## ← True Field of View - Interactive 3D Graphics

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Showing Revision 2 created 05/24/2016 by Udacity Robot.

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