Compass Errors in Mobile Augmented Reality Navigation Apps: Consequences and Implications

Augmented reality capabilities on smartphones have led to the development of mobile Augmented Reality (mAR) navigation apps. Whilst some mAR navigation apps annotate navigational points of interest within the camera image, mAR compass apps add only a compass rose and bearing to the image, enabling the device to function as a hand bearing compass. Compass apps do not attempt registration of the camera image, so these apps allow observation of the errors affecting smartphone magnetometers. This paper presents compass deviation (error) curves and offset errors for mAR compass apps on 17 mobile devices. The magnitude of deviation error measured (typically 5-10 degrees) and the apparent transience of compass calibration, over periods of less than an hour, cast doubt on claims that the apps are equivalent to professional navigation compasses, and suitable for navigation use. As an mAR navigation app is unlikely to achieve reliable registration in an open-field context such as yacht navigation, the deviations observed also raise serious questions about the reliability of mAR navigation apps, and identifies real safety concerns for the use of such apps. The paper concludes by speculating on interface designs for mAR navigation apps that could mitigate compass errors in mobile devices, identifying also some issues that require further investigation.