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Just because it's the highest PPD doesn't mean the resolution is actually all that high. Resolution has always been my main complaint about VR headsets and the

Just because it's the highest PPD doesn't mean the resolution is actually all that high. Resolution has always been my main complaint about VR headsets and they are nowhere near the PPD needed to simulate watching high resolution content on a high resolution screen in front of you yet. The Vision Pro is supposed to have 23MP, and an aspect ratio of 1.165:1 which suggests 3660 pixels across each eye. However, what most people fail to think about is the FOV. The headset's entire FOV is about 100 degrees horizontally. THX standards recommend around 35 degrees for video horizontal FOV, but if people like a really immersive FOV for their video I think it's safe to push this up to around 50 degrees. This means that a virtual theater screen within your FOV on the headset has only half the headset's resolution to work with. So that makes the width of a virtual 50 FOV horizontal screen 1830 pixels wide, which is less than even 1080p video at 1920 pixels wide. And this is probably a bit high too as there is typically some amount of pixels you can't even see through the lens of a VR headset because you don't normally want to be able to see the edge of the panel inside the headset. Rather you see the edge of the optics. So that 3660 panel width is probably more like 3460, then divide that in half to 1730 pixels wide for your virtual screen. And that's if you like a 50 FOV wide virtual screen. That would be like sitting 5 feet away from a 65" TV which is arguably closer than the vast majority of people sit. So if you are watching video at a pretty immersive 50 degree FOV, in an Apple Vision Pro, the native resolution of the video needs to only be about 1730x973 (assuming 16:9 video) at most to max out the PPD of the headset for reasonably sized virtual video screens.

dagmx 3y ago
That’s all well and good (and good info) but you’re not factoring in pixel alignment. There’s loss because you need to account for the video being at a non-aligned offset at any given view from the native screen pixels, and the video may be presented at different planar angles or distances from the user. Therefore there would be some level of interpolation causing loss of clarity. In general, you’d want to double resolutions as a form of super sampling. The 1080p here would be just about cutting it then at the initial 35 degrees you mentioned. I think for the natural FoV of the phone camera and the types of content people tend to shoot (families etc) that a 50 degree view might be uncomfortably large. Perhaps for further afield content like landscapes etc
- SirMaster 3y ago
  I guess I'm not sure why the video should need to be higher resolution for super-sampling than the pixel space it will be rendered on. Why it would need to be higher resolution than the native pixel space that the virtual screen will be rendered over? Changing the angle or rotation of your head to the virtual screen only makes the virtual screen technically even lower resolution, and would make it so that you would notice an even lesser difference between higher and lower resolution videos being played on that virtual screen. I chose 50 FOV because I think it's reasonable near upper-bound. I am heavily into home theater, and I have tried various VR headsets to replicated a home theater projector setup. Personally I am a fan of sitting to my projector (or TV) screens where the width of the screen is equal to my viewing distance. This results in a horizontal FOV of 53.1 degrees. Now I often invite people over to my theater, or travel around and visit other people's HTs and I have found that most HT enthusiasts have no problems with this rough screen width-to-distance FOV for viewing movies. However maybe HT enthusiasts are not very representative of the masses, but anyway I was only using it as more of an upper-bound and what I have been looking for in a headset. If I want a virtual HT screen that has the native resolution of at least 1080p, and the headset has over 100 degree FOV (which most do), then I see that I need a headset to have more than 4000 pixels wide per eye, which sadly just doesn't exist yet. But, at least in my experience, I don't think the resolution of the video itself needs to be substantially higher than the pixel space of the virtual screen. I think that regular real-time machine learning video up-scaling techniques are sufficient enough these days to render the video in a way that wont cause bad artifacts when the virtual screen pixels are skewed because the headset wearer is tilting or turning their head in relation to the position of the virtual screen. Now I am fully aware that VR signal input also needs to be a higher resolution source than the native headset pixels, because there is some warping done to the image to make it look correct through the lenses, but that should only need to be applied to the 3D environment space the user is seeing. That means that the video being imposed into the virtual screen simply needs to be stretched via up-scale to a higher resolution and then this will be downscaled via the headset warp more or less back to its native resolution. But what you are saying does make sense and I am sure is somewhat of a factor. But then also, lower resolution video can still look quite fine once there is enough pixels to get good detail.

dagmx 3y ago

That’s all well and good (and good info) but you’re not factoring in pixel alignment. There’s loss because you need to account for the video being at a non-aligned offset at any given view from the native screen pixels, and the video may be presented at different planar angles or distances from the user. Therefore there would be some level of interpolation causing loss of clarity. In general, you’d want to double resolutions as a form of super sampling. The 1080p here would be just about cutting it then at the initial 35 degrees you mentioned. I think for the natural FoV of the phone camera and the types of content people tend to shoot (families etc) that a 50 degree view might be uncomfortably large. Perhaps for further afield content like landscapes etc

SirMaster 3y ago
I guess I'm not sure why the video should need to be higher resolution for super-sampling than the pixel space it will be rendered on. Why it would need to be higher resolution than the native pixel space that the virtual screen will be rendered over? Changing the angle or rotation of your head to the virtual screen only makes the virtual screen technically even lower resolution, and would make it so that you would notice an even lesser difference between higher and lower resolution videos being played on that virtual screen. I chose 50 FOV because I think it's reasonable near upper-bound. I am heavily into home theater, and I have tried various VR headsets to replicated a home theater projector setup. Personally I am a fan of sitting to my projector (or TV) screens where the width of the screen is equal to my viewing distance. This results in a horizontal FOV of 53.1 degrees. Now I often invite people over to my theater, or travel around and visit other people's HTs and I have found that most HT enthusiasts have no problems with this rough screen width-to-distance FOV for viewing movies. However maybe HT enthusiasts are not very representative of the masses, but anyway I was only using it as more of an upper-bound and what I have been looking for in a headset. If I want a virtual HT screen that has the native resolution of at least 1080p, and the headset has over 100 degree FOV (which most do), then I see that I need a headset to have more than 4000 pixels wide per eye, which sadly just doesn't exist yet. But, at least in my experience, I don't think the resolution of the video itself needs to be substantially higher than the pixel space of the virtual screen. I think that regular real-time machine learning video up-scaling techniques are sufficient enough these days to render the video in a way that wont cause bad artifacts when the virtual screen pixels are skewed because the headset wearer is tilting or turning their head in relation to the position of the virtual screen. Now I am fully aware that VR signal input also needs to be a higher resolution source than the native headset pixels, because there is some warping done to the image to make it look correct through the lenses, but that should only need to be applied to the 3D environment space the user is seeing. That means that the video being imposed into the virtual screen simply needs to be stretched via up-scale to a higher resolution and then this will be downscaled via the headset warp more or less back to its native resolution. But what you are saying does make sense and I am sure is somewhat of a factor. But then also, lower resolution video can still look quite fine once there is enough pixels to get good detail.