Why head trackers drift, and how to reduce it

At the end of a long drive you may notice that the in-game view has moved a few degrees to the left or right even though you're looking straight ahead. This is called drift. Every head tracker that measures movement with a sensor instead of a camera shows it to some degree. Here is why it happens and how PiHead Tracker reduces it.

Where does drift come from?

The gyroscope in the device measures how fast your head is turning. The app adds up that speed over time to work out where you're looking. Even when it's perfectly still, a gyroscope doesn't read exactly zero; there is a tiny error of around a hundredth of a degree per second. You can't feel it on its own, but over several minutes it can add up to a few degrees.

The error isn't constant either. It changes a little as the device warms up, which is why drift is most noticeable in the first minutes and when the device has come in from a cold place.

Why don't pitch and roll drift?

Next to the gyroscope, the device has an accelerometer. It sees the direction of gravity, so the app can constantly correct how far your head is tilted forward or sideways. Gravity doesn't help with turning left and right (yaw): when you turn your head, the direction of gravity stays the same. That's why drift almost always shows up as left-right movement.

How the app corrects it

• Learning on the desk: while the device is still, the app measures the gyroscope's current error and subtracts it. That's why leaving the device on the desk for a minute before playing helps.
• Learning during use: when your head stays still for a few seconds, the app updates the error very slowly. This is deliberately cautious so that slow head movements aren't mistaken for drift.
• Auto recenter: while you look near the center, the app pulls the center very slowly towards your view direction, so the remaining small error disappears without you noticing. It stays out of the way when you check a mirror or look over your shoulder.

Practical tips

• Leave the device on a flat surface for a minute before you start playing.
• If it came from a cold place, let it warm up for five minutes, then run Gyro Calibration in the app.
• If drift is noticeable, raise Auto recenter from Light to Medium.
• Get used to the recenter shortcut (default Ctrl+Shift+R) or a HOTAS button. Recentering now and then is the quickest fix in long sessions.
• Make sure the device sits firmly on the headset. A loose mount increases drift and jitter.

If drift still exceeds a few degrees per minute after these steps, copy the support report from the Support Assistant and send it to us, and we'll take a look together.