The origin definition decides which side of the person content appears on

What it is

The same virtual furniture: start with the nose toward the window and the table is on the left; start toward the door and it jumps to the right. Nothing in the scene changed. What changed is the tracking origin frozen at session start — its position, its height, and which way was written as +Z “forward”. Content authored as “a panel in front of the person” lands on whichever side the face happened to point at that instant, including behind and above.

The origin is the first-frame contract of the session, not the later act of unwinding a heading that has crept.

Why it happens

The runtime must nail a coordinate frame into the real room. Two common nails: one on the head (a local origin whose height travels with the wearer) and one on a floor patch (a stage origin whose height is the ground). Content authored in stage space as “a panel two metres forward at 1.6 m” will grow out of an armpit or from behind an ear if the session instead froze a local origin while the wearer was hunched over a phone.

Yaw-zero is the quieter half. The engine writes start facing as world +Z; the author’s “left-hand drawer” is placed against that +Z. Launch sideways on a sofa and the drawer appears in the hallway. Teleport, relocalisation, or a redrawn guardian freezes or rotates that frame again — a new origin, content on a new side.

Height is eaten by the same choice: a standing-calibrated floor origin puts a desk at chest height for a seated wearer; a seated origin buries the same desk in the floor when they stand.

Studying it

Run a placement task: one world-locked scene, vary only launch body yaw, sit versus stand, and origin type (local / local-floor / stage). Ask which side of the body the main panel is on.

Independent variables: origin type, angle between launch facing and the room’s principal axis, posture, whether content was authored at head height or at floor height. Dependent variables: azimuth error of the panel relative to the body midline, whether the first reach hits, verbal agreement on “which side is it on”.

OpenXR’s local, stage, and local-floor are the industrial partition of this contrast. Label conditions by the origin the runtime actually selected, not by headset product name.

Where it stops holding

Head-locked or body-locked chrome does not eat the room origin — it rides with the head or torso; launch yaw only rearranges the world-locked layer. Content that is regenerated every launch and never has to match a room across sessions pays the “wrong-side” cost only inside that sitting. When several people share one stage origin, a late joiner who brings their own local origin will see the same piece on a different side. A lab that always has participants “face the calibration wall, then press start” washes out the crooked launches that dominate daily use.

Applying it

• Author world-locked primary content in stage space, and set +Z from the walkable area and the wearer’s intended facing at session start — do not silently accept the nose direction of the headset’s first frame.
• State whether the origin is nailed to the floor or to the head; do not mix standing-authored and sitting-authored heights.
• Offer two distinct actions: “make forward face me” (yaw only) and “put the content back on that patch of the room” (do not quietly rewrite height).
• How to check: open the same content from three launches — facing the window, facing the door, sitting sideways on the sofa — and record whether the main panel first appears left, right, or behind. If the three disagree, the origin is choosing sides for the wearer.

Related

• Same group: N1.09.1 Yaw drifts over time and needs a recentre entry point · N1.09.3 Panoramic footage is inherently 3DoF; translation cannot be added in post · N1.09.4 Loss of positional tracking needs a degraded mode, not an interruption
• Nearby: N1.02 Degrees of Freedom · N4.04 Room Scale and Safety Boundaries
• Search terms: tracking origin · stage space · OpenXR origin