Sansar Skeleton Skinning Details

Sansar skeleton and skinning details

This article provides detailed information on the joints of the standard Sansar skeletons and provides tips on how to best skin the skeletons when creating custom avatars and rigged clothing.

Note that exporting an avatar from Blender requires non-default export settings. See Exporting custom avatars from Blender for full details.

Avatar skeleton files

Sansar's avatar skeleton files can be found in the article: Avatar reference files.

Joint details

The following joint information is for all the joints in the full resolution skeleton. The mid and low resolution skeletons have minimal face joints and do not contain some of the listed joints below. But for those joints that do exist in the mid and low resolution skeletons, the information is still the same.

Body joints

The core animation joints. All avatar meshes should be hooked up to these joints in order for them to deform correctly when animating. Depending on the location of the mesh, only a certain subset of joints may be needed. For example, pants should only need to be skinned to all the lower body joints.

Bone Names	Bone Names
Central body joints pelvis spine1 spine2 spine3 neck head L_clavicle R_clavicle
Left arm joints L_shoulder L_elbow L_wrist L_shoulder_twist1 L_shoulder_twist2 L_wrist_twist1 L_wrist_twist2 L_olecranon_twist1	Right arm joints R_shoulder R_elbow R_wrist R_shoulder_twist1 R_shoulder_twist2 R_wrist_twist1 R_wrist_twist2 R_olecranon_twist1
Left leg joints L_hip L_knee L_ankle L_ball L_hip_twist1 L_glute_twist1 L_kneecap_twist1	Right leg joints R_hip R_knee R_ankle R_ball R_hip_twist1 R_glute_twist1 R_kneecap_twist1
Left finger joints L_index_01 L_index_02 L_index_03 L_middle_01 L_middle_02 L_middle_03 L_pinky_00 L_pinky_01 L_pinky_02 L_pinky_03 L_ring_01 L_ring_02 L_ring_03 L_thumb_01 L_thumb_02 L_thumb_03	Right finger joints R_index_01 R_index_02 R_index_03 R_middle_01 R_middle_02 R_middle_03 R_pinky_00 R_pinky_01 R_pinky_02 R_pinky_03 R_ring_01 R_ring_02 R_ring_03 R_thumb_01 R_thumb_02 R_thumb_03

Face joints

Skinning to the face joints is only a requirement if you want to have animated faces. If your avatar has a mask or helmet, all these joints can be ignored and only the only the "head" joint needs to be used.

With the limit of only 4 joint influence per vertex, it becomes very complicated to do a smooth skinning spread between all the face joints. It is easiest to only skin to a subset of all the face joints.

For example, if you want a more simplified animated face such as just a flapping mouth and darting eyes, then only the "L_eye", "R_eye", and "jaw" joints need to be used.

If you want to apply facial animations, we highly recommend using the high resolution skeleton as it contains all face joints. If you are not interested in applying facial animations, the mid and low resolutions are some alternatives with less face joints.

Bone Names	Bone Names
Jaw Area Joints jaw	For a simple flappy jaw look, only the "jaw" joint working in conjunction with the "L_lip_corner" and "R_lip_corner" joints listed below are needed.
L_jawline01 L_jawline02
R_jawline01 R_jawline02
Chin Area Joints chin chin_under	Only fine detail meshes would need to be skinned to the chin joints.
Mouth Area Joints lip_upper_center lip_lower_center lip_under	The mouth area has the most complex setup on the face. There are fewer ways to only using a few select joints because they all depend on each other to work. If you want to forego explicit lip animation and keep to a simple flappy jaw setup, then using the "jaw" joint in conjunction with "L_lip_corner" and "R_lip_corner" should be enough.
L_lip_upper_mid01 L_lip_upper_mid02 L_lip_lower_mid01 L_lip_lower_mid02 L_lip_corner
R_lip_upper_mid01 R_lip_upper_mid02 R_lip_lower_mid01 R_lip_lower_mid02 R_lip_corner
Nose Area Joints nose_base nose_bridge	All these joints can be skipped if there is no need for small details such as nostril flares.
L_nasalis L_nostril
R_nasalis R_nostril
Left Eye Area Joints L_eye L_eyelid_upper01 L_eyelid_upper02 L_eyelid_lower01 L_eyelid_lower02 L_eyelid_corner_inner L_eyelid_corner_outer L_eye_upper L_eye_lower L_eye_lateral	If only eyeball rotation is needed, then only skin to the "L_eye" and "R_eye" joints.
Right Eye Area Joints R_eye R_eyelid_upper01 R_eyelid_upper02 R_eyelid_lower01 R_eyelid_lower02 R_eyelid_corner_inner R_eyelid_corner_outer R_eye_upper R_eye_lower R_eye_latera
Forehead Area Joints forehead_center L_forehead R_forehead Between Eyebrow Area Joints procerus Left Eyebrow Area Joints L_brow_inner L_brow_mid L_brow_outer Right Eyebrow Area Joints R_brow_inner R_brow_mid R_brow_outer	The forehead and eyebrow joints cover the areas above the eyes. These joints are used when the character does expressive eyebrow motions.
Left Cheek Area Joints L_cheek L_levatorLabii L_risorius02	For proper smiling animations, the cheek area joints are needed.
Right Cheek Area Joints R_cheek R_levatorLabii R_risorius02
Ears L_ear R_ear Tongue tongue01 tongue02 tongue03	There are very few ear animations, so skipping the ear joints isn't a big deal. The tongue joints are only needed if there is a tongue in the character.

Extra joints

These joints are not used in the default animation set that exists in Sansar's avatars, so skinning to them will not yield any results. But they can be animated for custom emotes. Example: Skinning wing meshes to the "L_wing_ATTACH" and "R_wing_ATTACH", and then flapping them in a custom emote animation.

Bone Names
Chest Joints L_chest R_chest	Not used in the default animation set, but would allow for secondary chest motion in custom emote animations.
Toe Joints L_bigToe_01 L_indexToe_01 L_middleToe_01 L_ringToe_01 L_pinkyToe_01 R_bigToe_01 R_indexToe_01 R_middleToe_01 R_ringToe_01 R_pinkyToe_01	The toe joints aren't animated in the default animation set because it is expected that the avatars would be wearing shoes. But a custom character can be barefooted and have custom animations that makes the toes wiggle.
Attach Joints world_ATTACH locomotion_ATTACH pelvis_ATTACH L_thigh_ATTACH R_thigh_ATTACH head_ATTACH L_forearm_ATTACH R_forearm_ATTACH L_shoulder_ATTACH R_shoulder_ATTACH spine3_ATTACH L_wing_ATTACH R_wing_ATTACH	Accessories would be a good use of ATTACH joints. Example: Hook up a halo to the "head_ATTACH" joint. Then during a custom emote animation, spin the halo around. In the future these ATTACH joints will be even more useful when all animations for the characters can be overwritten.

Support joints

These support joints are only used to support the animation of the body and face joints. They do not need to be hooked up to any meshes since it is their child or related joints that should be getting all the skinning data.

Face Support Joints

• L_eyelid_top

• L_eyelid_bottom

• R_eyelid_top

• R_eyelid_bottom

Other joints

These joints are for other purposes outside of core animation and shouldn't need to have any meshes skinned to them.

• Locomotion_Vector

• root

• L_grip

• R_grip

• camera_ATTACH

Skinning details

Skin bind settings

• 4 Max Influence

• Linear Skinning Method

Skinning examples

Auto-twist Arms:

One thing to keep in mind is that when the skeleton gets imported or referenced into a 3D app, the auto-twist joints are not hooked up in a way that will look correct. But if the skinning on those joints looks similar to the examples, then they will import into the engine and look good during in-game animations.

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Pelvis/Thigh Area:

What makes the pelvis and thigh area a little more complex is the glute_twist1 bone that helps with maintaining volume as the legs are rotating back and forth. That particular bone should only cover a small specific area.

Like the arms, the thighs also have an auto-twist that will help maintain a smoother look as the legs are twisting. Unlike, the arms, the thighs only require 1 twist bone.

Also like the arms, the thigh auto-twist and glute_twist1 is not hooked up during import into a 3D app. So they will not look correct until imported into the engine.

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Elbow and Knee:

These support joints are solely for the purpose of helping the knee and elbow maintain better volume as the lower legs and forearms are bending.

These are also not hooked up during import into a 3D app and will require import into the engine before results can be seen.

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