I was talking with @Khakkis about this the other night and thought I would share, I have been using this for a few year now and found it to work really very well. It uses the Open Track like the smartphone option but uses ‘active beacons’ rather than trying to recognise your face, much more reliable in variable light.
It supports the usual look around but also the head tilt and lean forward and back…
I had one of the PS4 camera head tracking setups for a long time, converted the usb powered hat clip to battery, it’s a great and cheap solution. Swapped to tobii just to be able to play sans hat of headphones if u wanted.
Tobii is great but has a tiny bit of lag that true TrackIR doesn’t, I think if you were using head targeting and take it serious then that is the best of the best.
My first head tracker was an iPhone app duck taped to a BBall cap, it worked and was more imersive than using a mouse!!!