Blender’s automatic weight rigging system works really well ! How does it works?

Coming from other 3d packages, I must say that Blender’s automatic weight system for rigging seems to almost work too well, now I am not complaining, and it is not perfect…but it works so well from the get go !

I couldn’t help wondering “how”.
Does anyone knows what is Blender doing behind the scene to achieve this magic ?
Heat map search ? Volumetric voodoo ? What’s going on ?

I know it’s not envelope since there is an option to use that instead of the automatic weighting system.

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Yes, I also think Blender auto-rigging is impressively effective, and would also like to know more about the technique(s) behind it, although I’m not a coder, but an outline would be interesting.


[…] It calculates how much influence a particular bone would have on vertices based on the distance from those vertices to a particular bone (“bone heat” algorithm).

So its “bone heat” algorithm. I didn’t find and doc explaining it.

I’m not sure if this is that algorithm, but it may be this:

Since Blender is open source we can look our self how excacly it is implemented works:
function ED_object_vgroup_calc_from_armature and add_verts_to_dgroups
function heat_bone_weighting

BTW i found doc that cailms is better than bone heat:
Bone Glow: An Improved Method for the Assignment of Weights for Mesh Deformation
It would be interesting to have this implemented if it gives actually better results.