Fisheye Correction

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Tudz

Supreme [H]ardness
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Jun 15, 2008
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G'day all,

Is there any tools for correcting the fisheye effect when using Eyefinity with a high FOV?

I dont have Eyefinity, but I was using it at a friend's house and whilst I thought it was pretty cool, 2 things really bothered me, firstly the bezels when in portrait mode (though in landscape I didn't notice them) and the fisheye effect really distracted me. Another friend told me a non ATI 3rd party had created a fisheye correction tool, but I can't find it with google searches (just brings up fisheye correction stuff for adobe things).

I'd really like to get an Eyefinity set up, but at the cost of it ($500AUD for a 5870 + at least $500 for 2 more 24" screens) I really want it to work properly. Playing it on my friend's PC just reinforced the thought that I really want Eyefinity, but also that the flaws will really piss me off :p

Cheers,
Tudz
 
There are a couple of things you have to understand about how game cameras work. The "distortion," as you call it, is 100% optically correct.

1. Game cameras use one-point-perspective, and place that point dead-center. Because of this, a given FOV can only be viewed properly when looking at the very center of your screen.
2. A given FOV can only be viewed properly when sitting a certain distance from your screen. This is dependent upon the physical size of your display.

I'm sure you've seen what happens when you turn the FOV up too high on a 4:3 monitor, everything goes fisheye. The solution is to sit closer, or turn the FOV down.

Keeping in mind that you should only ever be looking directly at the center screen because of the fixed one-point perspective (using the sides for peripheral vision), then the same solution works for eyefinity. Sit closer, or turn the FOV down :p
 
To explain the fisheye... it's actually correct. The reason you don't notice it in real life is because humans have about 120 degree FOV and the 'fisheye' would always be in your peripheral. Namely, you can never look directly at your peripheral because that's how peripheral is defined. So it's much the same for eyefinity except you can obviously look at the side monitors with no problem. That said, you're not really meant to focus on the side monitors for too long anyway.

A geometric explanation would be... no matter where you are on the screen, vertical lines must remain vertical while parallel lines must remain parallel (the easiest reference would be horizontal lines). There is no way you can 'correct' for it without A) reducing FOV, B) violating one of those rules (lines bending on the side monitors). A good example is this: http://img534.imageshack.us/img534/2142/baltimore.jpg

There is no 'fisheye', but obviously the lines are bent. The '3rd party' software that your friend mentioned is most likely the correction in SoftTH. To do such a correction is costly since it requires rendering an image much larger than what you actually see.
 
The fix for the fisheye effect (which is completely normal) is to look at the centre display and not directly at the side displays.

If it really continues to bother you then you can reduce the FoV, which is what is causing the fisheye in the first place.

It's really important to be sitting in the middle of your Eyefinity display and looking straight ahead. If you're at a friends house watching it from over their shoulder and looking directly at their side screens (which simulate their peripheral vision) then yes, the fisheye is going to look wierd. When you play and want to move your line of sight, don't move your head to look at your side screens, move your mouse to put what you're looking at in your crosshairs.
 
Unknown-One said:
There are a couple of things you have to understand about how game cameras work. The "distortion," as you call it, is 100% optically correct.

1. Game cameras use one-point-perspective, and place that point dead-center. Because of this, a given FOV can only be viewed properly when looking at the very center of your screen.
2. A given FOV can only be viewed properly when sitting a certain distance from your screen. This is dependent upon the physical size of your display.

I'm sure you've seen what happens when you turn the FOV up too high on a 4:3 monitor, everything goes fisheye. The solution is to sit closer, or turn the FOV down.

Keeping in mind that you should only ever be looking directly at the center screen because of the fixed one-point perspective (using the sides for peripheral vision), then the same solution works for eyefinity. Sit closer, or turn the FOV down :p
Click to expand...

Yeah, but with Eyefinity you set the screens up so they're all pointing toward you, opposed to having a single large flat display.

I didn't try playing with the FOV settings in the games, not sure if they all had FOV options. I calculated it out and where I was sitting given the size of the screens the FOV should have been set to about 100-110 degrees, which in racing games wasn't enough to see the both rear vision mirrors. EDIT: Actually if I'd sat a bit closer, the FOV quickly jumps to about 140 degrees because of the screens wrapping around.

The problem seems to be that the game assumes as you up the FOV, you are using a flat display and are sitting closer and closer to it, rather than extending your view around you.

I guess for Eyefinity to have the correct degree of "warp" to the image, you need to have your 3 screens arranged flat and sit however close you need to be to get the correct FOV... doesn't seem like a terribly attractive idea. Otherwise the game camera needs to some how assume you have wrap around displays and compensate for it. Though I need to try and lower the FOV settings to ~110 degrees and see if that helps.

I think my problem is I was really looking forward to Eyefinity blowing me away and wanted my own set up that I was a bit disappointed with it when I saw it in the flesh :p
 
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Tudz said:
I guess for Eyefinity to have the correct degree of "warp" to the image, you need to have your 3 screens arranged flat and sit however close you need to be to get the correct FOV... doesn't seem like a terribly attractive idea.
Click to expand...

How big are your friend's screens? I'm using 24" 16:9 ratio screens and they are practically in a straight line with a slight angle towards me. Maybe 15%. They are IPS panels so they don't need to be pointing directly at me, they have really great viewing angles on them.

It's pretty damn wide. I think about 66" on the diagonal and normal monitor's distance away from me. When I'm leaning over the keyboard whilst playing a game, there is very little in my peripheral view that isn't display. I would imagine with 27" screens, with only a very slight angle, you'd be filling up most of your peripheral view with the correct image.

If your friend's screens are smaller, or if they are at some 33% or more angle then that fisheye is going to just look wrong.
 
Widescreen Fixer is the app that adjusts FoV in several games.. You would be setting the FoV down to reduce the amount you can see, and thus how much of the fisheye shows up, but you probably won't like the claustrophobic result.
 
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