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# trying to get a more "true-eye" projection going

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7 replies to this topic

### #1Norman Barrows  Members

Posted 27 March 2014 - 12:30 PM

from a post in another thread:

"Paleolithic setting - thus no lens effects.   I've been thinking about playing around with the FOV some more, to try to get a more "true-eye"  projection going.  humans have a stereoscopic field of view of about 90 degrees horizontal, but a peripheral field of view of 120 to 150 degrees horizontal. vertical stereo and peripheral FOVs are both about 90 degrees. the aspect ratio is about 3:1, depending on the shape of the face around the eye.  anyone know if directx can do something like this? perhaps with letter boxing to get the desired aspect ratio, once the FOVs are correct?"

how might something like this be achieved?

in the past i've played with FOV's ranging from 30 to 120 or 150 degrees.   wide fov's produce a "rolling" or "wrap over" effect at screen edges. its noticeable in skyrim, where people are wider at the left and right sides of the screen than when directly in front of the camera.

another thing i've noticed sometimes is a fisheye lens effect, apparently caused by the fact that a simple divide by z foreshortenting actually reduces the 3d distance of a point to the camera if its lying off-center.

it seems to me that a rotation towards the center line, as opposed to a translation along x or z in camera space (IE divide by z) would be the more correct way to do it.  i do realize this probably means some sort of custom projection transform routine to replace the usual projection matrix part of the pipeline.

Norm Barrows

Rockland Software Productions

"Building PC games since 1989"

rocklandsoftware.net

PLAY CAVEMAN NOW!

http://rocklandsoftware.net/beta.php

### #2Bacterius  Members

Posted 27 March 2014 - 04:40 PM

Have you tried a spherical projection, not fisheye but a smaller section of the sphere? I don't know if DirectX lets you do that but it seems to me it would approximate human vision better, worth a shot IMHO.

“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”

### #3/ fir   Members

Posted 27 March 2014 - 05:39 PM

I think to simulate wider apsect of view there should be a three monitors (screens), two settet at some degree like -30 +30 degrees making a side projection

__

/     \

human

Is tt possible to make a game on three monitors today? Imo that should give a good effect ,

### #4Hodgman  Moderators

Posted 27 March 2014 - 06:19 PM

The issue with wide FOV's, and why they look ridiculous, is because your monitor only takes up something like 20º of your actual field-of-view. If you set up three monitors as suggested above, so the screens more fully fill up your field of view, then a 110º in-game FOV won't look so ridiculous any more

Some modern GPUs support this without any special coding from the game - the user can just choose to configure their 3 screens to act like a single large screen, and then the game just sees that the user has a 5760x1080 resolution monitor with a 16/3 aspect ratio. If you want to support this on other GPUs, you can create three windows for your game, and split your rendering results into three sections, blitting different sub-sections onto the 3 windows.

To try and make this work on a single screen for gameplay purposes (to give people perhipheral vision) is a bit of a challenge... Maybe you could do a wide-FOV rendering, but then split the results into a few sections and rescale them to combat the distortion, e.g.

   original          rescaled
_____________     _____________
|_A_|_B_|_C_|  -> |A|___B___|C|

Edited by Hodgman, 27 March 2014 - 06:22 PM.

### #5/ fir   Members

Posted 28 March 2014 - 07:13 AM

The issue with wide FOV's, and why they look ridiculous, is because your monitor only takes up something like 20º of your actual field-of-view. If you set up three monitors as suggested above, so the screens more fully fill up your field of view, then a 110º in-game FOV won't look so ridiculous any more

Some modern GPUs support this without any special coding from the game - the user can just choose to configure their 3 screens to act like a single large screen, and then the game just sees that the user has a 5760x1080 resolution monitor with a 16/3 aspect ratio. If you want to support this on other GPUs, you can create three windows for your game, and split your rendering results into three sections, blitting different sub-sections onto the 3 windows.

To try and make this work on a single screen for gameplay purposes (to give people perhipheral vision) is a bit of a challenge... Maybe you could do a wide-FOV rendering, but then split the results into a few sections and rescale them to combat the distortion, e.g.

   original          rescaled
_____________     _____________
|_A_|_B_|_C_|  -> |A|___B___|C|

do you know maybe, or some other person, If one would like to do it in wery todays coding environment like win32 gdi or sdl or opengl (game on three screens) How it is done - You just made a three fullscren windows instead of one and call DrawFrame(Window* w) for each of the window? (I got no two monitors so i cannot check it up if this differs comparing to just

running the game to three winapi windows in at one desktop)

Though I suppose probably not so it is really very easy (though ofc probably will work near 3 times slower) or less? or more?

### #6Norman Barrows  Members

Posted 28 March 2014 - 02:35 PM

Have you tried a spherical projection, not fisheye but a smaller section of the sphere? I don't know if DirectX lets you do that but it seems to me it would approximate human vision better, worth a shot IMHO.

don't know if directx can do that.

spherical might address the divide by z issue.

Norm Barrows

Rockland Software Productions

"Building PC games since 1989"

rocklandsoftware.net

PLAY CAVEMAN NOW!

http://rocklandsoftware.net/beta.php

### #7Norman Barrows  Members

Posted 28 March 2014 - 02:45 PM

The issue with wide FOV's, and why they look ridiculous, is because your monitor only takes up something like 20º of your actual field-of-view. If you set up three monitors as suggested above, so the screens more fully fill up your field of view, then a 110º in-game FOV won't look so ridiculous any more

well, i'm thinking about things like:

looking at lines going off 45 degrees left and right, the lines should appear straight and perpendicular to each other.

the "rolling at the edges" effect of wide fov's.

the "fisheye" effect.

what causes these artifacts?

how does varying the fov affects the scene?

i tested fov's of 30 degrees, its sort of like zooming in, but everything is much "flatter" with less curvature distortion.

much of this has to do with how the scene behaves as you rotate the camera. objects get wider or narrower near the center or edge, perpendicular lines aren't perpendicular,  straight lines aren't straight....   the real world doesn't look like this...     or are my eyes just weird ? <g>.

i think i need to play around with it some more.  hook up your fov to some inc and dec hotkeys sometime, its really cool!  you can actually turn it into tunnel vision, then inside out!

Norm Barrows

Rockland Software Productions

"Building PC games since 1989"

rocklandsoftware.net

PLAY CAVEMAN NOW!

http://rocklandsoftware.net/beta.php

### #8Norman Barrows  Members

Posted 28 March 2014 - 02:56 PM

To try and make this work on a single screen for gameplay purposes (to give people perhipheral vision) is a bit of a challenge... Maybe you could do a wide-FOV rendering, but then split the results into a few sections and rescale them to combat the distortion, e.g.

i'm thinking narrower fov's, and rotate the camera for the peripheral views.

but there you're basically talking about rendering 3 scenes....

as i said, there seems to be a direct relation between bigger FOV and more distortions of a "spherical" nature (for lack of a better term).

aspect ratio also comes into play. i messed around with this before with Caveman 1.x back in 2000-2003, when widescreen monitors had yet to become common. when playing "choose a FOV" this time, i found it much easier, since i'm targeting a 16:9 aspect ratio, as opposed to 4:3.

more stuff to experiment with...

Norm Barrows

Rockland Software Productions

"Building PC games since 1989"

rocklandsoftware.net

PLAY CAVEMAN NOW!

http://rocklandsoftware.net/beta.php

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