Figure A.4.

Density distribution estimation (by Gaussian kernel) of fixation positions in the viewport as a function of the headset's latitudinal rotation (pitch). Below each subfigure is reported the number of fixations sampled in the latitudinal range divided by the total number of fixations ($Rati{o}_N$). $Media{n}_{\delta y}$ informs about the median distance of the fixation positions on the vertical axis to the center of the viewport.