For a research prototype we just used a mobile phones acceleration sensors to couple a phone (who uses printed boarding passes) with the tracker. No biometrics

For a research prototype we just used a mobile phones acceleration sensors to couple a phone (who uses printed boarding passes) with the tracker. No biometrics needed. Tracking does not survive the camera context. Considering that there are alternatives you really wonder why they care about biometrics. You could probably also generate other types of markers that are stable without needing sth you have to stick with for the rest of your life...