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Reference Frames

Key idea​

ResXR data is mostly reported in Unity world coordinates, but some streams originate in Meta tracking space.

Coordinate space conversion​

OVRPlugin APIs return tracking space (right-handed) data relative to the VR play-area origin. ResXR converts most spatial data into Unity world space (left-handed) using a tracking-space converter:

Conversion notes:

  1. Z-axis flip (right-handed → left-handed)
  2. Rotate by OVRCameraRig rotation
  3. Add OVRCameraRig position offset

Velocities are rotated but not offset.

Special case: hands​

Hand bones are recorded in hand-local space (relative to the hand root), not Unity world.

Tracking origin type​

For BIDS pipeline needs and consistent interpretation, ResXR records the tracking origin type (Meta):

  • EyeLevel / FloorLevel / Stage (From OVRManager / OVRPlugin tracking origin API)

Why this matters​

Your analysis pipeline (and later Motion-BIDS conversion) needs to know:

  • Which reference space is being used
  • What "forward/up/right" means for each stream
  • Whether a stream is Unity world or hand-local