The FOV
From Xtreme3D
The FOV
Field of View | The Field of ViewThe angle (horizontal or vertical), which covers the projection of the 3d scene. In the frame buffer gets only some of the area of the scene - we look at the truncated pyramid visibility (view frustrum), the angle between the two opposing sides which forms a field of view.
In most 2D games it is impossible to speak about the angle of view - it is zero, and the pyramid is a rectangular tube.
The FOV seriously affects the perspective: when large values of the field of view (more than 90) visible object size decreases rapidly with distance. At small values, on the contrary, the visible size of an object is weakly depends on the distance (and it does not depend in the case of ���������������� of projection, i.e. in the absence of prospects - when the field vision is zero).
For understanding the term an analogy might be with a focal length of the camera, which directly affects its field of view.
In real life the horizontal angle of vision is approximately 140 degrees.