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Full-Body Tracking

VRChat supports additional tracking points using the HTC Vive Trackers. These work with the Lighthouse ecosystem to permit these two additional modes of motion capture:

  • Four-Point (4PT): Tracking headset, two controllers, and one hip tracker
  • Six-Point (6PT): Tracking headset, two controllers, hip tracker, and one tracker on each foot

At this time, VRChat supports a maximum of three additional trackers in addition to the headset and controllers. VRChat does not officially support any other method of Full-Body Tracking.

Experimental Implementation

This system is experimental and is subject to change or overhaul that may deprecate or modify previous behavior! If you're using this system, pay close attention to updates to ensure you are adapting to new behavior and requirements.

Using Full-Body Tracking in VRChat

When you boot-up VRChat with the required trackers paired with SteamVR, it will automatically detect that you are in "Full-Body" mode. Once loaded in, your avatar will be in a T-Pose, and you will have small spheres on the points where your trackers are located. This is called Calibration Mode.

Be careful while calibrating!

Make sure you aren't going to walk into a wall or object while calibrating! If your model is in an odd spot to calibrate, move into a better position, open your Quick Menu and click "Calibrate". This will reset the process.

To Calibrate, it is easiest to follow this procedure.

  1. Enter Calibration mode by booting into VRChat while wearing Full-Body tracking, changing to a new avatar, or clicking the "Calibrate" button in the Quick Menu.
  2. Align yourself with your avatar so you're "inside" of it.
  3. Align your feet with your avatar's feet using the spheres. If your legs are too long on your avatar, this may appear as if are putting your feet in your shins. That's OK, but you'll be on "stilts".
  4. Align your hip tracker with the approximate position of your tracker on your own hip.
  5. Align your arms with your avatar's arms.
  6. Look directly forward! Ensure your viewpoint is in roughly the right position. If it isn't, you might want to try adjusting your "User Height" in Settings and then restart calibration. This occurs when the avatar you're using doesn't have the proportions set right. This isn't ideal, but works for avatars that aren't proportioned very well. If you do adjust your User Height before calibration, set it back to your real height after calibration is complete.
  7. Click both Interact buttons (typically Trigger) on your controllers simultaneously.

Congratulations, you are now calibrated for Full-Body!

It actually isn't required to line up your hands and arms, just the three tracking spheres and your head. However, it does help ensure your pose lines up and that your proportions feel right.

Rigging Requirements

There are special considerations if you are using Full-Body tracking. There are several recommendations that will ensure that your avatar works well when using Full-Body tracking. If you are using an avatar that hasn't had these refinements/checks performed, you may run into odd behavior.

First, a short glossary:

  • Bone Head - The bone's position. In Blender and most other 3D software, there is a Head and Tail to any given bone. Unity only uses the "tail" or "length" of a bone to determine the rotation of the bone transform. The Head determines the location of the bone transform.
  • IK-driven Bone - Any bone that is mapped in the Mechanim Rigging Configuration screen.
  • Bone Roll - The rotation of the bone along its local Y (up/down) axis.

Full-Body Tracking works best when:

The avatar being used is proportional to a typical human being in regards to limb and torso length. This is not a hard requirement, but it is ideal. If your limbs are disproportionate, you may experience behavior like "arm pull" (your avatar's arms are too short), "stilts" (your avatar's legs are too long), or other strange behavior. You may also have trouble aligning your viewpoint when calibrating if your general Legs>Hips>Spine>Chest>Neck>Head chain proportions are off.

The avatar's rig does not deviate greatly from the example rig given in the SDK named tpose-new.fbx.

"Roll" on all IK-driven bones should be set to zero. In reality, it doesn't really matter what value this is-- as long as all IK-driven bones have the same value.

There are no "Full-Body Hacks" in use such as flipped hips, extra leg bones, zero-length or unweighted necks, or other similar changes. These changes can have greatly detrimental effects to rig behavior, and will eventually break with future Full-Body Tracking changes. These rig "hacks" are optionally applied by "Cat's Blender Plugin". You should not use these!

Your User Height is set properly in Settings, and you do not crouch while calibrating. However, adjusting your User Height up and down a few inches before calibration (and then resetting back to your actual height after calibration) may help with your viewpoint being off in avatars that aren't proportionally accurate.

The distance between bones is greater than zero. You shouldn't ever stack bones on top of each other when they're part of the IK-driven armature and are parented/children of each other. This is especially important for the Hip>Spine>Chest>Neck>Head chain!

The bottom of your hip bone should be above the top of your upper leg bones. The Hip should always be above the top of the leg bones!

Move the hip up above the line established by the two upper leg bones.

Move the hip up above the line established by the two upper leg bones.

Keep in mind that Unity does not care about the "tail" or "length" of a bone as described in Blender and other 3D software, aside from using it to determine the rotation of the bone transform.

There is a very slight bend in the knee and elbows. This is required for the IK solver to operate properly. The bend can be extremely small, but it should bend "dominantly" in the appropriate direction. The bend for the elbows should be towards the back of the rig, and the bend for the knees should be towards the front of the rig. In other words, the corner formed at the elbow by the rig bones should always be pointing to the back, and the corner formed at the knee by the rig bones should always be pointing forward. Additionally, your legs should not be buckled inward-outward when viewed from in-front.

Here's some examples of what you should be aiming for:

Orthographic Side/Front View. Example for Leg bones. The bone below the Lower Leg is the Ankle/Foot.

Orthographic Side/Front View. Example for Leg bones. The bone below the Lower Leg is the Ankle/Foot.

Orthographic Top View. Example for Arm bones.

Orthographic Top View. Example for Arm bones.

Updated 5 months ago

Full-Body Tracking

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