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TUTORIAL: FOV, Triple Screens & Immersion

Discussion in 'Automobilista - Links & Resources' started by GTSpeedster, Jul 17, 2018.

  1. GTSpeedster

    GTSpeedster FOV Geek

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    I began writing this tutorial a few years back on other forums and have been tweaking it on occasion and will continue to do so as the technology moves forward. The bulk of it is mostly aimed to the titles with proper triple screen support such as rFactor, rFactor 2, Game Stock Car, Automobilista, Assetto Corsa and iRacing; but it is still useful and relevant to all titles.

    A proper and mathematically correct setup is the Holy Grail of simulation as it allows for the 1:1 correlation between the real world and what can be reproduced and then experienced through the various platforms.

    And as an arduous and lengthy process of research and trial and error that this search naturally imposes I'll here then try to expedite it by paving a little less tenuous journey with this single thread.



    INTRODUCTION

    A single screen ordinarily does not allow for a proper 1:1 mathematical field of view to be implemented.

    That is because on a single screen you'd have to go for a very large sized panel of about +55" or so or to set up a projector screen; although neither still won't be covering your peripheral view, not matter how good they are.

    No matter how many or what size of screens you use as a rule of thumb you must always try to get as close as possible to the screen as to make its image relatively larger in relation to you, otherwise you're likely stuck having to find some middle-ground between your mathematical field of view and the other one that offers you with an enough and more comfortable view of the sides of your vehicle.

    If you're on a single screen you'll almost certainly have to reach a certain compromised, but the closer you are to your screen (and the larger they are) the smallest the compromised for your true FOV.

    Which leads us to what I repute as the best solution for the FOV: the triple screens. Be it monitors, TVs or projectors each will have its application depending on budget, room characteristics and designated applications. And no, I'll not be talking VR (Virtual Reality) at this point in time as I still don't regard any of the available sets as a fully developed solution that truly surpasses proper triple screens and without huge drawbacks. So please do not cry yourself dry.

    Therefore whenever any kind of triple screens are employed, for any kind of simulation, only a mathematically correct "RIG" with a proper 1:1 field of view should be acceptable, otherwise it nullifies all the labor, time and money invested on it.



    1. FIELD OF VIEW (FOV)

    For starters I DO NOT RECOMMEND the often mentioned "Project Immersion" website calculator. Mostly because in my view one should not rely on third party when better results can be achieve by doing it oneself. Additionally I don't know its author and I do admire his good intentions and efforts on providing it; it is practical and has lots of merits, particular if you're casual about your sim racing for its implementation of the maths is more generic with instances it won't get you completely covered with an absolut exact result.

    With that out of the way, the first rule of sim racing is: you do not talk about FOV as it being a matter of taste. The second rule of sim racing is: you do not talk it about it being a matter of opinion. Third rule: you do not say it's about personal preference.

    There is no subjectiveness regarding FOV. None! To state otherwise is wrong and, frankly, moronic.

    A mathematically correct FOV does never feel off as it does represent exactly what the real world feels and how it looks like. Therefore if your screen real estate and setup configuration allow for it you'll want to use only a proper FOV. Trust me on this!

    The FOV has many more important implications than people realize, as it directly affects the way depth and height are displayed and perceived. If the FOV is too high then the straights will look way longer than they are, turns will look less sharp and heights will look shallower. An incorrect field of view provides the so called "greater sense of speed" only because distances that appear longer are traversed in the same amount of time, thus defeating any purpose of simulation itself.

    The vertical FOV is calculated by taking half the height of the image (counting out the bezels and the rest of the frame of the device; and only measuring the actual display panel) and dividing it by the viewing distance (the distance between the observer's eyes and the center of the screen). You then apply the inverse tangent function (arc tangent or atan) to that result and multiply this by two.

    The reason only half of the image height is used is because you are supposed to line the center of the complete image with your eyes. That half height divided by its distance to your eyes provides the viewable angle when the inverse tangent is applied. It only describes the triangle on half of the image so the other half must be added which is equal to the first since the angles are the same as long as your eyes are lined up with its center.

    For reference: MY RIG currently produces an image height (again counting out the bezels and the rest of the frame of the device; and only measuring the actual display panel) of 53,00cm, with my viewing distance being 89,00cm from the center of the screens, which renders my vFOV at 33º (~33,16º).

    How to calculate the proper vertical FOV (vFOV):

    OBS¹: When I say "viewing distance" I'm meaning the distance from your eyes to the center of the screens.

    OBS²: InvTan (arc tangent or atan) can be found in any scientific calculator. Windows has one which you can set to scientific under file. To use it just press the buttons "Inv" and then "Tan").


    1.2. HORIZONTAL FIELD OF VIEW (hFOV)

    This applies to titles like iRacing that employ a horizontal field of view calculation.

    And going back very quickly to the right triangles, we already know that "A = invTan(a/b)" and that we need to double "A" in order to get the entire screen angle and to halve the width of said screen in order to get to "a". All of that gives us the formula: ScreenAngle = 2 x {invTan x [FullDeviceWidth ÷ (2 x ViewingDistance)]}.

    That means you can simply calculate the total horizontal FOV by multiplying A by 6 instead of only by 2. As in 3 screens times 2. That happens because there are three screens but we are only calculating half of the viewing angle.

    How to calculate the proper horizontal FOV:

    1.3 vFOV ADDENDUM FOR RACEROOM RACING EXPERIENCE

    The vFOV implementation in the SimBin titles has a few particularities.

    One of which is that it only allows you to choose among a set of fixed multiples of its default FOV; which is 58º for single screens and 40º for the triple screens. That is obviously not ideal as it will not let you set your own exact mathematical FOV unless you're lucky enough to fall into one of the nine presets multipliers 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3.

    As said, unless you're lucky to automatically fall into one of the presets an approximation is not good enough. If only you could set your exact mathematical FOV... Oh but wait you can, not within the title, but with some legwork.

    What you have to do is to go to "\Documents\My Games\SimBin\RaceRoom Racing Experience\UserData" and open the "graphics_options.xml" file in the notepad.

    Simply take your mathematical vFOV and divide it by 40. Take this result and place it inside this line


    2. TRIPLE SCREENS' ANGLES

    There is a unfortunate and widespread notion out there that the gMotor2 engine locks the screen angles at 45 degrees.

    This couldn't be more INCORRECT as the gMotor2 engine has never locked the screens at any set angle but quite on the contrary has used a mathematical formula based off your set FOV to calculate what screen angles you should be using.

    This "45º myth" probably started because a "common" distance that a good number of people have their screens at works out to more or less around 45º... And because you'll only start noticing a bigger discrepancy when you either begin going really close or really far away to the screens. Regardless it is definitely set improperly for most of the people and your brain can tell it even if you don't realize right away what it is telling you.

    The higher your FOV the higher the side screen angles you should use.

    It can't be emphasized enough: just like the FOV, the screen angles also are NOT a matter of subjectivity, taste or opinion. They must be set following the application of the MATHS (Mathematical Anti-Telharsic Harfatum Septomin).

    Even for titles that allow for the angles to be customized you should still be using the proper ones that are dictated by the formulae because this way you're ensuring to be at the same distance from all three screens.

    The closer the screens are from you the higher the vFOV, the higher the vFOV the higher the side screen angle, it is all linked together along with your viewing distance and panel's width obviously.

    For reference: MY RIG currently has its screens set at a mathematically dictated angle of 57,50º (~57,52º), with my viewing distance being 89,0cm from triple 97,7cm wide screens.

    How to properly calculate the angles you should set your screens at:

    How to calculate the distance you should sit in order to be able to run certain angles:

    2.1 TRIPLE SCREEN'S ADDENDUM FOR RACEROOM RACING EXPERIENCE

    After many years of waiting RaceRoom Racing Experience has finally received the proper triple screen support it so much needed.

    Again somewhat a convoluted method to set up but it works after the additional necessary legwork.

    Ultimately you'll have to enter a line of arguments containing all the measures and characteristics of your triple screens and rig in the "SET LAUNCH OPTIONS" on the title properties within the Steam Client.

    It's going to look something like this:

    Color coded they stand for:

    OBS¹: I've found that by accounting for the bezels in the nVidia Surround will allow you to fill the argument line with zeros for the bezels. If you don't correct your bezels in the Surround you can choose to do it solely in the argument line, but you'll likely have to account for the Image Width instead of the full Screen Width.

    OBS²: You can use any unit of measurement (inches, cm, mm, etc) as long as you keep it consistent. You can also enter decimals by adding a dot.



    3. ADDITIONAL TIPS AND ADJUSTMENTS

    It goes without saying but in case you're in doubt, yes, the screen bezels' width must be corrected within the NVIDIA or AMD control panels regardless of the other calculations or adjustments in order to achieve a seamless transition between the screens.

    Raise or lower your screens and/or seat in order to align your eye line with the middle of the screens that way you won't be constantly looking up or down in search for the horizon but facing forward in natural line as you should and as you do in real life. Ideally your eye line must align to the middle of the screen up to 20% above of that (or between 50% to 60% up from the bottom of the viewable area) but no more.

    Always¹ try to get AS BIG OF SCREENS AS POSSIBLE and sit as close to it as you can since the closer your eyes will be to the image the lower the FOV you'll be able to use and the best visual experience you will get.

    OBS¹: Catch-22 here! The larger the screen and the closer you sit in relation to it the higher your vFOV will be. And the higher your FOV the higher the side screen angles should be... which can represent a problem after a certain point, say 50" or larger; or if you're sitting "too close" even smaller screens will require attention! When your screen angles begin to get too high you then begin to experience a few problems, most noticeable the worse accessibility in and out of your seat and the increase of reflections from the other screens (better mitigated on projector setups). But not only that as you will now have (depending on your screens' size) a certain amount of your side screens far beyond your field of view, thus potentially keeping locked the full potential of the rig. All the measures talk to each other, always be mindful of that.

    Turn off things like "virtual arms" and "virtual steering wheels", since you already have your real ones in front of your eyes and don't need - not want - to have it doubled...

    Level the horizon for the cockpit view of your cars in your vehicle camera (.CAM) files:

    Remove all the artificial cockpit vibrations in your .PLR files.

    Turn off or set to 0% any look to apex and lock to horizon options you may have in-game or in your .PLR files.

    Stabilize the camera pitch and roll of your cockpit view in your vehicle camera (.CAM) files:

    This is not at all essential but I'd recommend you to customize and to attach some hood and skirts to your screens as it will improve your experience by blocking potential distractions and by eliminating or reducing reflections (and will make your rig look even cooler). I cut MY OLDER ONES out of simple 10mm styrofoam sheets and the NEWER ONES out of 5mm K-Line (card polyethylene foam) wrapped in carbon fiber styled vinyls, but you can use a whole bunch of different materials to achieve similar or even better results.



    4. HOW TO SHOP FOR THE BEST TVS FOR SIM RACING

    TV technology is ever evolving and the larger TVs that once were far too expensive for dedicated simulator use are becoming more and more accessible. PAUSE. I'll still be adding more information on what to look for when choosing the right TV for sim racing as well as how to improve the overall eye candy factor for the various sims.



    That's all for now. Mathematical perfection for practical application at its best!



    Enjoy! ;)
     
    Last edited: Aug 13, 2018 at 4:41 AM
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  2. Dave Stephenson

    Dave Stephenson Administrator Staff Member

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    nice post and a good read.

    One thing that sprung out though is that you do not define 'image height'. It's referenced several times and clearly pointed out that it's not screen height so some clarification on what it is and how to measure it is probably a good addition as it does not seem immediately obvious how those things can differ.
     
  3. GTSpeedster

    GTSpeedster FOV Geek

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    Thanks Dave! ;)

    And as for the "image height" I keep referring to is my poor attempt to differentiate the entire device height (or "screen height" as I think I refer) which would include the frame bezels from the sole image it produces inside the display itself.

    And now that you've pointed that to me I do realize it's really no clear at all, is it? You see English is not my first language and I do get mixed up often. Would you have any suggestions as to what might be a better fit or a more proper use of the words to what I'm trying to refer to?
     
  4. Dave Stephenson

    Dave Stephenson Administrator Staff Member

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    Personally I would immediately think of screen height being what you refer to as image height. My gut feeling is that people would mostly be in the same frame of mind with that purely based on the fact that display devices are typically sold with a size referencing only the visible image size (diagonal of course).

    As to what you might use alternatively I'm not sure what would work best for a wise audience but if you wanted to stay in the language of display devices maybe panel height would be appropriate.
     
  5. Heitor Facuri Cicoti

    Heitor Facuri Cicoti Good Member

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    Well, if words are not that precise, why not use drawings? I volunteer (but after the 24th of July only).
    By the way, I thought of a GIF explaining monitor angles on triples together with FoV.
     
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  6. Ernie

    Ernie Active Member

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    I absolutely agree on that. :)

    Otherwise i don't really understand, why you fully discourage to use the ProjectImmersion site. It's easy to use and works just fine, even if the calculation parameters are more generic. With your screen setup i get a calculated 34°vFOV, which isn't that much off from your own calculation (33,16°vFOV).:confused:
    And for lazy people, which don't want do the math by oneself, it's a simple and usable tool. I'd prefer people using the ProjectImmersion site than driving with a completely wrong FOV.

    However ........ Simracing in VR is the future.:p
     
  7. GTSpeedster

    GTSpeedster FOV Geek

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    I've edited some of it as to try and clarify the terminology. Hopefully it's a bit better... If not please advise! o_O

    I'd be very happy to take you up on that offer if and when you have the time to do it. :D
     
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