user: Explain Options in complete detail according to the official Blender documentation.

assistant: [image reference removed]

The Armature modifier.

Object
:   The name of the armature object used by this modifier.

Vertex Group
:   A vertex group of the object, which weights will be used to determine the influence of this
    modifier’s results when mixing it with the results from other *Armature* ones.

    Only meaningful when having at least two of these modifiers on the same object,
    with *Multi Modifier* activated.

    Invert
    :   Inverts the influence set by the vertex group defined in previous setting
        (i.e. reverses the weight values of this group).

Preserve Volume
:   Use quaternions for preserving volume of object during deformation. It can be better in many situations.

    Without it, rotations at joints tend to scale down the neighboring geometry,
    up to nearly zero at 180 degrees from rest position.
    With it, the geometry is no longer scaled down, but there is a “gap”,
    a discontinuity when reaching 180 degrees from rest position.

Example of *Preserve Volume* effects.
Note that the icosphere is deformed using the envelopes weights.

|  |  |  |
| --- | --- | --- |
| ../../../_images/modeling_modifiers_deform_armature_preserve-volume-1.png   Initial state. | ../../../_images/modeling_modifiers_deform_armature_preserve-volume-2.png   100° rotation, *Preserve Volume* disabled. | ../../../_images/modeling_modifiers_deform_armature_preserve-volume-3.png   180° rotation, *Preserve Volume* disabled. |
| ../../../_images/modeling_modifiers_deform_armature_preserve-volume-4.png   100° rotation, *Preserve Volume* enabled. | ../../../_images/modeling_modifiers_deform_armature_preserve-volume-5.png   179.9° rotation, *Preserve Volume* enabled. | ../../../_images/modeling_modifiers_deform_armature_preserve-volume-6.png   180.1° rotation, *Preserve Volume* enabled. |

Multi Modifier
:   Use the same data as a previous modifier (usually also an *Armature* one) as input.
    This allows you to use several armatures to deform the same object, all based on the “non-deformed” data
    (i.e. this avoids having the second *Armature* modifier deform the result of the first one…).

    The results of the *Armature* modifiers are then mixed together, using the weights of
    the *Vertex Group* as “mixing guides”.

Bind to
:   Methods to bind the armature to the mesh.

    Vertex Groups
    :   Meshes and lattices only. When enabled, bones of a given name will deform vertices which belong to
        [vertex groups](../../meshes/properties/vertex_groups/index.xhtml) of the same name.
        E.g. a bone named “forearm”, will only affect the vertices in the “forearm” vertex group.

        The influence of one bone on a given vertex is controlled by the weight of this vertex in the relevant group.
        A much more precise method than *Bone Envelopes*, but also generally longer to set up.

    Bone Envelopes
    :   When enabled, bones will deform vertices or control points near them,
        defined by each bone’s envelope radius and distance.
        This lets [bone envelopes](../../../animation/armatures/bones/properties/deform.xhtml#armature-bones-envelope) control the deformation
        (i.e. bones deform vertices in their neighborhood).

        Example of skinning methods.

        |  |  |
        | --- | --- |
        | ../../../_images/modeling_modifiers_deform_armature_vertex-groups-skinning-1.png   The weights of the “arm” vertex group. | ../../../_images/modeling_modifiers_deform_armature_vertex-groups-skinning-2.png   The weights of the “forearm” vertex group. |
        | ../../../_images/modeling_modifiers_deform_armature_vertex-groups-skinning-3.png   The result when posing the armature. | ../../../_images/modeling_modifiers_deform_armature_vertex-groups-skinning-4.png   The same pose, but using envelopes method rather that vertex groups. |