• Are the object face normals pointing to the outside
• Are you sure you’ve selected one object and one armature

[Fougna]

Hi, thanks for your reply. As for the checks…

• I removed everything I could before reapplying the automatic weights (bones in vertex groups and armature modifier as well).
• I used the basic human meta-rig from the Rigify add-on, as demonstrated in the course.
• I applied rotation and scale to the mesh before adding the armature.
• Checked the normals with face orientation, the mesh is completely blue.
• I only selected my character in object mode, then the armature. I have no other mesh in the scene.

[Fougna]

Okay, I’m making some progress, but I’m not there yet lol… I don’t understand what happened.

First of all, I saw a video on YouTube of someone explaining to scale x100 the armature linked to the mesh, and then remove the scale, but it didn’t work for me.

What did work though is that I only scaled the mesh (with the tool, not the values) and left the armature with its initial scale (x1), then when I got to pose mode, I rotated the bones and it connected with the mesh! It was finally moving, but not properly due to the tiny size of the armature.

So, I rescaled the mesh (again with the scale tool) until its size matches the armature’s, and then I applied rotation and scale on the mesh so it gets the same scale value as the armature.

And now it works better, but I still have some issues with the bones and the mesh, as you can see in the screenshot below…

[FedPete]

If scaling was the issue, then it’s best to remove (detach) the armature.
Then fix the scale of the object, and add the armature again.
Besure to remove the old weight painting data. See vertex group below.

Scaling is a difficult aspect.
Because the object itself is something different then the inner mesh data.
And Blender works a lot with the mesh data.
If object is scaled, the inner mesh data has still the old coordinates (unscaled).
That is why you get strange deformations on the object mesh.

[Fougna]

Again, thanks for your answer @FedPete. Unfortunately, it didn’t work out.
I started all over again and recorded the process on video, there must be something that I’m missing.

https://youtu.be/rmr-NXUNUgQ

[NP5]

Try this.

[SOLVED] Bone Heat Weighting failed (Automatic Weights doesn't work in Blender)

[Fougna]

Okay… ready to self-facepalm me in 3, 2, 1…

Sooooooo, how embarrassing… I thought I selected all my vertices to merge all possible duplicates, turned out I forgot to activate transparency, therefore all the vertices in the back were not selected the first time I tried.

With transparency activated, I removed 8 more vertices, and the rigging now works properly.
Sorry for that little waste of time, and thank you again for your help!

[FedPete]

I’ve made that mistake many times.
On the positive side, you never forget this …