Control Point Weights
CP Weights
Many times when a bone has sole ownership of a Control Point (CP) there is an undesired effect when the bones are rotated to extreme angles as shown above. It is even possible for the geometry to collapse on top of itself. There are several solutions to fix this problem including repositioning the bones, Smart Skin, and now CP Weights.
Original Bone Positions and Ownership
The image above shows a common way to bone a model. Using CP weights each CP's position can be controlled by multiple bones, minimizing skin folds and allowing the geometry to blend along the bones and remain smooth.
Has Falloff
Click on a bone and then select Has Falloff on the Property Panel to turn on CP weighting for this bone.
Bone Weighting Falloff
Notice the bone now as two capsules drawn around it. Any CP that falls within the inner capsule will be controlled 100% by this bone. Any CP that falls within the outer capsule will be partially controlled by this bone. The closer to the edge of the outer capsule the CP lies the less the bone will control it.
Use the Pivot Outer, Pivot Inner, Pivot Scale properties to adjust the falloff of the pivot end of the bone and End Outer, End Inner, End Scale to adjust the falloff of the end (tip) of the bone.
Show Advanced
If show advanced properties is enabled in the [Tools][Options] dialog on the global tab then there will be one additional property called Falloff Type under the Has Falloff property .
Falloff Type
Cubic, Linear, and Channel are the three available falloff types. Falloff is the span between the inner capsule and the outer capsule. The Falloff Type property is the method you would like to use to calculate the CP's weight if it falls within this region. Cubic will weigh the CP using a curve falloff between the two capsules. Linear will weigh the CP using a straight line falloff. Channel will use the curve defined by you. To define the curve use the timeline panel and the "Bone Falloff Curve" property on the model. Define a curve from 0% to 100% on the timeline.
Bone Falloff Curve Property
Bone Falloff Property Channel
Once you have adjusted the falloffs of all desired bones, right click (Control click on a Mac) in the Modeling window and select [Compute All CP Weights]. This will calculate each CP's weight for each bone based on all the bone's falloff settings.
Compute all CP Weights
When a bone is selected all CPs it fully controls will be drawn in the bone color. If the CP is partially controlled by any other bone the CP will have circles around it in the color of the other influencing bones. The order to which color circle is drawn around which is irrelevant and has nothing to do with who has the strongest control of the CP.
Weight Circles
When the model is in Shaded and Bones mode the surface will be shaded in a blended color of the bones that influences it. Notice in the following picture that the model that has had CP weights applied to it has a much smoother transition between the colors.
Weight Gradients
Animating the model with extreme rotations should have a better result now as shown in the first illustration in this document.
Note anytime the influence falloffs are adjusted the CP weights must be recomputed by right clicking (Control clicking on the Mac) and selecting [Compute All CP Weights].
To just calculate the weights of all CPs owned by one bone simply right click (Control click on the Mac) and select [Compute CP Weights].
Edit CP Weights.
To manually adjust CP weights simply group the CPs you wish to adjust while in Modeling mode and then right click (Control click on the Mac) on the group and select [Edit CP Weights...].
Control Point Weights Dialog
From the Control Point Weights dialog any CP that was selected in the group when the dialog was invoked can have its weights adjusted here. Click on the CP to have each bone that influences its position appear in the Bones and Weight list. Select a bone from this list to have the Bone combo box and Weight % edit box populated with its values where they can be edited.
If no bone is selected in the Bones list and a bone from the Bone combo box is selected then that bone will be added to all selected CPs in the list. This allows you to add new influences to CPs.
Select multiple CPs and click "Balance Selected" to have the weights of all CP's that are selected averaged together. When the CP's are all balanced they will all have the same Bone List with the same weights.
Balance Connected has a couple specific uses. When Balance Connected is applied it will balance only CP's selected in the list with other CP's selected in the list whose geometry is connected to one another. One powerful use of this feature is scales on a fishl.
Scales
Weights
In the above images the scales of a fish are shown with weights computed three ways. The first is no weights at all. The scales are 100 percent assigned to one bone. The problem with this is when the fish animates the scales will move in three groups since there are three bones. The second image shows the weights computed using falloff. This gives smooth blending when animated but the scales stretch and shrink and change sizes unlike real scales. The last image shows Balanced Connected Weights. To do this the weight falloff was calculated exactly as before and then all the scales were grouped together and edited using the Control Point Weight dialog. From within the dialog all the CP's were selected and then the Balance Connected button was pressed. This operation averages all the weights within each scale. Each scale now will retain its shape but will be controlled by different percentages by the bones. Notice how much color variation are in the scales showing the influences of the bones.
Click for Movie Click for Movie Click for Movie