FOV Tutorial - very useful for triple screen gamers

[FS~Phat]

Someone asked me in another forum why the game gets bent on a triple monitor setup and I put this together to help explain it.

Many people comment on the distortion of a triple screen setup when watching it on a youtube video or screen shot. The fact is, for the most part, especially in Track-IR enabled games it adds depth to the players perspective and you dont usually notice the distortions in game because they are in your peripheral vision. Co-incidently, this is actually a good thing because it make the FOV or perspective feel more natural and comfortable. Note this is only the case if you are the player actually sitting in front of the game playing it, its completely different when viewed on a conventional monitor, heck even a person standing right beside you would think gee that looks weird!!!!! BUT once you sit in front of a triple screen setup, as long as you have the FOV set correctly its an absolutely amazing experience that cant be described. It has to be experienced....

Anyway on to my short little tutorial...

Pincushion distortion is one of the side effects of having an increased field of view. Much like a fish eye lens on a camera, the wider the FOV the greater the distortions.

The only way around this really is to reduce your horizontal FOV which unfortunately reduces your vertical FOV at the same time in a lot of older games (HOR-), so for some games it just makes them feel too claustrophobic if you loose too much vertical FOV.

The trade off for reducing FOV is, that while it can reduce the pincushion effect, you arent then really getting the full benefit of the wider view and it often feels uncomfortable. Most games these days are HOR+ which means vertical FOV is preserved even if you increase your resolution by using triple screen resolution. The side effect of this is often more exaggerated pincushion. Some games even have distortion on a standard 1920x1080 display because of the default FOV, this is by design to make them more comfortable to watch. (watch the video below for an explanation)

The other factor that effects this is camera perspective which also interacts with FOV. Most games are written with a fixed camera perspective. That is... if you change the FOV you cannot change the camera persective (position) in order to reduce or remove the distortion.


How focal length affects perspective: Varying focal lengths at identical field size achieved by different camera-subject distances. Notice that the shorter the focal length and the larger the angle of view, perspective distortion and size differences increase.

taken from http://en.wikipedia.org/wiki/Angle_of_view

Also check these out!

http://en.wikipedia.org/wiki/Field_o...in_video_games

Cool video tutorial on Game FOV >>> http://artsygamer.com/fov-in-games/

http://unity3d.com/support/documenta...ss-Camera.html

Hopefully by the time you've read and watched this you will understand how to set your FOV properly for your screen size and seating distance. (including for surround and eyefinity users!) Now you know why I love playing IL2 and CoD in triple screen resolution!

[von Pilsner]

On flight & racing games I don't really mind the stretch on my side monitors, I mostly use them for peripheral vision. But thanks for the info (I am just using SoftTH so no CloD Triplehead for me yet).

My budget setup....

[phoenix1963]

Originally Posted by FS~Phat

... Most games these days are HOR+ which means vertical FOV is preserved even if you increase your resolution by using triple screen resolution.

Ah... I think you've answered something that has always puzzled me: so am I right in saying in HOR+ the devs change the "film" (or the pinhole) position to keep the vertical FOV constant? That kind of means slightly moving in a flight sim.

56RAF_phoenix

Duh - I just thought about it, it means they keep the film position the same.

But

Originally Posted by FS~Phat

...Pincushion distortion is one of the side effects of having an increased field of view. Much like a fish eye lens on a camera, the wider the FOV the greater the distortions

is surely wrong. In a correctly rectilinear projection you should see no distortion as long as you are viewing the monitor at the right distance and the FOV angle is less than 180 degrees.