All about Field of View (FOV)

This guide covers the basics of Field of View in racing games, but focuses specifically on Assetto Corsa. This game/sim uses vertical FOV, but the principles are exactly the same as hFOV.

If you just want to get your FOV right but don't care about the technicalities, skip right to "How to determine FOV - Single Monitor Setup" if you have one monitor or skip to the next section for triple monitors, and ignore the rest.

Introduction

Why are you on this page? Why do you want to know about FOV? Most people just disregard the FOV slider/value, or they toy around with it until they can see the whole dash and side mirrors comfortably. Are these people right in doing so? Of course they are - if they want to play an arcadey racing game and don't care about having an accurate view of the (virtual) world - they are right indeed.

But let's get to business. Certainly, the FOV value is arguably the most important value you must modify if you wish to have a realistic sim racing experience. In the following passages, you will learn about FOV, how to set it correctly to fit your sim racing rig (even if it is a puny desktop with a single monitor and a wheel attached to it, like myself!), and finally know the things you need to get as close as possible to a real racing experience in your very home.

Addendum:
To fully enjoy life-size on-screen visuals, near-180 degree viewing image that covers your periphery, and a feeling of speed given the former, you must have a triple monitor setup or an Oculus Rift (or similar); this document will explain why that is the case in the next section. Nevertheless, in my opinion, you can play perfectly fine without peripheral view while having an accurate field of view. I improved my times significantly given that a correct FOV enables you to estimate the correct time to brake in order to hit the apex and not overshoot the curve; a higher than optimal FOV causes everything in the focus area to become really small and to look like it's slower than it actually is, causing you to overshoot corners. An excessively small FOV, on the other hand, causes your view to look like you are using binoculars while you drive, where you can see objects really far away but you can't see anything around you!

With that said, if you can get a triple monitor setup, by all means do so. Better yet, if you can get an Oculus Rift, get it! It is very much superior than a triple monitor setup where immersion is concerned, yet it costs a fraction of such a setup.

If you just want to modify your FOV and are not interested in the technicalities, skip to the "How to determine FOV" section that applies to your setup.

A Crash Course on FOV

First and foremost, lets clear up a misconception. When most people are talking about Field of View, they are actually talking about Angle of View (or AOV). Strictly speaking and by definition, FOV (or field of view), is the distance covered by a projection at a certain distance; in my case (when looking at my monitor) at a distance of 75 cm, my field of view is 34 cm (the height of my monitor) with an angle of view of 25 degrees. Yet, most (if not all) games refer to FOV in degrees, and as we just saw, the AOV is measured in degrees, not the FOV. Nevertheless, for uniformity's sake, we will refer to FOV in degrees, like most people and games do.

FOV, that mysterious setting you can alter in many (though not all) racing games and simulators, that configuration you always thought was an arcane and even archaic setting, is not a very complex concept to grasp. Indeed, FOV is the term used to describe the scope of observable world from a specific point of view. In layman's terms, it is the angle of the cone of vision of a specific viewer.

In the case of a computer racing game, the FOV numerical value that you can edit represents the amount of image "crammed" into the computer screen. Just picture this: If my monitor was a window, my FOV would be 25 degrees into that window. What we are trying to do is to make this image look as close as possible to what we would see if we were sitting in the car in real life, with this window floating in front of us. Indeed, the goal is to make the virtual FOV match the real life FOV of our eyes against the window (monitor). Of course, there's a fundamental problem with this, and it is that the further away you get from your screen, the smaller the FOV should be. Just stand in front of your bedroom window and start backtracking, notice how you can see less of the outside world? Same applies to the monitor, the closer you are, the more of the virtual world you can see through it. That's why you should try to keep the distance between your eyes and the monitor uniform, always.

Default FOV


This here is the default FOV on a Ferrari F40. Sure, you can see the entire dash and almost the left mirror, but everything looks really, really small - especially in the focus zone, where it looks as if the curve is really far away - hence you usually run off the road.

25 Degree FOV


This screenshot, on the other hand, shows the mathematically correct FOV for my setup after adjusting the camera using the arrows of the Onboard Settings in-game app. At this FOV and camera location, my Logitech G27 overlaps the virtual wheel nicely, though not perfectly since the F40's wheel is much larger in real life than my G27. Regardless, I feel like I am sitting in the F40, albeit with a blind on my peripheral vision. That's why the closest you are to the screen, the higher FOV you can achieve, and with a triple monitor setup as close as possible to you, you can achieve almost full horizontal view.

Once you set up your FOV correctly, remember to use the arrows to move the camera so your real wheel overlaps the virtual wheel; then, after you've done that to all your cars, you can and should make the virtual wheel invisible in the launcher settings.

iRacing - NASCAR Gen 6 Ford Fusion

This video exemplifies my theory perfectly. It is one of the single best examples of what you can achieve with a proper setup and field of view. This person has a triple monitor setup enclosing the racer's field of view, with the racing wheel right in front of the screen and the motor under and behind the center monitor. This gives amazing immersion, only defeated by projector or Oculus Rift (VR) solutions.

F1Driving

Do you want a professional example? Fine. Same concept - the company will not even release their specs but we know how to achieve them. Correct cockpit setup and FOV is all that is needed.
On this video you can see Fabio Onidi practicing on a professional racing rig. From the point of view of Fabio, the tyres and the track look just like the real deal, proportion wise. That is what we're trying to achieve. Notice that the former video is of a regular Joe like any of us, that has his setup as good as a professional.

If you want more insight on the topic, visit my sources at the end of this document. Of especial interest is the post by ZeosPantera in the NoGrip Racing Forums, where he was bashed for stating that a close to real experience can be indeed achieved with a good FOV and racing rig setup. Also of interest is the "Field of View Explained" article by Maximilian Schulz of the iRacing community.

Understanding the FOV formula

Caveat: Skip to "How to determine your specific FOV" if you don't care about the workings of angle of view.

The first time I saw the FOV formula, I thought to myself "how cool! Math is so useful and versatile, you can use it for everything! Except to get women. Actually, a fu**er with game could use math to get lai...... wait a minute now, how did this guy get the formula? And how do I know it is correct and it works?"

And so my research began. Turns out, it's not as complicated as I thought. I just had to refresh my trigonometry, as I've forgotten quite a bit of it being an English and Econ double major (since I use calculus in Econ).

Get ready, because this info is a collection of generic trig information mixed with the world of sim racing that you won't find elsewhere! Or maybe I just suck at using Google and I wasted my time figuring this stuff out on my own. Just joking, I really I wanted to learn all about FOV and how it works mathematically so learning by myself was the best option. Mind you, I researched this at 2:00 AM, while tired, so it took me some time to grasp it. Or I could be completely wrong, though I'm quite sure of the opposite. But I digress!

Basic Trig:

Function	Description
Sine	SIN ϴ or H / 2 or Opposite / hypotenuse
Cosine	COS ϴ or D or Adjacent / hypotenuse
Tangent	SIN ϴ / COS ϴ or (H / 2) / D or Opposite / adjacent or hypotenuse slope
Arctangent	TAN^(-1) or ARCTAN or Inverse of tangent or 1/2 of FOV angle

ϴ = Theta
D = COS, Distance from monitor to eyes, personal example 75cm
H = SIN * 2, Monitor height, Personal example 34cm
H / 2 = SIN, half of the monitor height, opposite line to our right triangle

With those definitions in place, we can determine the FOV using trigonometrics. If we make an imaginary triangle that forms from the lines that run between our eyes and the vertical line that runs the height of the monitor, we know that the FOV is the angle that forms between these two lines (denoted by the blue lines on the diagram). For the trigonometric functions to work, there needs to be a relationship between the lengths of the lines in the triangle and the angles that form this triangle; therefore, we take the (GREEN) line from our eyes directly to the center of the monitor, and the (BLUE) line from our eyes to the top edge of the monitor, and we form an imaginary right triangle.


Now, we need to take all the data we have in order to obtain the data we don't have (FOV angle). We know that the green line is D, the orange line is H, and the blue line's slope is TAN ϴ.

By definition, the tangent is SIN ϴ / COS ϴ, which in layman's terms is the opposite / adjacent of ϴ, so

TAN ϴ = (H / 2) / D
TAN ϴ = 0.5 * H / D 

For us that makes
TAN ϴ = 0.5 * 34 / 75
TAN ϴ = 0.226

Notice we need half of H to make a right triangle, hence we multiply H * 0.5.

We have the slope of the hypotenuse. To find the angle of ϴ, we need to use the inverse of the tangent, ARCTAN.

ϴ = ARCTAN (TAN ϴ)
ϴ = ARCTAN (0.5 * H / D)

ϴ = ARCTAN (0.226)
ϴ = 12.77

If you see the second graph, you will notice ϴ is the angle of the leftmost triangle. Since they are right triangles, both left and right triangles are symmetric and therefore have the same angle ϴ. Therefore,

FOV = 2 * ϴ

FOV = 2 * 12.77
FOV = 25.54 degrees

In summary, all we did to obtain the FOV was to make a right triangle out of our field of view cone, then we used the adjacent and opposite sides to obtain the tangent (hypotenuse slope), then we used the ARCTAN function to get the angle of our right triangle, and we finally multiplied it times 2 to get the angle of our cone (FOV).

The final usable formula looks something like this:

FOV = 2 * ϴ  
FOV = 2 * ARCTAN (0.5 * H / D)

How to determine FOV - Single Monitor Setup

After all that information, or if you skipped it entirely, you will want to know how to actually set your FOV perfectly for your specific setup. There are two simple ways to achieve your mathematically correct field of view. Method 1 is achieved through the use of a formula, while Method 2 is attained through the use of an online FOV calculator (which is essentially a frontend for an algorithmic formula).

• Method 1:

  Use Project Immersion's FOV calculator[www.projectimmersion.com]. I tried the formula in method 2 as well as the FOV calculator in method 1 and both returned the same value.
  
  As of Feb 2016, I cannot seem to be able to plug in my exact vertical height in Project Immersion's FOV calculator. Setting the slider to 27" (my monitor size) and 75 cm distance, I get 25.37 degrees, which is different but close enough so as to not matter. User SuperBobKing mentioned in Jul 2015 that "diagonal size for monitors is rarely accurate, so it is better to measure". My point is, you will probably get the correct number for your setup but YMMV.
  
  

• Method 2:

  For this method, you will need the Height of your monitor screen, the Distance from your eyes to the monitor's screen, and the formula to obtain the angle of view. You can either measure your exact monitor manually, or you can refer to the table in this page[en.wikipedia.org] to get the value. Look for your monitor in standard diagonal inches (or in centimeters), and go to the table corresponding to your monitor's aspect ratio. In my case, my 27" monitor uses table 16:9, where my screen height is 34 centimeters.
  
  

  FOV = 2 * (ARCTAN (H / (D * 2)))

  
  H = Monitor height in your preferred unit of measurement.
  D = Distance from your eyes when sitting in front of your wheel to the monitor screen, in the same units as the height.
  arctan = the inverse function of the tangent. You can use tan^(-1) in your scientific calculator, or you can use the arctan calculator at this location:
  Arctan calculator[www.rapidtables.com]
  
  EXAMPLE:
  My screen is a 27" gaming monitor which sits 75cm away from my eyes and has a height of 34cm (NOT measured from the top corner to the bottom corner, but rather in a straight vertical line with an undefined slope). Bezel not included in measurement!
  
  So, we plug our data in:
  
  FOV = 2 * (ARCTAN (H / (D * 2)))
  FOV = 2 * (arctan (34 / (75 * 2)))
  FOV = 2 * (arctan (34 / (150))
  FOV = 2 * (arctan (0.226))
  FOV = 2 * (12.77)
  FOV = 25.54 degrees

I highly recommend you use both method 1 and 2 in order to confirm your FOV value is correct.

How to determine FOV - Triple Monitor Setup

So you have three monitors, you lucky fuark. Begin by packing your monitors in bubble wrap, stuffing them into cardboard boxes, and shipping them to me. Ok, stop looking at me like that, I'm joking.

Launcher Options

To set your correct FOV, you need to let the game know you have three monitors. You do this by going to the Options menu, and on the Display tab, select your appropriate Resolution, Rendering Mode, and whether you will be using Fullscreen Rendering.

Resolution is rather simple, if you have three identical monitors, or at least if you have monitors with identical native resolutions. If you have three 1080p monitors, you will likely see the option to select the resolution 5760 x 1080, because 1920 (width resolution) x 3 = 5760 pixels. This is usually the case in other games, so don't quote me on this as I can't verify.

The Rendering Mode is obvious; choose "Triple Screen" if you have three monitors.

Now, Full-screen Rendering, the elephant in the room. I can't verify either way, but some people with different resolution monitors have reported they get better results without full-screen rendering. If you have three identical monitors I suggest you use Fullscreen Rendering, unless you have a reason not to. Once you have these settings, go pick a car, a track, and launch the game.

In-Game Settings

Caveat: People have reported the game is not "plug and play", meaning that getting your exact measurements and plugging them in won't guarantee the game will look perfect. I recommend you plug your exact numbers, and then tweak the sliders a bit if you're not content with what you see. Plugging your numbers in correctly will get you very close anyway, if not perfecty.

When you launch the game, you will see your car in first or third person view. Make sure the camera is in the cockpit by pressing the F1 button until you are there. Next, scroll your mouse over to the right of the screen, and the apps dock will appear. Now look for the Triple Screen app - you WILL have it if you selected Triple Screen rendering in the launcher. Click on it and a large window with a bunch of settings in it will appear.

Default Settings
What you will first see when you open the app is a top-down perspective of the current settings. In other words, how the game interprets your physical, real life racing rig. Additionally, the four settings you will see are ROTATION_SPINNER, DISTANCE_SPINNER, SPINNER_SCREEN_WIDTH, and MARGIN_SPINNER, all of which will be explained further down below.

Rotation Spinner
The rotation spinner indicates to the game how much angle exists between your middle monitor (marked green) and the two lateral monitors (marked red). In this case, I set the monitors to 45 degrees.

Distance Spinner
The distance spinner tells the game how much distance exists between your eyes and the middle monitor's screen. Grab a tape measure and get the distance in millimeters (hell yeah metric system). If you don't have a metric tape, measure in inches and use Google to convert the units to centimeters (eg. type "40 in to cm" in google, without quotation marks). I recommend you get your monitors as close as you possibly can without getting ill; as a rule of thumb, if you can get your steering wheel to be a few centimeters away from the screen, with the motor under the monitor, do it. The first video in the Crash Course section is the best you can get.
In this case, I set the distance from the default 1000 cm to 500 cm, YMMV.

Spinner Screen Width
The spinner screen width tells the game the width of EACH INDIVIDUAL MONITOR not including the bezel and measuring with the tape/ruler STRAIGHT, NOT DIAGONAL. In other words, if the screen was a stadium field, what's the distance from each touchdown/goal/etc?
In this case, I set the width to 1430mm.

Margin Spinner
The margin spinner tells the game how thick the Bezels of your screen are. Measure in millimeters and plug the number in. This slider can curiously go to the negative numbers, which I have no idea why is the case. Maybe it's a bug, or someone can make use of it somehow, but don't ask me.

Once you set all of these right, your setup should look pretty close to real. After you set your FOV this way, make sure to go to the Onboard Settings app and move the camera around so that your real wheel overlaps the virtual wheel, and you are done! This camera setting is independent for each car, so you will have to configure each car and press the Save button for each car.

Notice: The settings I put here are fictional, I do not have a triple monitor setup nor a 60" TV with a 1430mm wide screen. That's just silly.

How to determine FOV - Oculus Rift

Select "Oculus Rift" under the rendering mode submenu. The FOV should work out of the box as this game supports the Oculus Rift natively. DK2 support is not yet implemented.

How to get the most realistic experience

So you want to feel like Michael Schumacher and Mika Häkkinen, huh? There's a few things you can consider in order to get there without having an eight figure bank account or being a child racing prodigy working for a racing team. This section is just a little bonus on things I would recommend you obtain in order to get an an extra bar on realism for each of the following that you accomplish.

• Get a 27" or larger monitor.
  
• Get three 27" or larger monitors. Highly recommended.
  
• Get a racing cockpit, make sure it doesn't have a bar between your legs so you can use the clutch or brake with the left foot without issues.
  
• Get a projection setup
  
• Add a curved board to your short throw projector setup
  
• Get an Oculus Rift
  
• Get a 5.1 or 7.1 surround sound system
  
• Get a high quality stereo Headset for when you don't want to bother everyone in your neighborhood. From what I've read, 5.1 surround headsets are a gimmick, so get something like an Audio-technica, Sennheiser, etc.
  
• Get a SimVibe rig or similar, to "feel" the ride
  
• Get a fan and feel the wind as if you were really in the open
  
• Get your girlfriend a paddock girl attire so you feel like a real racer
  
• If previous item does not apply, get girlfriend

*Last three items are sarcasm, for those with broken humor detectors. They do make the experience more enjoyable though. Or less, depending on the girlfriend.

Like and favorite if you found this guide useful! Enjoy.

Works Cited

"Degree-Radian Conversion" by Inductiveload - Own work. Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Degree-Radian_Conversion.svg#mediaviewer/File:Degree-Radian_Conversion.svg

"Field of View." PanoTools.org Wiki. Panorama Tools, n.d. Web. 3 Aug. 2014. http://wiki.panotools.org/Field_of_View

"Inverse trig functions: arctan." Khan Academy. N.p., n.d. Web. 18 July 2014. https://www.khanacademy.org/math/trigonometry/unit-circle-trig-func/inverse_trig_functions/v/inverse-trig-functions-arctan

Schulz, Maximilian. "Field of View Explained." silverball-magic. Version 1.1. iRacing.com, 30 Apr. 2011. Web. 18 July 2014. http://www.silverball-magic.com/my-stuff/Field_of_View_Explained.pdf

ZeosPantera. "Setting up your FOV - Tutorial." NoGripRacing Forums. Version 1.0. N.p., 25 July 2010. Web. 18 July 2014. http://www.nogripracing.com/forum/showthread.php?p=1160743

Pix, Mr, and Zeos Pantera. "FOV Calculator (WIP)." Project Immersion. Version 0.4 beta. N.p., n.d. Web. 15 Aug. 2014. <http://www.projectimmersion.com/fov/index.php?m=1>.

Changelog

v2.1.8 - 02/09/2016 - Fixed changelog. Updated section title. Updated Single Monitor section. Added and clarified theory section. Added labels to B&W graph, added ovalman
v2.0.1 - 02/15/2015 - Fixed works cited links which Valve was nice enough to break. Thanks MrPix
v2.0 - 08/25/2014 - Major change. Changed entire guide from horizontal FOV to vertical FOV
v1.2 - 08/14/2014 - Added section on how to setup FOV in Oculus Rift
v1.1.2 - 08/02/2014 - Added section on how to setup FOV in Triple Monitor setups, edited a few other sections
v1.0 - 07/18/2014 - Guide published

[sputnik]

this is some schizoposting shit but I'm leaving good rating anyway

[cuWILLISnt]

man most the people complaining cant do maths... ive spent like 10 hours trying to figure this out xD i am glad i can do math. this was really useful.

[Sen]

people really are the most embarrassing people on earth

[Bluwaffle]

people with pfps really are the most embarrassing people on earth

[Sen]

people with anime pfps really are the most embarrassing people on earth

[irchadr]

simracers really are the most embarrassing people on earth

[Lyro the Synth]

FOV Calculator unfortunately no longer shows up, it's now an advertisement banner for FANATEC gear.

[lx]

i wonder if this includes a properly distanced focal point

[Unicorn]

you wrote more about how to get a good fov in a video game than my college essay

[Antonio Tavares]

FEELING... some guys won't learn no matter what. FEELING is having a simulator correctly configured to SIMULATE the reality it is intended to simulate. Incorrect settings lead to incorrect FEELING, incorrect evaluation of speed and distances, thus to arcade driving,