Avastar 2.0-beta23

The source of all issues

Animations can possibly affect your Avatar shape while the animation runs. The main reason for this is that sliders and animations both are allowed to modify bone locations (translate). This can cause a conflict:

1. The user edits the Shape by using the appearance editor.
2. The Shape sliders place the bones at specific locations.
3. A creator publishes an animation with Translation components.
4. User plays the animation on top of their shape.

Result: The sliders and the animation concur about where the bones shall be placed. Here is a table for what sorts of transforms are possible for sliders and animations:

In many cases the dependencies between sliders and animations are only small or at least acceptable, so you may be fully OK with that. However the shape changes introduced by animations depend on the Shapes (of course). In theory an animation plays exactly as intended only for the specific mesh and on the specific Shape for which it has been made. In practice the problems are less apparent, but still there.

However things are not as bad as some people have indicated in the past weeks. Some sliders do not change the bone locations but only their scale. And animations do not necessarily need to move all bones. Here are 2 videos from Medhue Simoni which demonstrate what you can do with the sliders:

However, we can never have a perfect system. But we can still try to improve it. The Bento team has taken a closer look into this topic and optimized the sliders to  improve the cooperation of shapes and animations.

The Avatar Definition files (skeleton and appearance sliders) has been reworked with 2 goals in mind:

1. Optimize the system to allow an easy creation of good reusable animations.
2. Minimize the influence of animations on the character shape.

The main changes where to move the bones to less problematic locations and to use Scale instead of translation in the Appearance sliders wherever this was possible. In the following section you find a summary of all made changes.

The Wings

The Avatar height slider now applies offsets to the Wing bones. The slider intentionally uses only Offsets and no scale. This makes it possible to disable the slider influence for cases where the Wing bone chains are used for different purpose.

The Tail

The Avatar height slider now applies offsets to the Tail bones. The slider intentionally uses only Offsets and no scale. This makes it possible to disable the slider influence for cases where the tail bone chain is used for different purpose.

The Eyes

Alt Eyes parented to mFaceRoot

In the original Bento proposal the alt eyes have been added to the exact same location as the system eyes and they have been parented to mHead.

Now the alt eyes still are located at the same location as the eyes, but they have been parented to the face root. This has been done to better support creators of non human heads.

Alt Eyes are auto animated

Scaling for custom mesh eyes (Eye Size)

When you weight your custom eyes to the mEye or the mFaceEyeAlt bones, then scaling the eyes with the eye Size appearance slider now also affects the size of custom mesh eyes (right side of image).

Left: Custom eyes, no Scaling (current behavior)
Right: Custom Eyes, with Scaling (new behavior)

Note: The Eye Size slider adds a small forward/backward movement of the eye joints. (grey in the image).

However the eyelids do not follow the Eye joints (green in the image). This results in a small dependency of the eyelid movement (green circles) on the slider value for the Eye Size. The grey circles show the ideal curve for the eyelids.

Left: Slider = 0, Right: Slider = 100

Eye Lid Joints (mFaceEyelid…)

The Eyelid joints have been moved to match the Eye joints. This was made to create more consistent Eyelid animations based on rotations only.

The visual length of the mEye and mFaceEyeAlt bones have been reduced to roughly match the size of the eye lid bones.

The Jaw (mFaceJaw)

The Jaw joint was moved to an anatomically more correct location. This was made to provide better movement of the mouth area when opened by using rotation-only animations.

The Jaw bone was previously moved around by a couple of sliders. This is no longer the case. The bone now remains stable below the Face root bone.

The Jaw Angle (mFaceJawShaper)

If we have only one Jaw bone then we have to use the bone for shaping and for animation. Because of this a new Jaw Shaper bone was added to separate the Shaping from the Animation.

The new bone moves up/down with the Jaw Angle slider as indicated in the image. It is parented to the face Root.

Side note from the developers:

The Jaw Shaper bone can be parented either to the Jaw or to mFaceRoot. Both solutions work but parenting to mFaceRoot has 2 advantages:

1. If we parent to the Jaw bone, then you can see in the left image how the Jaw Shaper rotates together with the Jaw (when mouth opened). This can cause a sinking of the neck into the mesh, see between the jaw and the neck. Of course this depends largely on how the neck and jaw have been weighted. When the Jaw Shaper is parented to the Face root (right image), then the bone remains at its position independent from the Jaw rotation. Hence parenting to the face root seems to be the more stable solution.
2. The Jaw Shaper bone can be easy reused for different purposes, like for example unicorn horns. So the decision to parent to mFaceRoot seems to make the system more flexible.

(This note was added by Matrice)

Lower Teeth (mFaceTeethLower)

The lower teeth are now parented to the Jaw bone. This was made to provide anatomically correct behavior.

Note: Now the lower part of the face (chin, lips, teeth) is parented to the Jaw bone, so when you move the Jaw bone the lower part of the face follows in a natural way.

Lower Lips parented to lower Teeth

This substantially simplifies the slider definitions for the bones which influence the mouth. The benefit is that mouth moving sliders now only need to adjust the teeth bones. This in turn removes any translation parts from the lips and so it makes animating the lips much easier.

Upper Lips parented to upper Teeth

Simplifies the slider definitions for the bones which influence the mouth. The same benefits apply as described above.

More about Lips

The Lip joints have all been moved to the Avatar symmetry line (x=0 in Blender y=0 in Maya) This change improves rotation only animations of the lips.

In the original skeleton the lip corners move sideways when the bones are rotated around the Z axis. In the new Skeleton the LipCorner bones have been crossed. Now the lips move sideways and slightly backward (better match to the curve of the mouth) when the bones are rotated.

This change was made to simplify the creation of reusable mouth animations:

Green: Lip Bones (Upper and Lower)
Red: lip corner bones

The Crossed bones Allow better quality Rotation Animations

Nose Size and Nose Width

The Nose size and Nose Width have previously been controlled by moving the mFaceNoseCenter, mFaceNoseRight and mFaceNoseLeft bones. This has been changed to scale the nose center bone. This change allows to animate the nose independent from its size.

Scaled Nose

Head Length

Originally Bone offset was used to shift the teeth forward/backward. The Teeth Bones now use scaling to get into position.  The new behavior is much more comparable to what the system character does:

Head Length: 0 Teeth are compressed

Head Length: 100 Teeth are expanded

Egg Head

The Egg Head Slider can not be set up to reproduce exactly the same changes on Custom meshes as it does on the System Character. To get this done we needed at least one more bone on the top of the head. However after a lot of time and experimenting the custom meshes now look at least somewhat comparable to the system character:

Tongue Bones moved upwards

The Tongue of the system character is placed very deep inside the mouth, well below the lower teeth. Originally the tongue bones where adjusted to the system tongue. But this looked somewhat wrong.

Now the tongue has been moved upwards, see image (right). It is unclear if this is a better choice or not. Feedback for this is wanted.

Tongue where it was originally placed

Tongue Rest pose shifted upwards

Tongue Parented to Lower Teeth

The tongue should move along with the mouth for the mouth shift slider and the mouth position slider. Therefore the Tongue Base has been parented to mFaceTeethLower (ionstead of the original mFaceJaw).

Additional Sliders for Eye Brows (Hair Style Editor)

Following Hair Style Sliders have been attached to the Bento Bones:

• Eybrow Size
• Arced Eyebrows
• Lower Eyebrows
• Pointy Eybrows

Other modifications

• minor tweaking of the lips (lip fullness, thickness, ratio now more appealing)
• Lip Cleft Depth now mostly based on Scale
• Chin Depth now only uses the Chin Bone
• Wide Eyes now uses scale
• Egg head reworked (made much less complex)

Posing Sliders and Shaping Sliders

While working on the changes above it turned out that some sliders seem to be more useful for defining specific poses like the upper eyelid fold slider. While other sliders are purely made for changing the Shape like the head size for example. It looks like the Posing Sliders are more troublesome when combined with animation.

Here is a list of Posing sliders which should not be used for shaping the character if the user intends to apply facial expression animations:

• Outer Eye Corner
• Upper Eye Lid
• Mouth Corner

While those sliders can work with animations like all other sliders do, they tend to add trouble at times, especially when used with other sliders in combination and when using extreme slider values. Then animations can possibly add distortions here.

Note: Some have proposed to simply remove those sliders to avoid confusing users and creators. For now the developers decided to keep the support for those sliders available since Animators have the choice to disable those sliders simply by not weighting their creations to the related bones.

Posing Bones and Shaping Bones

We also seem to have Bones which are dedicated to be used for Animations only (not weighted), while other bones are weighted, but mostly used for Shaping. Here is a list of affected Bones :