Headtracker glitching on iPhone 6

[ejoebstl]

On iPhone 6, the headtracker occasionally "jumps" between different positions. The problem seems to be related to core motion (it does not happen in pure EKF mode). If the "jump" occurs for a rotation around the vertical axis, it also occurs for the "opposite" rotation, e.g. 180° across.

The glitch could not be observed on iPhone 5 or 5s.

Any ideas or hints for tracking that one down?

[rsanchezsaez]

Hmm, that's weird. I did pretty extensive testing on an iPhone 6 back when I originally released this and I didn't experience the issue.

The CoreMotion mode directly uses the _motionManager.deviceMotion.attitude.rotationMatrix, matrix, which should be correct if there are no bugs within iOS. A possible cause could be CMDeviceMotion getting into a funny state on some circumstances.

Do you have a specific way of reproducing this? Does it happen again after rebooting the phone? On which iOS versions have you tried?

[ejoebstl]

Thanks for getting back!
It happens even after restarting the device. The iOS version is 9.0.

I'll try to isolate the cause or find out how to reproduce. Are there any special signs I should look for?