This is something I have mentioned in the past and it has been present since flyinside first started supporting x-plane. The virtual world warps and bends as you move your head. It is most evident on the periphery of the displays with items close to your viewpoint. The door frames in small GA aircraft and helicopters for example. The ground outside the aircraft also appears to be rising away from you rather than flat. It’s as if the aircraft is in a bowl/depression on the ground or the horizon is in the wrong place. Especially evident when looking out to the side.
I have played around with world scale and adjusted the viewpoint a lot to try and get things to look right. From all of that adjusting I’m convinced either the vertical to horizontal FOV ratio is wrong or there is something about how x-plane uses vanishing points which is causing the issue. EDIT: see second post for a possible third cause.
If I adjust world scale to get proper horizontal scale then the vertical scale is off. Adjusting to have vertical exact throws off the horizontal scale. I thought it may have been fixed in the latest release but after further use I see it is still present. Could the FOV overdraw percentage be a factor?
Has anyone else noticed the same problem? If you haven’t perhaps don’t look for it. Once you see it you can’t unsee it!