Compass

The Compass internally utilizes the accelerometer and magnetometer to estimate the device orientation in relation to the magnetic north. As the compass is vulnerable to external influences, it is recommended to disable the Compass in the presence of strong magnetic fields.

Characteristics

• Provides orientation in world coordinate system.
• The error in orientation estimation is characterized by an offset between real and estimated device orientation. Typically an accuracy of 10-20° is achieved. In the presence of strong magnetic fields orientation estimation is unusable.
• Pose estimation suffers from noticeable jitter if Compass is used as the only orientation source.
• The orientation is updated with roughly 250Hz.
• Orientation estimation is not responsive and suffers from noticeable delays.
• Requires accelerometer and magnetometer.

Compass Calibration

To compensate the offset between real and estimated device orientation, the compass offset can be calibrated, by one of these three mechanisms:

• Manually specify the compass offset in the Settings.
• Once the Compass Calibration Button in the POI View is clicked, the Compass will behave as if the current heading was north.
• Once an AR-Marker, used for device pose estimation, is scanned, the Compass offset is automatically calibrated.