skinCluster

Smooth Skin Attributes

Classic Linear: Sets the object to use classic linear skinning. Use this mode if you want basic smooth skin deformation effects, the same as in previous versions of Maya. This mode allows some volume shrinking and collapse deformation effects to occur.

When a mesh is set to linear skinning, it can lose volume in areas where it is influenced by a joint that is twisting on its axis.
Dual Quaternion: Sets the object to use dual quaternion skinning. Use this method if you’re concerned with preserving volume in the mesh as it deforms around joints that twist.

When a mesh is set to use dual quaternion skinning, volume is preserved even as it is influenced by a joint twisting on its axis.
Weight Blended: Sets the object to use a blend of classic linear and dual quaternion skinning, based on a per-vertex weight map that you paint. See Blend smooth skinning methods.

Use Components: Specifies whether changes to the components of smooth skin influence objects can change their deformation effects on smooth skin objects. If Use Components is off (the default), changes to components do not change the deformation effect. If Use Components is on, changes to components can change the deformation effect.

For example, if your smooth skin influence objects are NURBS surfaces and Use Components is on, moving the influence object CVs can change the deformation effect.

Alternatively, if your smooth skin influence objects are polygonal surfaces (meshes), setting Use Components on makes it possible for changes to individual polygons to in turn deform skin. Otherwise, with Use Components off, the entire shape of the influence object influences the skin but changes to individual polygons can not influence the skin.

Use Components is off by default.
Deform User Normals: When on, the normals of the smooth skinned geometry deform with the skin if the skin has user-defined custom normals. If the skin does not have user-defined custom normals, turning on this option will have no affect. Deform User Normals is on by default.

You can turn this option off to make the skin evaluate faster. For example, if you are animating a skeleton or viewing your character’s skin in wireframe mode, then you do not need the skin normals to deform.
Maintain Max Influences: When on, your smooth skinned geometry cannot have, at any time, a number of influences greater than that specified by Max Influences.

For example, if Max Influences is set to 3, and you paint or set weights for a fourth joint, one of the weights of the other three joints is set to 0 to maintain the total number of weighted influences specified by Max Influences.

This limits the redistribution of weights to a specific number of influences, and ensures that the primary joints are the ones that receive the weights.

Note
If you turn on Maintain Max Influences in the Attribute Editor, the skin weights are not modified until you reassign them by clicking Update Weights.
Max Influences: Specifies the number of joints that can influence each skin point on your smooth skin geometry. Default is 5, which produces good smooth skinning results for most characters. You can also limit the range of joint influence by specifying a Dropoff Rate.
Update Weights: Click to update your smooth skin weighting using the value specified in the Max Influences field. For example, if you change the Max Influence from 2 to 4, each skin point will now be influenced by a maximum of 4 joints rather than the previous 2.
Normalize Weights mode: This drop-down list lets you set how you want smooth skin weights normalized. These options can help you avoid letting the normalization process unintentionally set small weight values across many vertices.

Select from the following options:

None: Turns off smooth skin weight normalization.

Warning
Be aware that this option lets you create weights of greater than one or less than one, which can allow for odd or incorrect deformation as you exercise the character.
Interactive: When on, Maya normalizes skin weight values as you add or remove influences, and as you paint skin weights. As you work, Maya adds or removes weights from other influences in order to make the total weights on all influences add up to 1.0. You can view the exact weights used for deformation on the skinCluster node weightList attribute.

For example, if you change a weight from 1.0 to 0.5, Maya distributes the remaining 0.5 amongst neighboring influences. This mode replicates the normalization process in previous versions of Maya.
Post: (Default) When on, Maya calculates normalized skin weight values as you deform the mesh, preventing any odd or incorrect deformation. No normalized weight values are stored on the mesh, which lets you continue painting weights or adjusting interactive bind manipulators without having the normalization process change your previous skin weighting work.

Selecting this mode lets you paint or change weights without affecting the weights for other influences, and still have the skin normalization occur when you deform the mesh.

Note
Since Maya calculates the normalized weight values dynamically at deformation time, you cannot view the normalized values on the skinCluster node weightList attribute. Your mesh will deform with normalized values, but the actual weight values on your skinCluster node may add up to more or less than 1.

If you use interactive skin binding, this mode is automatically selected for you. (See Interactive bind for smooth skinning.) As a result, for interactive binding, weights are not normalized until you deform the mesh.

For more information on skin weight normalization, see Smooth skin weight normalization and Set normalization mode and normalize weights.