Fig. 8.

The difference between rescaled and original PPVs. The original trajectories and PPVs are shown in blue (departure trip) and pink (return trip) and are the same as in Fig. 6 – here, the elevation is almost unnoticeable, due to the much larger extent of movement in horizontal than vertical direction. The green and teal trajectories/PPV show the rescaled versions of departure and return respectively, where z dimension of the trajectory coordinates was rescaled (stretched) according to the ratio of maximum horizontal and vertical speeds on each trajectory. This provides a clearer visualisation of the shape of each PPV and allows visual identification of segments with the fastest and slowest movement, corresponding to the thinnest and thickest ellipsoids