What is the ideal FOV for a widescreen display user? Ideally, I maintain that the center of the screen should look exactly like the original Morrowind game and the borders of the screen should merely add additional peripheral details.

When Morrowind was originally released (around 2002), monitors had 4:3 (physical) aspect ratio and Morrowind used 75 degree aspect ratio.

Now, most people use widescreen displays at 1680x1050 or 1920x1200 with a 16:10 aspect ratio. 16:9 monitors with resolutions like 1920x1080 are a bit less commonly used (more info here: http://en.wikipedia.org/wiki/Display_resolution)

I'm going to assume only square pixels, which simplifies the calculations. Using oddball resolutions like 1280x1024 on a 16:10 montor is going to confuse things as it involves rectangular pixels.


Under these assumptions, a 16:10 widescreen user (typically native 1680x1050 or 1920x1200) should use

2 * arctan( 16/10 * 3/4 * tan( 0.5 * 75 ) ) = 85.277... degrees

and a 16:9 widescreen user (typically native 1920x1080) should use

2 * arctan( 16/9 * 3/4 * tan( 0.5 * 75 ) ) = 91.308... degrees

Note: in these calculations the functions arctan and tan involve degrees, not radians.
The use of trigonometric functions is clearly necessary because otherwise a wide enough screen would lead to a calculated result above 180, which leads to the nonsensical conclusion that you should be seeing things behind you on your flat monitor. tan(FOV) is also nonsensical as a 90 degree FOV is perfectly valid but tan(90) cannot be computed. Instead it is tan(FOV/2) that should be used. FYI the tangent of 75/2 is simply the ratio of game distance between the center of the 4x3 screen and the side, divided by the game screen-to-camera distance. This distance is simply scaled and converted back to FOV angle for use on a widescreen.

MATHS!!! :ahhh:

That's what I kept trying to tell everyone, but they just laughed at me.

Hey if you guys could check my assumptions that would be great.
I'm worried maybe Morrowind was originally intended to be played 1280x1024 on a 4:3 monitor, which would involve rectangular pixels and complicate things.
I also don't have proof that 75 is the default FOV for Morrwoind. Although it is the default in MGE.

I see a value of 90 suggested for widescreen users, but it will result in visual distortion relative to how Morrowind was originally played. For 16:10 screen users who adopt my recommendation and switch to the computed value of 85.2... they may see a higher FPS. Ignoring the tiny near plane distance, the volume of these users' viewing frustum will drop by (tan(90/2)-tan(85.2.../2))/ tan(90/2) = about 8%.

I'm not sure which formula FPS Opt uses to calculate widescreen, but I think it's clevererer (technical term). If I leave the FOV as 75 and select the 16:9 as the aspect ratio I get exactly the result I want, a slight 'wide angle' distortion at the very left and right edges of the screen, but the vertical looks untouched. This, to my eyes at least, looks a much better simulation of human peripheral vision than the way MGE does it.

Edit: I should add that it seems MGE and FPS Opt play nice, so I just leave the MGE aspect ratio as is and let FPS Opt do it's stuff.

I'm playing @ 1920 x 1200. I don't use the optimizer anymore, but I downloaded it and did some testing. I've heard before that the default FOV is 75. In the old days with a 1280 x 1024 monitor, I used to increase the FOV with the FPS optimizer a bit, around 80 - 85 FOV.

80 FOV: Unnoticeable difference from default.
100 FOV: Seems about right. I think this is about ideal. No obvious fishbowl effect.
120 FOV: The fishbowl effect is distracting, and is obvious even near the center of the screen.

In 2002, common monitor size was between 15" - 17", and probably 1024 x 768. 19" was a relatively new option, and 21" was expensive luxury.

I think your basic math is probably good, but might need a small weighting factor.

erm. what means fov?

Field of View:
http://www.siggraph.org/education/materials/HyperGraph/animation/cameras/traditional_film_camera_techniqu.htm#Field%20of%20View

Essentially it means the width of the viewing angle of a camera or person.

You can alter the FOV in some 1st person games, or in Morrowind with the FPS Optimizer. It widens the view, but when the FOV gets large, a fishbowl effect starts to occur, first at the outside of the view, and then further towards the center as the FOV increases. So it's like staring into a fishbowl, or looking at a reflection of your surroundings in the reflection of a glass ball.

I use 85.
My suggestion is to test different values until you find what you think looks best.