Skin > Bind Skin > Smooth Bind

This menu item lets you bind geometry to any transform node or hierarchy of nodes such as an empty group node or a locator. For example, you can create a deformation effect by binding a polygonal mesh to locator nodes that are connected to the CVs of a spline curve.

Using the Smooth Bind Options, you can limit the number of joints that influence nearby skin points and limit the range of influence for joints.

Skin > Bind Skin > Smooth Bind >

Opens the Smooth Bind Options, letting you set the following options.

Bind To

Specifies whether to bind to an entire skeleton or only to selected joints.

Joint Hierarchy: Specifies that the selected deformable objects will be bound to the entire skeleton, from the root joint on down through the skeleton’s hierarchy, even if you have selected some joint other than the root joint. Binding the entire joint hierarchy is the usual way to bind a character’s skin.

This is the default.
Selected Joints: Specifies that the selected deformable objects will be bound to only the selected joints, not the entire skeleton.
Object Hierarchy: Specifies that the selected deformable geometry is bound to the entire hierarchy of the selected joint or non-joint transform node, from the top node down through the entire node hierarchy. If there are any joints in the node hierarchy, they are also included in the bind. With this option, you can bind entire pieces of geometry to nodes like groups or locators.

NoteWhen using the Object Hierarchy option, you can only select joints or objects that cannot be skinned (for example, group nodes or locators—not pieces of geometry) as the initial influences in the bind.

Bind Method

Specifies whether joints influence nearby skin points based on the skeleton hierarchy, or based only on joint proximity. Select from the following options:

Closest In Hierarchy: Specifies that joint influence is based on the skeleton’s hierarchy. This is the default.

In character setup, you usually want to use this binding method because it can prevent inappropriate joint influences. For example, this method can prevent a right thigh joint from influencing nearby skin points on the left thigh.
Closest Distance: Specifies that joint influence is based only on proximity to the skin points. When binding skin, Maya ignores the hierarchy of the skeleton. In character setup, you will usually want to avoid this binding method because it can cause inappropriate joint influences. For example, this method can cause a right thigh joint to influence nearby skin points on the left thigh.

Skinning Method

Specify which skinning method you want to use for the selected deformable object. See also Smooth skinning methods for more information.

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.

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: Select to turn off smooth skin weight normalization.

WarningBe aware that this option lets you create weights of greater than one or less than one, which can allow vertices to move too much or too little as you exercise the character.
Interactive: Select this mode if you want the weight value you enter to be used exactly. When you use this mode, Maya adds or removes weights from other influences in order to make the total weights on all influences add up to 1.0.

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: This is the default. When Post mode is active, Maya defers normalization calculations until you deform the mesh. This 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.

NoteWeight values do not always add up to 1 when you use Post normalization mode, but the mesh still deforms with normalized weight values.

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.

Allow Multiple Bind Poses: Lets you set whether you want to allow multiple bind poses per skeleton. This option can be useful if you are binding multiple pieces of geometry to the same skeleton.

When on, you can bind the separate pieces using different bind poses for each. When off, you must bind all pieces of geometry with the skeleton in the same bind pose.
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. See Dropoff Rate.
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.

NoteIf you turn on Maintain Max Influences in the Attribute Editor, the skin weights are not modified until you reassign them by clicking Update Weights.
Dropoff Rate: Specifies how rapidly the influence of each joint on skin points will decrease with the distance from each joint (and the joint’s bone). The greater the Dropoff Rate, the more rapid the decrease in influence with distance. The lower the Dropoff Rate, the further the influence of each joint.

When you bind skin, the Dropoff Rate applies to all the selected joints. Use the slider to specify values between 0.1 and 10. You can enter values up to 100, but values between 0.1 and 10 are ideal for most situations. The default is 4, which provides good deformation effects for most characters.

After binding skin, you can use the Paint Skin Weights Tool to edit the influence of joints in an intuitive manner. For more information, see Painting smooth skin point weights.
Remove Unused Influences: When on, weighted influences that would receive a zero weighting are not included in the bind. This option is useful when you want to reduce the number of calculations for your scene to increase playback speed.

NoteThe Optimize Scene Size Options also let you remove any zero weighted influences from your character’s skin bind. You can turn on Unused Skin Influences in the Remove Unused section.
For more information on the Optimize Scene Size Options, see File > Optimize Scene Size.
Colorize Skeleton: When on, bound skeletons and their skin vertices are colorized so that vertices appear the same color as the joints and bones that influence them.

NoteYou can change the colors of individual joints and bones from the Display > Wireframe Color window.