Hi @ayaataya, there is no precise means by which we map the head position to screen position but you could take the following example as an approximate guide that should hopefully point you in the right direction.
Take for instance you have a screen of resolution 1280 x 720 and you are trying to get the estimated (x,y) of gaze on screen based on the head movement variables:
x: yaw (-45 deg) = 0 , yaw (+45 deg) =1280
y: pitch (-45 deg) = 0 , pitch (45 deg) = 720
Of course, this is necessarily rather rough but it should allow you to combine with gaze data, although it’s not clear why you would need this as the gaze location will be reliable regardless if the head rotation ‘agrees’ with it or not.
However, hopefully the above tip should be what you are looking for! Best Wishes 🙂