Well, I have a question about the graphics of the Doom 3 BFG Edition, because I have noticed something that does not affect the gameplay much, yet, on the deeper look, it confuses me a bit, so I wonder if anybody has noticed this “problem”, as I have searched in the internet for it, but found nothing, even after having done several searches.

Have you ever noticed that, even having set all of the graphical settings to the absolute maximum, with no exceptions, that the graphics look pretty sharper if they appear on the sides of your computer screen, than if you center your view on them? If you don’t know what I mean, then try the following and I hope that my English is well enough to actually make it understandable:

Start a new game of Doom 3 BFG Edition and move forward until you are in the departure lounge of Mars City, right after the security checkpoint. Then get close to the information terminal, where the welcome video of the UAC is being played. Then, turn to the right and center your look straight to the other information terminal, from which you can download an email, as soon as you have received your PDA from the receptionist. Now, if you look closely, you see that you can barely read the letters on that screen, if you are standing a few meters away from it and keep the screen in the center of your sight. But now turn your look to the left or to the right, until the screen of the information terminal is at one of the sides of your actual computer monitor. Now, suddenly, you can read the text on the information terminal clearly, even as you did not went one step closer to the information terminal itself.

This strange effect is also very easy to be seen when you make your way through Mars City, until you reach the infirmary. Jump onto the chairs, from which you can take a look at the wounded marine, lying on the table of the infirmary. Center your look and his ripped off face is kind of blurry, but turn your character as much until the face of the wounded marine is on the left or right side of your actual computer monitor and his ripped off face is now very sharp to see and therefore presents itself in a much better visual quality, than if you would keep it in the center of your sight.

I hope you understand what I mean, as I have tried to make in-game screenshots, but they are all TGA and much bigger than the actual size of files that is allowed on GOG to be uploaded. Again, all of my graphical options are set to the max, including the resolution, anti-aliasing and even the field of view, although changes in the setting of the FOV seem to not make any difference, as I have read that the BFG edition has a narrower field of view than the original Doom 3 anyway. And if this should be helpful as information: I do not play in the 3D mode, that the BFG Edition offers. The introduced motion blur effect of the BFG Edition is also shut down, as I never was a friend of that either.

Having played the original Doom 3 just one time, which was even 8 years ago, I have no idea if this strange graphical effect, as I call it, was already existing in the original. I just would like to know if anyone of you has ever found this strange effect too or if someone maybe even has a explanation as to why this effect exists. It does not disturb the actual gameplay in any way, but I wish that the entire screen would show me everything as sharp as it appears on the sides of my screen. And no, this has nothing to do with my monitor, as this effect occurs only in the Doom 3 BFG Edition but in no other game or program that I use on my computer. Therefore, it must be something BFG only, that I personally cannot explain, yet as I have found nothing about this effect in the internet, it seems as if I would be the only one who ever noticed this, which I personally do not believe so.

EDIT: I was able to create screenshots now and was able to convert them as well. Please take a look at them, to see what I mean. I think especially on the pictures 4 and 5 (GOG forbid me to add a 6th picture) it is very good to see how the wounded marine is blurry when I have my look centered on him and how he is becoming visibly sharp, as soon as he appears on one of the sides of my screen (I got the same result when he is on the right side of my screen). It also appears on the screenshots as when I turn my character that the objects on the sides of my screen are suddenly closer than they were when they are in the center of my screen. I promise you, I did not walked another step, I just turned my character around. Same with the letters on the information terminal in the departure lounge. Blurry in the center, but more better to see when they are on the sides of my screen. You'll see this especially good when you focus on the download button of the terminal. Please be reminded that I had to reduce the quality of the original screenshots, so that I was able to upload them onto this forum, so these edited screenshots are not what my game looks originally, as all of my graphical settings are set to the maximum.

Just convert those tgas to jpeg and reduce quality a bit (500kB/image), or upload them elsewhere (e.g. imgur).

Hello, thanks for your helpful reply! I was able to make jpegs out of the tga screenshots now and reduced their quality a bit, to apply with the GOG limitations, please see the edited version of my post. :)

I don't know about that blurriness, but the reason why you see more detail when you look at objects on the side of the screen is simply the way FOV is implemented in these games; it stretches the view at the edge while things at the center are made smaller.

Given twice as many pixels, you get twice as much detail..

Aaah, I see now! So it is truly something ingame, that cannot be changed. Now I just wonder if the original Doom 3 had this effect as well, since the BFG Edition has a narrower FOV and the original Doom 3 had also a zooming function, just as Quake 3 has as well. Would be interesting to find out, if GOG ever should be able to release the original non-BFG Doom 3.

Anyway, thank you very much for your explanation and the picture as well! :)

Virtually every commercial 3D game has this effect, as they simply project the scene on a flat plane using a perspective divide (and sample texture according to 1/z). This is how GPUs work. And it inherently distorts the scene the way you observe. The lower the FOV, the less distortion you get. At higher FOVs (near the maximum of 180 degrees), the distortion is quite extreme, everything straight in front looks just absurdly small while things near the edge stretch far out toward the center.

Here's an example (the left screenshot):

https://raw.githubusercontent.com/shaunlebron/blinky/master/readme-img/old-and-new.jpg

If you want to see why it works the way it works, check this out: http://shaunlebron.github.io/visualizing-projections/

See under "Standard projection", there are circles you can drag, and a flat plane between them and the camera representing the image plane. Drag one circle so that it is straight in front of the camera. Grab another circle and drag it directly left or right of the first circle. The further you go, the longer its projection becomes on the image plane, even though it is getting further away from the camera!

If games projected on a spherical or parabolic surface instead of a flat plane, you could go well over 180 degrees and without such absurd distortion. Also, even at smaller fovs, you can get a (subjectively) more pleasant form of distortion that roughly keeps everything the same size (or shrinks things at the edges instead of at the center, like a fish eye lens).

Here's a video demonstrating the effect of increasing fov with standard flat plane projection. Then it goes on to break the 180 degree barrier with a better projection: https://www.youtube.com/watch?v=jQOJ3yCK8pI

I think the implementation here works by performing six 90 degree standard projections (for a complete 360 degree cube, see the end) and then mapping pixels from that cube to the locations they would be in a spherical projection.

EDIT: A loosely related effect is how many old (and maybe still some newer?) games implement fog that is a function of view space Z rather than the rendered surface's actual distance from camera. This means that you can see further away in the fog if you look at it "sideways". In multiplayer games you could cheat by having as high fov as the game allows, then looking sideways into the fog to spot enemies before they see you. With good mouse hand, you can even take aim and snipe them semi-blind.

Clarry, you are truly awesome! As I am just your average Joe when it comes to computers and video games, I was able to learn a lot from you and from the useful links you gave! And I think I should have just tested it myself, as I just took another look at Doom 3 and set the FOV from 100 to 80, which was the lowest option the game offered to me. Now, the FOV is indeed smaller than on 100 and I don't know why I haven't recognized a difference before, yet now everything in the center of my screen is just as sharp as on the edges! Yet, I have set it back to 100 for playing, as in Doom 3 you never know from where something might suddenly jump at you, so a maximized FOV might be vital, even as the edges of your screen will be sharper than its center. :)

To be sure that it is not just a Doom 3 only thing, as I still was wondering, I have taken a look at another favourite shooter of mine (Unreal Tournament 2004) and although it is not as "extreme" as in the Doom 3 BFG Edition, it also exists there (see the two attached screenshots if you like).

This is truly a very interesting discovery for me, even as I have played video games for almost my entire life and maybe should have known this already for many years. I guess, that Doom 3 was just the first game where I was able to truly see it clearly. Therefore, Clarry, thank you so much again for your awesome help and the wonderful and long explanation, as well as for the links! This is what I call a good help from the online community! :)