What is the cause of perspective warping in games?

[Forboding Angel]

take a look at this vid http://www.youtube.com/watch?v=3e8HT0gtlPw

What causes this to happen in pc games?

[lurker]

It's not exactly 'warping'; that camera mode just has a wide enough field of view that the screen has to be really close to your face for the perspective to line up.

[Forboding Angel]

So what degree of a field of view is optimal? Is it reletive, or is there an accepted standard? I searched the hell out of wikipedia, but just about everything I found was related to RL photography.

[RogerN]

Most FPS games use a 90 degree field of view. The optimal value is usually a little less than 90, but depends on your monitor size and how close you sit to the monitor. Many hardcore gamers prever higher FOV's. There is a slight competitive advantage since you can see more to the side. I know several guys that like to play at 120.

[Cremuss]

Every quake 3 players set cg_fov to 110 or 120 ^^

[Hoi]

and maxfps to 76, it makes you jump futher, a bug in the quake engine

[Pxtl]

Screens are flat. The principle of a screen is that it is a window into a non-existent world. The problem is how far are you from that window? If you're up close, the stuff around the sides must be distorted. If you're far away, you're looking through a pinhole and only seeing a small angle of the world. Hence, the FOV numbers. The standard is an FOV of 90, where there is no apparent distorition - FOV 0 would be assuming the screen is infinitely far away, and FOV180 would assume that your eyeball is touching the screen (and thus you can't see anything sensible). Many FPS gamers tweak it out a bit higher - you get better peripheral view and a little more intense sensational of speed, but the distortion is more pronounced.

The alternative is a fisheye renderer, in which the screen is assumed to be convex instead of flat... which is inaccurate, but means that higher FOVs can be reached without distortion.

For further discussion, see Wouter Van Oortmessen's "Fisheye Quake" - Wouter is better known as Aardappel, the guy behind Sauerbraten/Cube.

http://strlen.com/gfxengine/fisheyequake/compare.html

[Cremuss]

<HS>

and maxfps to 76, it makes you jump futher, a bug in the quake engine

na. It's not a bug it's a feature =p
The more fps you get, the more you'll be able to get a big jump. 333fps is the best but it has been locked to 125 for everybody ( defrag comp )
</HS>

[KDR_11k]

333fps is the best

Awwww, 666FPS would have been so much more awesome...

[smoth]

forb:
perspective, vanishing points.

we use single point.

the two point that are draw out are drawn out from it at about 90 remember what I told you about paper and points. what happens if you bring the single point of focus closer to the base of the triangle? the angle becomes wider.

[zwzsg]

I do not believe than perspective vanish's points have anything to do with 3D engines. They are tricks for hand-drawing, but do not hold any reality.

[Forboding Angel]

Well here's another really wierd point... Turns out I was right when I told the vendetta devs/peoples that you would need to set the fov to 45 - 60. fov 60 is when it stops warping. I don't understand that though. I have never seen an fps game warp around the sides like that, but in this game fov 85 is unplayable and looks like you're in a fishbowl.

I'm confused. Fov 85-90 is supposed to be non warptastic right? I've never noticed source, or cod4, or nexuiz, or any of that crap warping. WtFork?

[RogerN]

I'm confused. Fov 85-90 is supposed to be non warptastic right? I've never noticed source, or cod4, or nexuiz, or any of that crap warping. WtFork?

It's possible that their engine implicitly doubles the FOV. For example, in the Quake series of games, setting the FOV to 90 means that the entire field of view is 90 degrees. That's 45 degrees to the left and 45 degrees to the right. But some engines may interpret the FOV as being the angle between the camera's direction vector and the side of the viewing window. In that case, FOV 60 would mean 60 degrees to the left AND 60 degrees to the right... which would be the equivalent of FOV 120 in Quake.

[Forboding Angel]

Ahhhh... that would explain why fov 120 in that game is "omgwtf?1"

[lurker]

Strange that you would be able to go so high if it's doubling it, wonder how it runs that through internally... What does 85 look like?

[Forboding Angel]

Fishbowl

[CarRepairer]

You mean fisheye. Like when you look through your door's peephole.

[Forboding Angel]

No fishbowl... as if I had my head in a fishbowl looking out at the world.