You can swap an unbound piece of geometry with your character’s bound geometry and transfer all your smooth skin weights to it with the Substitute Geometry menu item.

Substitute Geometry ( Skin > Edit Smooth Skin > Substitute Geometry) lets the various stakeholders in your production pipeline (such as modelers, technical directors, and animators) work on the same character at the same time without having to redo the character’s skin weights multiple times.

If the unbound geometry has been freeze transformed to a different scale and translation than the bound geometry, complete the following steps to prepare your geometry for substitution.

To prepare freeze transformed geometry for substitution

1. Select the skeleton, then select Skin > Go To Bind Pose.
2. Select the unbound geometry, and set its Translate and Rotate XYZ values to 0 0 0 and its Scale XYZ values to 1 1 1.

   The skin and unbound geometry should now be roughly at the same position in XYZ space. If they are not, move the unbound geometry so that it appears to be on top of the skin in your scene view.

3. Select the unbound geometry, then select Modify > Freeze Transformations.

   You can now move and scale the unbound geometry, and the Substitute Geometry operation will produce desirable results.

To switch your character’s bound geometry with unbound geometry

1. Select your character’s bound geometry or skin.
2. -click the polygonal object that you want to swap with the selected skin.
   Note

   • When the piece of unbound geometry you want to swap is the duplicate of a skin (bound geometry), then Substitute Geometry only produces valid results if the skin’s skeleton is at its bind pose when it is duplicated. (See Bind pose.)
   • The unbound and bound pieces of geometry do not have to overlap during the Substitute Geometry operation, but for the operation to produce desirable results, the unbound and bound pieces of geometry need to have been created at the same XYZ position and size.
3. Select Skin > Edit Smooth Skin > Substitute Geometry (or select Skin > Edit Smooth Skin > Substitute Geometry > if you want to set the options first).
   NoteTo cancel the Substitute Geometry operation, press the key.

   All actions taken thus far are undone and your character is returned to its original state.

   The selected piece of unbound geometry moves and rotates to the position of your character’s bound geometry.

   A duplicate of the bound geometry’s skeleton is created for the unbound piece of geometry and the skin weights from the original piece of bound geometry are transferred to the unbound geometry. Also, the new skin is given the name of the old skin to maintain any of the old skin’s connections.

   By default, the original skin is deleted and the unbound piece of geometry becomes your character’s new skin. If you turned on Retain old geometry in the Substitute Geometry Options, the old piece of bound geometry is given the suffix 1.