# FPS games: don't they have unrealistic one-eyed view? What are the causes?

I have played many fps games, and noticed that the camera perspective is similar to the 'one eyed view' of the surroundings. It does not feel like bilinear. :/

Is it because of the single flat view of the screen? Or is it the problem that can be fixed by some research?

PS: If you want, try to roam around with only one eye open.

• Is this not related to FOV?
– user15805
Jan 12 '13 at 15:07
• I thought that all FPS characters were cyclopes to start with. Unless the technology behind it uses 3D rendering in the real sense (stereoscopic view), you will just have to settle down for fancy post processing effects, improved shadows, fluids, gases, physics as that's what most people interested in FPS criticize or appraise most often in respect to this genre. Via post processing effects you get depth of field, radial blur, etc. that give the illusion of an observer's limited lens capabilities.. Jan 12 '13 at 15:45
• @teodron agreed, and as far as I know there does not exist such a game which uses actual stereoscopic 3D. the technique has been used in a few movies (Avatar for example), but I think it's infeasible in real time because it implies that you're going to render twice with two camera positions and then superimpose the images, doubling the amount of GPU time per frame. I think the way NVIDIA 3D Vision works it uses clever algorithms to turn a 2d render into stereoscopic 3d by analyzing the shading, which doesn't always work so great. Jan 12 '13 at 16:10
• "as far as I know there does not exist such a game which uses actual stereoscopic 3D." -> There are plenty, using a bunch of different techniques. I'm not sure stereoscopic 3D is what the OP is asking about though. Or is it? Jan 12 '13 at 21:27
• 3D Vision does render the scene twice - once for each eye - developer.nvidia.com/3d-vision-and-surround-technology
Jan 12 '13 at 21:41

I'll state the obvious - FPS games are doing the best they can within the limitations of a single 2D display device.

The interesting part - this might change soon thanks to the Oculus Rift project - a VR headset for games. I've seen info that DOOM 3 is fully supported (due to Carmack's involvement) and that Hawken has promised support. There is also work on external engine integration (Unity and Unreal were mentioned here).

Note the games on Oculus must support full stereoscopic 3D, since the headset has a separate display for each eye.

• I don't think the asker is really asking about stereoscopic 3D (since it's pretty obvious why that's not widespread) but rather about the field of view which is about the same as when you close 1 eye. Jan 17 '13 at 21:31

It's hard to tell exactly what's being asked here but I'll try to give the best answer I can. There are a few misconceptions going around in comments and answers so I'll try to clarify all this, to the best of my knowledge.

[I] noticed that the camera perspective is similar to the 'one eyed view' of the surroundings.

Indeed, the default (horizontal) field of view of first-person shooters (e.g. 75° in HL2) is notably smaller than the 'natural' FOV (around 95°). It might be close to a single eye FOV, but to me this is more or less a coincidence.

Is it because of the single flat view of the screen?

Not really.

This is simply a side effect of the display size. The FOV is reduced to compensate the fact that a regular screen doesn't cover your entire vision (you can see your environment around the screen, unless you stick your nose on the flat panel). Note than some gamers like to change this default FOV to something bigger for a better view of their virtual surroundings. So there is no single magic value used in FPS games: this is a matter of preferences and habits.

Stereoscopic 3D displays are quite common nowadays, and plenty of games support them, thus offering a proper 'two eyed view'. The default FOV is not changed in those cases: the fact that both of your eyes receive a different image doesn't change the relative size of the display compared to your vision.

Or is it the problem that can be fixed by some research?

I wouldn't call this a problem.

The 'fix' already exists, lots of game allow you to change the FOV on-the-fly, for instance try typing this in HL2's console:

sv_cheats 1;fov 95


This will seem to distort the perspective on a regular screen. To keep a natural-looking perspective with a high FOV, you simply have to use a display that covers your entire vision (stereoscopic or not). There are plenty of solutions:

• Add more screens, for instance through AMD EyeFinity. Games supporting this technology will enlarge the FOV to fit the new display size.
• Use a VR headset (expensive), or wait for the the much hyped Occulus Rift (or even customize an old Virtual Boy if you want to go retro).
• Another fancy upcoming technology that could benefit from larger FOVs is Microsoft's IllumiRoom - or, why not, a plain old overhead projector.
• Heck, if you've got plenty of money or a VR research department in your neighborhood, you could even go for a full-fledged CAVE.
• Microsofts illumiroom is a possible solution for the future too m.youtube.com/#/… Jan 18 '13 at 16:51
• @sednihp Added! Jan 18 '13 at 17:11

IMO the main reason for the usually limited field of view is preventing things like motion sickness and keeping aspect ratios sane (i.e. not looking awkward).

Most players will most likely sit around 30-50 cm in front of their screen, probably a bit more for console games. If you consider the screen to be a "window" you're looking through and its size, you'd be able to have a field of view of around 60-90 °, which is the usual setting used in these games as well.

Due to this you get a "realistic" view even while moving. If this doesn't really fit, the player might encounter things like motion sickness, or he'd just see the scene as through a fisheye (which usually isn't desired either).

Most games allow you to adjust the field of view to your liking within reason, and many seems to set it rather narrow as default - likely because it will perform better and I'd guess cause less issues with nausea that way?

It's not like you can actually recreate the feeling of roaming around with two eyes on a flat display without additional tools like shutter glasses and wider, closer placed displays or HMDs.

As Liosan said, only in the future we will change that (Oculus Rift is also coming to the steam box). But i think is a even more distant future. Oculos Rift just puts your head as the control of the camera (i think), so it will still be a flat image.

• Nope, that's wrong, the Rift has stereo 3D. And I don't see how stereo 3D is the future, it already exists today. Jan 18 '13 at 11:12