A different friend of mine mentioned that when they have talked about cameras in 3d graphics in classes he has taken, they usually build up the model for the projection matrix starting with the idea of a pinhole camera. Seeing as how the diagrams illustrating this concept are usually drawn from the side, he suggested that may be the source of the convention. Sounds plausible to me.

My opinion (which, incidentally, was what caused me to rewrite my engine's camera FOV stuff recently) is to better support widescreen type aspect ratios. If you use horizontal FOV rather than vertical FOV and you change your aspect ratio from, say, 4:3 to 16:9 then you end up seeing LESS vertically rather than seeing MORE horizontally. At least, that's the way it worked for me - and I now seamlessly and easily support widescreen in my engine. Hope this helps.

Quote:Original post by Dranith
Haha, yes I did read the parenthesis wrong. I worked it out by hand and indeed got what you posted above. Sorry about that.

Edit : Ah, I see you posted a derivation as well. Now if you could just tell me why the convention is to use y-fov! =)

hah. did the same thing, my mistake jyk.

Yeah Rompa has what I believe to the best answer: arguably widescreen should expose more horizontally, rather than less vertically assuming the viewer distance to monitor does not change. Of course this is a somewhat subjective decision as well, but widescreen ratios seem to "make more sense" visually, and thus they should probably be the first class citizens, with 4:3 ratios seeing less on the sides. Movies have adopted this convention, and NVIDIA's "XHD" as well.