Suppose your desk is 36" deep. A 48" wide screen at the back of it occupies 41 degrees of your world. The THX recommendation for cinema is 40 degrees. This is as immersive as you're going to get without strapping a screen to your head.
20/20 vision is about 60 pixels per degree, depending on which study you want to believe. 41x60 is 2460 pixels across -- you've already reached the max required pixels with a 3840x2160 display.
You don’t need a large FOV for movie viewing. Even if it were only 60°, you’d be able see a 2 meter wide screen at a distance of 2 meters (and that’s measuring that distance to the edges of that screen; its center would be about 15% closer)
When it comes to visual acuity for TV watching, doing calculations while basing yourself on their suggested '20/20 vision'=1/60 of a degree, is probably wrong (on average) :
Yes, I've measured my eyes' resolution to be about 60 pixels per degree. I made a black-and-white grid and set it as my desktop picture, with a one-to-one magnification. Then I backed away until I could not discern the pixels. There's even a moire effect, like with cameras, as I reached my threshold. Then I used trigonometry to calculate my angle of view.
Most living-room TVs are probably placed at a 15- to 25-degree angle of view. 1920x1080 is enough for up to a 32-degree horizontal angle of view, which is 7 feet away from a TV with a 55" diagonal, for example. I will say, however, that movie theaters look a little better with 4K, since 30 degrees is supposed to be the back row, and the front row might be 60 or so.
> That should place the headset’s pixels per degree around 50 to 70 PPD.
> “The resolution of the fovea, the highest resolution portion of the eye, is considered to be 60 pixels per degree. And if you have a display like 60 pixels per degree, probably like 99.9 percent of people wouldn’t perceive the pixels”
As a comparison, Quest 2 has a resolution of 20 PPD and sitting in front of a 27" 4K monitor on a desk leads to about 70 PPD.
There are 2 things this page shows, one is the size of screen you need relative on the distance you sit from it based on how much of your view you want it to fill, the other is what resolution the screen needs to be before you have no improvement.
First decide what you want
30 degrees means you'll be able to focus on the picture, but it will fill your focus area, that's recomended by SMTPE
40 degrees is the "immersive" portfolio recommended by THX, you may lose some detail at the edge of the screen depending where you're looking.
Then it's just a bit of trig to work out the size you need for the distance you are sitting (or vice versa), to match your preferred "fullness"
Second is whether you'll benefit from more pixels. They base this on having 20/20 vision and your optical resolution being 1 arc-minute (1/60th of a degree). For comparison the moon is about 30 arc minutues wide.
Seems reasonable to me, if I take a picture of the moon and shrink it to 30px by 30px, I feel it's on par with what I can see in real life.
Then it's just more trig to work out how many pixels you need for a given size/distance combination. A 20" screen that's 10 feet away, you won't be able to tell the difference between SD and HD. A 40 inch monitor 2 feet away and you'll benefit from going higher than 4k. (This assumes a 16:9 aspect ratio).
23M pixels across the field of vision of two eyes doesn't meet the requirements of a design studio. A retina display is minimum 60 pixels per degree. This will be around 30.
The key metric is pixels per degree, which is going to come from both the field of view in VR as well as the monitor resolution.
To put this in Snellen eye chart perspective, in order to read the 20/20 line and distinguish letter details to tell them apart, you have to be able to see details as fine as 1 arc min - 1/60th of a degree.
So basically if your math comes up with less than 60 pixels per degree, you are going to essentially be near sighted inside of the VR environment.
Let's say you have a set of VR goggles with a 140 degree field of view. You need 140 degrees * 60 pixels/degree =8400 pixels to get that same visual acuity as 20/20 vision in real life.
Using HP's new G2 goggles (coming out soon) as an example, they have a screen resolution of 2,160 pixels,and (I've read) about a 100 degree horizontal FOV. That works out to about 22 pixels per degree. Which is about like having 20/55 vision. This is why in VR, you can't read things from a normal distance if drawn to scale. You have to either get closer to them (in VR) or scale them up to make them readable.
You CAN give the user effectively better vision by reducing the field of view. If you don't mind having a 36 degree wide field of view, you'll have 20/20 vision.
20/20 vision is defined as 1MOA, or 1/60th degrees of angular resolution. Necessary resolution at typical FOV of 100 degrees is therefore 6k x 6k pixels. 4k x 4k per eye is not quite the "Retina" equivalent but actually not as off as earlier attempts at VR.
The Vision Pro estimates I've seen are between 33 and 40 PPD (while 20/20 vision is 60 to 70 PPD at the centre of the field of vision). So this could be quite sharp, particularly if you have the text somewhat larger (on the huge virtual monitors) than you'd normally have it.
Ultimately what we care about when it comes to resolution is “pixels per degree of viewing angle while at the optimal viewing distance”.
The screen has some fixed pixel density, using called PPI or DPI. As you sit closer or further away, the screen will cover greater or fewer degrees of your field of vision (I recommend looking up diagrams to get a better understanding of this concept). You can thus combine a screen’s physical pixel density with your distance from the screen to get a single number called “PPD”, pixels per degree, that represents how many pixels fit into one degree of your field of view. As a reference point to contextualize this number: the “Retina display” popularized by Apple is based on the claim that at 300DPI, the eye can no longer pick out individual pixels on phone screens usually held at 10-12 inches away. This corresponds to a PPD of 57. Higher PPD is better but it tapers off: going from 50 to 100 PPD is “visible individual pixels vs high end Retina”, while the difference between 1,000 PPD and 10,000 PPD is nothing (we are well beyond human eye capabilities and both would look the same).
THX (from the cinema industry) gives us some numbers on optimal FOV - how much of your field of vision the screen should take up, measured in degrees. The maximum is 70 degrees (fills your field of view out to the edges of your peripheral vision), the optimal is 40 degrees, and the minimum is 26 degrees.
I’m on an iPhone 14 Pro and according to my tape measure I am holding it 20cm away from my eyes (FOV of 39 degrees), which gets me a PPD of 66. If I sit down at my computer which is a 13in 2020 MacBook Pro M1, my tape measure says 60cm from eye to screen, giving me a 27 degree FOV and a PPD of 95.
My tape measure says it’s 250cm from my eye to my TV, so let’s look at some 4K and 8K options. Samsung makes 4K and 8K screens in 65in, 75in, and 85in screen diagonals.
65in 4K: 120 PPD, 32 degree FOV
75in 4K: 105 PPD, 37 degree FOV
85in 4K: 93 PPD, 41 degree FOV
65in 8K: 239 PPD, 32 degree FOV
75in 8K: 209 PPD, 37 degree FOV
85in 8K: 186 PPD, 41 degree FOV
So is it worth it? Only if you want to sit so close that the screen fills your entire field of view.
To be honest, I’m not an expert, and you’d just be getting a lay opinion. They say human vision can discern about 60 pixels per degree. I believe Quest Pro achieves about 20, and Project Cambria might push 30.
I did a napkin math a while back: the standard for 20/20 vision or 1.0 acuity scale equals to 1 arc minute resolution, or 1MOA, or an Euclidean angle of 1/60th degree.
A spherical VR image that resolves to 20/20 acuity is as large as (60 x 360, 60 x 180) = (21600, 10800)px before requisite oversampling, and that’s kind of hard. Then of course those fighter guys has/need better visibility than 20/20 which only makes it harder.
And by the way modern digital image pipelines buffer and delay transfers, sometimes as much as 200ms, which is absurd considering the CPU runs at literally millions of times better clock frequencies and latencies, but that’s what readily available implementations are.
These mean that we are still some time away until such “local remote driving” not just complements but totally replace heat formed and dielectric coated pane of plexiglass.
I guess it eventually will beyond upper edge of atmosphere as glasses don’t work well and vision required surpass human eyeballs, i.e. in interstellar settler’s carriages and planetary orbital fighter jets, but for now and for forward windscreen applications, it makes more sense to just put on panes of plain old transparent aluminum.
> a whopping 60 degrees which is considered high for just consuming content, much less playing a game where you're expected to see everything happening on screen and react to it.
Consider that the game is probably rendering at least 90 degrees to squish down into that 60.
Personally I sit back for content but I love to sit close for games, with the FOV set to max. The really important stuff fits in the middle of the screen, and outside of the middle I get near-peripheral vision instead of bezel and wall.
20/20 vision is about 60 pixels per degree, depending on which study you want to believe. 41x60 is 2460 pixels across -- you've already reached the max required pixels with a 3840x2160 display.
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