PointTracker is a plugin for the free head tracking software FaceTrackNoIR which introduces the capability to track a (typically IR-) point model comprising 3 bright points to FaceTrackNoIR, much like the popular free tracking software Freetrack does. It was created as a stable modular alternative to Freetrack, which has some stability issues with newer systems and seems to be no longer actively developped.

This section desribes how the FTNoIR filter work and what the recommended settings for PointTracker are.

Filtering is always a tradeoff between stability, accuracy and responsiveness.

The Smoothing filter in FTNoIR is just a simple average over the last n samples. Since this filter produces input lag no matter how fast the head-movements are, it is recommended to turn it off by setting samples to 1.

In the filter tab, it is recommended to select Accela Filter Mk2 . Accela is a non-linear filter that works as follows:

It looks at the difference between the new raw values new_val from the tracker and the last filtered value old_val and maps this difference via the customizable response function f via:



new_val = old_val + f(new_val - old_val) / reduction_factor

So by setting f(x) = reduction_factor * x, one will get no filtering at all.

If you set lower values for small x, small deviations (usually noise) will get dampened. This results in a dynamic dead-zone around the current position.

The last two points are used by accela to extrapolate for large deviations. So in order to get a fast unfiltered response for large deviations, the line connecting the last two points should have a slope >= reduction_factor.

More aggressive accela settings than the default FTNoIR accela settings are recommended in order to decrease the filtering lag and fully use the potential of point tracking.

My current settings are:

[Accela] Reduction=20 [Curves-Accela-Scaling-Rotation] point-count=4 point-0-x=0.1 point-0-y=0 point-1-x=1.43 point-1-y=2.45 point-2-x=2.0 point-2-y=5.44 point-3-x=2.06 point-3-y=6