I've made many posts about issues like this in the past and i would just link you to them but i cannot find them - i think they have been deleted! I was not aware this forum deleted old topics but if it does that's kind of unfortunate as it means we are going to lose a lot of useful information and possibly content.
Things like this could do with going in some kind of FAQ as they come up a lot.
Anyway, what you are experiencing is because GPL uses a horizontal
FOV value. As you have changed aspect ratio, you have effectively, according to GPL, shrunk your vertical field of view, as the vertical aspect is smaller in comparison to the horizontal.
In fact, even 1280 * 1024 is not the aspect ratio that GPL was designed for, it would have been designed for 1280 * 960 instead.
This means that with a 5:4 aspect of 1280*1024 you will see slightly more
vertically than originally intended.
That said, i would encourage a more realistic FOV anyway, as unless you have an extra-ordinarily large screen then the default FOV in GPL is way too high!
This distorts your perception of distance and height, making tracks look flatter and things look further away than they are.
Can anyone help me find the old topics where i posted about this? They would be interesting for reference but according to my profile, it only lists posts back until mid 2013 :/
The posts are not deleted but for some reason you cannot search your own posting history that far back anymore as it seems broken - no idea why??
Here are (at least some of) the topics - there might be more but since i can't search really, it's hard to find them.
So, to match up with the vertical area of a 4:3 aspect you would use a FOV value of 94.
However if you want to match up with the same vertical area you had with your 5:4 aspect ratio, you should use a FOV of 98.
For how i came up with these numbers, see the topics i have linked.
To be honest though, i really wouldn't recommend driving with either of these FOVs if your screen is small (and/or far away). Mind you, considering you work building simulators like i've done i guess that isn't exactly news to you either. Of course, unless you have a gigantic screen it is always a compromise between realistic FOV and being able to see enough of the world around you.
Also, GPL only supports 1 flat surface for rendering, which is not ideal for triple-screen support. This means side screens should be arranged in one flat plane. Sims like Assetto Corsa, Rfactor 2 and iRacing, however support separate rendering on multiple surfaces, which is good!
Edited by one2fwee, Jul 27 2014 - 04:24 PM.