Why does the data export contain different lines and timestamps for each eye, marker, etc?

The two eye cameras, although recording at the same frequency (60 Hz), capture images at slightly different timestamps. One analogy to understand this is cylinders firing at different times in an engine, but at the same rate. This is the main reason for the export containing different lines. Also, the scene camera records at 30 Hz, which is why if you export marker coordinates (X1-4/Y1-4), they will be available in frames when the scene camera captured images. D-Lab calculates the Pupil X/Y using coordinates from each eye camera – these are then used to calculate Gaze X/Y coordinates. Both Pupil X/Y and Gaze X/Y are displayed on the same timestamp as the left eye. D-Lab simply records the time at which the data point (in this case frame from one of the cameras) is received.