We'd say the view of the bird is pretty distorted. Really the problem is that
you're not sitting close enough to the screen. It's sort of like being
overweight. I could instead say I'm not dense enough. If I was denser, then I'd
look thinner. Think of what the field of view represents. When you look at your
monitor or tablet or mobile device, you're a given distance away from it. The
screen itself is a certain height. This forms a real world field of view angle.
A window on your screen is your window into a virtual world. Say this window in
the real world has a 20 degree field of view for your real world eye position.
If your virtual world also has the same field of view, you won't perceive any
distortion. Objects toward the edge of the screen might look distorted if you
were to back away from the screen. But at your current eye position, the field
of view is perfect. The image is warped a bit in projection. But your eye is
seeing the screen at a tilt that compensates for it. The formula for height for
a given field of view and distance from the screen is height equals 2 times
tangent of the field of view divided by 2, don't forget to use radians, times
the distance. As the field of view increases, the tangent value increases, and
so the height of the monitor increases. Increases. What tends to happen in
video games is that the designer cranks up the virtual world's field of view so
that the players can see more of what's happening around them. This can
certainly lead to a more playable game, but this is also where the distortion
comes from, from the fact that the virtual field of view doesn't match the real
world field of view. If you moved your point of view so that you were at the
apex of the virtual world's frustom right here, the virtual world would appear
undistorted. Of course it might actually all be blurry at this distance, or you
might get a massive headache, but that's the theory.