(13)

b Λ0

Jb
V0

where Cb ∈ RB×3 are bone centers and Qb = VT
bVb
are the precision matrices composed by bone orientations
Vb ∈ RB×3×3 and diagonal scale matrices Λ0
b ∈ RB×3×3.
When computing backward skinning weights, bone cen-

ters and orientations are transformed as (cid:0)Vb|Cb
(cid:1) =
(cid:0)V0
(cid:1), where Jb are bone transforms in Eq. 11. Λ0

b|C0
b and C0
To model the skinning weights for fine geometry, we find
it helpful to add delta skinning weights after the coarse com-
ponent is well-optimized. Delta skinning weights are rep-
resented as a coordinated-MLP, W∆ = MLP∆(X, ωb) ∈
RB. The final skinning function is the sum of the coarse
and fine components, normalized by a softmax function,

b are learnable rest bone configurations.

b,

b

(cid:0)Wσ + W∆

(cid:1).

(14)

W = S(X, ωb) = σsoftmax
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