...
The transformation contains an optimization which assumes that the "tracker" with which the track coordinates correspond, moves along the longitudinal profile at a pace slow enough to never pass more than 1 point in a single time step, i.e., for each latitude and longitude input time series, only for the first non-missing point the distance to all longitudinal profile points is calculated. After this calculation"calibration", the transformation remembers which profile point was closest for the previous time step, and for subsequent time steps only the distance between to the previously closest profile point and its direct neighbors is calculated, from which the closest profile point is selected.
If the coordinates for at least <minMissingStepsForRecalibration> subsequent time step are missing (NaN), the next non-missing point is treated as the first point in a new time series. By default, <minMissingStepsForRecalibration> will be set to 1. Note that if <minMissingStepsForRecalibration> is set to 0, the distance between all track points and longitudinal profile points is calculated, effectively removing the optimization. For the largest best possible optimization of this transformation, set <minMissingStepsForRecalibration> to the minimum amount of time steps a "tracker" will need to go from one longitudinal profile point to the next.
...