Because I've played enough FPS games as a kid, and played enough with FOV parameter in their debug consoles to know how 160° FOV looks like on a render :). The FOVO picture is the one that looks normal; the stretchy one is a traditional perspective projection.
(As for why I played with FOV command? Curiosity, plus if you bound a key on your keyboard to set FOV to 30-40 on keypress and restore it to normal on release, you got free sniper scope on every weapon :).)
(As for why I played with FOV command? Curiosity, plus if you bound a key on your keyboard to set FOV to 30-40 on keypress and restore it to normal on release, you got free sniper scope on every weapon :).)