Eye gaze normalized direction and convert to angle

[Ihshan Gumilar]

Hi,

I am trying to convert gaze direction into angle. However, I cannot find any information regarding the explanation about normalized gaze diretion x, y, and z. 

What does this normalized gaze direction mean ? is it in radian or what ?  is it in the range -1 and 1 ?

Is there a way to convert directly into angle ?

 

Thanks for your help in advance

 

Ihshan