# Max resolution for VR

#### camhops360

##### Commendable
Right now I have a PS4VR and Gear VR

At what point does the photo/video resolution become greater than the headset resolution?

I understand the photos and videos are stretched in 360x180. So would you still see additional detail at 8k or is 4k the max resolution?

#### Sakkura

##### Distinguished
The 360 degree cameras have their resolution spread across the entire sphere (more or less). You can't see all that in any VR headset, you only see the part that's in your field of view.

So if the overall 360 video has an 8K resolution, you'll be looking at a smaller cone of that with considerably less than 8K resolution. If we assume the VR headset has a 110 degree field of view, you can only see about 21% of a full sphere.

I'm not entirely sure how 8K resolution is defined for 360 degree video (it can't be quite the same as 16:9 8K, AKA 7680x4320, since a sphere is not 16:9), but assuming you have the same number of pixels... the cone you see would contain about 7 million pixels in the video signal. The HTC Vive and Oculus Rift have a per-eye resolution of about 1.3 million pixels, for comparison. So in that sense, 8K 360 video ought to provide the best possible video resolution those headsets can show. More pixels in the video won't help since the headset is the limiting factor.

If you want to calculate yourself, the part of a sphere a headset shows is (1-cosθ)/2 - where θ is half the headset's FOV. Then you can multiply that number by the video resolution to get how many pixels the video has available for the headset. If that number is much higher than the per-eye resolution of the VR headset, then the headset is the limiting factor. If it's about the same or lower, then increasing the video resolution can still improve perceived visual quality.

#### photonboy

##### Distinguished
Gear VR uses a slide-in phone AFAIK so it's the resolution of that, and even then it's complicated because it's only using part of the screen for each eye and warping the image.

You then get an "effective resolution" since it's in 3D.

PS4VR is only a 1920x1080 screen with half of it (960x1080) per eye so I'm not sure if that's more or less than a 1920x1080 screen but it's nowhere near 4K resolution.

The only way to benefit from 4K or greater pictures would be if you ZOOM IN on the image.

#### camhops360

##### Commendable

I guess my question is what are the max amount of pixels you are surrounded by? The 1920x1080 is only in one FOV.

What are the max amount of pixels you can see when looking around the entire envionment with the VR headset.

#### Tri23

##### Respectable
I FIGURED IT OUT! (you are not gonna like the answer.)

First.. you need to define the problem.
"what are the max amount of pixels you are surrounded by?"

Shape:
- Max would be a spherical image. (versus just a 360 cylidrical shape.)

Distance:
- You are talking VR here, so how big is the sphere?
Size = Radius to the viewer.

Resolution
- what is the max resolution possible from any camera for VR?
Right now it looks like 4k from a Hero-Black stiched together. If somebody can find better, let me know.
Even then, I am not sure you can get a sphere with the current product.. (but I didn't search too hard.)
https/shop.gopro.com/odyssey

You know what.. let's just say you own your own software dev studio and they can stitch any number of camera images.

But...
You still need to render this sucker! That stated.. visual stuff can be scaled in the cloud, so let's just assume that it is possible. Rendering may just take a REALLY long time....

So let's take this to the extreme...
- You have a highly finite number of Hero-black Go-Pros.
- Attached to a highly finite mounting VR rig in space (which you 3d printed in space.)
- Attached to the worlds most powerful cloud computer. (yeah, you own Amazon.)

MAX Pixels =
3840 x 2160 X #of Cameras.

Sooo.. the answer is INFINITE! (theoretically.)

Think of it like Google Earth VR if the entire world was just one single image, and you were literally zooming in on parts of the image.

#### Tri23

##### Respectable
Note!

If you limit the radius to the HMD, then you limit the size of the sphere, and then...
- Take the surface area of the sphere.
- Determine the DPI of the sphere.
- Calculate the number of max pixels of that sphere.

This isn't exact.. but I think it is pretty spot on.

#### camhops360

##### Commendable

The Insta 360 Pro can take 8k 360 photos and video. It can also capture 6k 3d 360 photos and videos.

PSVR and Gear VR (the ones I mentioned)

Or Oculus

How many pixels can you see fully immersive? Does this info exist? I can't find it. I don't know if 8k is worth the money if no headset can see all the pixels spread out (fully immersive 360 x 180)

#### camhops360

##### Commendable

Let me be more specific. If I buy an 8k 360 3d camera (like the Insta360 Pro) would it be possible for me to see all pixels in 8k resolution in a fully immersive environment using a mainstream VR headset (Vive, Oculus, Gear VR, or PSVR).

If not at what resolution is there a diminishing return? If no mainstream VR headset can render 8k in 3d/360 (360x180) what is the max resolution?

#### Sakkura

##### Distinguished
The 360 degree cameras have their resolution spread across the entire sphere (more or less). You can't see all that in any VR headset, you only see the part that's in your field of view.

So if the overall 360 video has an 8K resolution, you'll be looking at a smaller cone of that with considerably less than 8K resolution. If we assume the VR headset has a 110 degree field of view, you can only see about 21% of a full sphere.

I'm not entirely sure how 8K resolution is defined for 360 degree video (it can't be quite the same as 16:9 8K, AKA 7680x4320, since a sphere is not 16:9), but assuming you have the same number of pixels... the cone you see would contain about 7 million pixels in the video signal. The HTC Vive and Oculus Rift have a per-eye resolution of about 1.3 million pixels, for comparison. So in that sense, 8K 360 video ought to provide the best possible video resolution those headsets can show. More pixels in the video won't help since the headset is the limiting factor.

If you want to calculate yourself, the part of a sphere a headset shows is (1-cosθ)/2 - where θ is half the headset's FOV. Then you can multiply that number by the video resolution to get how many pixels the video has available for the headset. If that number is much higher than the per-eye resolution of the VR headset, then the headset is the limiting factor. If it's about the same or lower, then increasing the video resolution can still improve perceived visual quality.

#### photonboy

##### Distinguished

I've already tried to explain what the maximum resolution is. The PSVR again is closer to an HDTV as it's 1920x1080 (same number of pixels) but you only see half per eye (less really the way the lens works) and it's stitched back together so there's OVERLAP thus you probably don't get a full 1920x1080 since images need common data so likely BETWEEN 960x1080 and 1920x1080.

*I can tell you that if you get a 4K screen, and get a high-quality image as you move closer to it the image looks pretty amazing even when it's close to filling your field of view.

8K (about 7,680 x 4,320 pixels) when you stand close is supposedly about as sharp as you can get (note you can't focus on all the pixels at once when it's filling your vision), though experts say you can see 16K which is 4x even that resolution (but such diminishing returns it's hard to tell without extensive testing).

That's 2D so I suppose there's still some benefit to HALF of 16K per eye (which is not the same as 2x8K)

In VR we do stuff like WARPING the data so it gets BLURRED when off of our direct field of view to save on processing.

So if you want the MAXIMUM RESOLUTION it's probably very roughly something like:

16K screen (half viewable per eye).

*But again, there's factors like:
1. An 8K camera doesn't mean it's got the same quality as another 8K camera. Resolution isn't a direct indicator of quality. There are very high quality 4K cameras that may look better.

2. Are you ZOOMING in to the image?
If so, then you can't practically buy a camera with sufficient quality (and storage space) for that depending on how much you zoom in.

So... Huh?

CAMERA?
I think practically speaking if the camera is at least "4K" (even if half per eye in 3D) and very high quality that's more than sufficient for your purposes.

The diminishing returns of camera quality, pixel benefit to the eye and finally the lack of super high-res HUD's means there's no use getting hung up too much beyond again, quality 4K/8K 3D cameras.

#### aquielisunari

##### Distinguished
And then there is 2.5 supersampling.

#### photonboy

##### Distinguished

Any technique you apply to VIDEO content will degrade it. There are techniques like Supersampling which may be a good idea for GAMES to reduce processing power to get a similar quality image (everything is a trade-off between visual fidelity and processing power) but displaying back video content is relatively simple.

I'm no expert on this, but at the very least I don't think it affects the choice of camera. There's a very close correlation between pixel count in the video frame and how many "pixels" we can actually see (or at least focus on at one time).

#### Sakkura

##### Distinguished

When you watch a 360 video in a VR headset, you are automatically "zooming in" on a particular section. Neither your eyes nor your VR headset have a 360 degree field of view, so you will always be looking at just a small section of the video.

This is why 4K isn't necessarily optimal for a 360 video, even though 4K is much higher resolution than typical VR headsets currently on the market; the video will have considerably less resolution for the part you actually end up looking at.

#### photonboy

##### Distinguished

Not sure that's really true.
I've made 360deg photos in the past and the one I made was stitched together out of at least TWENTY different photos, then of course warped slightly as it rotates. The resolution (and quality) was still higher than what a normal HUD could benefit from at any given time during rotation.

I was always looking at a minimum of one 4K image and at least two partials merged together.

I don't think there's much reason to get hung up on the specifics though. Get a quality 4K camera, but I wouldn't bother with "8K" necessarily unless there's an obvious benefit.

A high quality 4K image or video on a quality 4K HDTV looks pretty amazing even when you're close enough to mostly fill your entire view.

VIDEO and PICTURE QUALITY isn't directly comparable to the number of pixels you can generate. There are 4K cameras of better quality than 8K cameras. So you need to do your research. Low-light conditions for example can look very grainy and dark if the camera sensor isn't good enough for that.

#### Sakkura

##### Distinguished
I definitely agree about pixel counts not being the whole story. The stitching is very important, as is the general camera quality.