Any chance you can provide a photo to demonstrate this stretch and your video options as well?

That problem look less bad if you place your 3 screen on a straight line... But who does that seriously ???

can you provide a screenshot of your video settings, the "display" tab in particular

Screenshot 9 and 10 have been taken from the exact same location . No zoom, no aim, No nothing. But look how close the building on the right looks when its on the right monitor compared to when its in the center of the screen. No imagine that you are flying and helicopter close to some building... Believe me you gonna crash.

There is your answer. Your aspect ratio is not set correctly. The circle and square provided in the setting not only have to overlap exactly with the underlying circle and square, they also have to look like circle and square and not rectangular and ellipse. Maybe some fiddling required.

You were right about the ratio I was in 12:3 when I should have been in 16:3 which is :
fovTop=0.628318531; 36 degrees
fovLeft=2.094395102; 120 degrees

this is exactly the ratio I have in proportion to my screen setup
I did the maths so it should be squared in game.

But it is not, Plus it feels claustrophobic, Plus it looks even worse, Plus the circle does not look like a circle and it does not align (which I don't think it is supposed to do anyway)

It supposed to align and it supposed to be round, if you don't have that the calculations must be wrong.

Can you give me your FOV settings if you got it right ???

Or your just telling me that I'm wrong and that there's no actual problem without even trying it ?

fov settings are individual to each setup, mine will do no good to you.

http://www.rjdown.co.uk/projects/bfbc2/fovcalculator.php

120 degree = 2.0943951 radians 5760px
x
36 degree = 0.628318531 radians 1080px

which is equivalent to a ratio of 16:3 once converted to width and height

And should not be stretched in any way.

The problem lies in way the engine generates the projection or perspective.

If you have 3 horizontal 16:9 monitor then it should be the same.

That calculator didn't work for me either when I tried to set FOV for ArmA 3 it came out all ugly because my aspect ratio is not standard. I had to use different method http://killzonekid.com/how-to-change-fov-in-arma-the-easy-way/ It is linked to the correct video set up so I doubt this will be any good to you.

I really don't know how to make it work... I really think that there's something wrong with the Engine because I did all the calculation many time and I even build a spreadsheet with confirmation formula just to make sure I was doing it right and it still looks weird and the circle don't align...

Maybe they use a weird formula that I don't know of or something... I really don't know what to do...

Look at the screenshot !

dont play with 3 monitors then ;) thats a bit "OTT"

disconnect side monitors let the game autoconfigure for a single monitor, find that aspect ratio then connect everything back and multiply it by 3. leave fov as if it was for single monitor maybe to start with.

If you got that issue fixed then tell us your ratios and configs or at least send us a screenshot. Because if you never even tried how can you even try to solve that issue.

Got mine sorted out. Had to adjust the top and left fov and I am using equililant to 90 degree FOV and I loose my compass use as it is cut off due to the zooming view in. Still have a bit of a strech going on at the edges but the circle is a circle and the square is square. Arma and other games just have that issue. Using a larger fov will give you compass and zoomed out view but worse stretch at edges and way bad performance due to having to render sooooooo much in frame at once. I just wish BIS would give stock aspect ratio options for three 16:9 aspect displays and 16:10 displays as well in 3 monitor set up.

This issue is almost fixed with the latest version.

I suggest you take a look at DCS World and the way the render triple screen because it does look perfect on there game, which gives me hope.

It is far from fixed, the aspect ratios are not doing anything, you dont gain any extra field of view like you should when using 3 monitors.

almost 2019 and this still have't been dealt with.
I've read any piece on the internet about this and tried 3 FOV calculators, non worked. not one solution found at the internet.