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It mentions "...5120 pixels across 360 degrees is a good approximation. Anyone over this on current VR headsets is simply wasting resources and inviting aliasin

It mentions "...5120 pixels across 360 degrees is a good approximation. Anyone over this on current VR headsets is simply wasting resources and inviting aliasing." How does increasing the resolution cause aliasing? Shouldn't it be the opposite?

AboutTheWhisles 8y ago
He did not say it causes aliasing, he said it is inviting aliasing. More resolution is going to be fine if the pixels are filtered well. If they aren't, that could certainly invite aliasing. Pixel filtering, especially in a scenario like this, is going to have a wide spectrum of techniques that can work to varying degrees, with trade offs of quality and speed.
- gmueckl 8y ago
  A pixel filter that takes into account the highly nonregular shape of the projected screen pixels and the warped projected video pixels in the source at the same time would be quite an interesting task.
- jpambrun 8y ago
  I think the point was mostly if you are filtering to downsample, you should probably not have downloaded the bytes or have wasted the energy decoding.
  - AboutTheWhisles 8y ago
    The question I was replying to was about aliasing.
gmueckl 8y ago
Aliasing happens only when the signal that you are sampling has higher frequencies than what you can represent in your sampled data. So he is absolutely correct here: if the source material has higher resolution, the projection onto the lower resolution display would lead to the same kind of undersampling. Basically, you'd miss in-between pixels and if these have significant content, it becomes very noticeable (e.g. parts of very thin features missing from the image).
cptskippy 8y ago
Today's VR Headsets are low resolution. If your video source is higher resolution than the display then it must be downsampled. Downsampling will introduce aliasing artifacts unless an anti-aliasing pass is preformed prior to downsampling. > Image scaling can be interpreted as a form of image resampling or image reconstruction from the view of the Nyquist sampling theorem. According to the theorem, downsampling to a smaller image from a higher-resolution original can only be carried out after applying a suitable 2D anti-aliasing filter to prevent aliasing artifacts. The image is reduced to the information that can be carried by the smaller image. - https://en.wikipedia.org/wiki/Image_scaling https://en.wikipedia.org/wiki/Image_scaling In an ideal situation, your source resolution would match your target resolution. If it doesn't then you must expend resources scaling. VR can't leverage the 2D scalers found in most hardware since the source data is being mapped into 3D space. If you have to downscale your source then on top of the processing resources being used to scale in 3d space, you're also wasting bandwidth delivering those resources at a higher resolution.
- stefan_ 8y ago
  Eh is it wasting memory bandwidth, sure, but let's not pretend a modern smartphone GPU is breaking much of a sweat rendering some 5k textures into a >x framebuffer.
  - cptskippy 8y ago
    If the video is streamed it's wasting internet bandwidth as well. If not then device storage. High end mobile GPUs can handle 5k video at the expense of battery life but most GPUs can't.
- wonderlady 8y ago
  I really don't like the idea that it's good enough now since the headset block us. Technology innovation can come from every area. If others make better 360 cameras or players and exceed the 5K experience, they should not considered as "wasted" just because one kind of display headset doesn't meet the same level. I do like Oculus Go for its nice price and acceptable experience. But there are quite some headsets that perform better, at least capable to display 8K or even above, Vive Focus, Gear VR with S8 and S9, and the upcoming Pimax. So, please don't block others and ourselves on technology innovation! Eventually if we take human eyes as the ideal benchmark, we need to achieve 16K!

AboutTheWhisles 8y ago

He did not say it causes aliasing, he said it is inviting aliasing. More resolution is going to be fine if the pixels are filtered well. If they aren't, that could certainly invite aliasing. Pixel filtering, especially in a scenario like this, is going to have a wide spectrum of techniques that can work to varying degrees, with trade offs of quality and speed.

gmueckl 8y ago
A pixel filter that takes into account the highly nonregular shape of the projected screen pixels and the warped projected video pixels in the source at the same time would be quite an interesting task.
jpambrun 8y ago
I think the point was mostly if you are filtering to downsample, you should probably not have downloaded the bytes or have wasted the energy decoding.
- AboutTheWhisles 8y ago
  The question I was replying to was about aliasing.

gmueckl 8y ago

Aliasing happens only when the signal that you are sampling has higher frequencies than what you can represent in your sampled data. So he is absolutely correct here: if the source material has higher resolution, the projection onto the lower resolution display would lead to the same kind of undersampling. Basically, you'd miss in-between pixels and if these have significant content, it becomes very noticeable (e.g. parts of very thin features missing from the image).

cptskippy 8y ago

Today's VR Headsets are low resolution. If your video source is higher resolution than the display then it must be downsampled. Downsampling will introduce aliasing artifacts unless an anti-aliasing pass is preformed prior to downsampling. > Image scaling can be interpreted as a form of image resampling or image reconstruction from the view of the Nyquist sampling theorem. According to the theorem, downsampling to a smaller image from a higher-resolution original can only be carried out after applying a suitable 2D anti-aliasing filter to prevent aliasing artifacts. The image is reduced to the information that can be carried by the smaller image. - https://en.wikipedia.org/wiki/Image_scaling https://en.wikipedia.org/wiki/Image_scaling In an ideal situation, your source resolution would match your target resolution. If it doesn't then you must expend resources scaling. VR can't leverage the 2D scalers found in most hardware since the source data is being mapped into 3D space. If you have to downscale your source then on top of the processing resources being used to scale in 3d space, you're also wasting bandwidth delivering those resources at a higher resolution.

stefan_ 8y ago
Eh is it wasting memory bandwidth, sure, but let's not pretend a modern smartphone GPU is breaking much of a sweat rendering some 5k textures into a >x framebuffer.
- cptskippy 8y ago
  If the video is streamed it's wasting internet bandwidth as well. If not then device storage. High end mobile GPUs can handle 5k video at the expense of battery life but most GPUs can't.
wonderlady 8y ago
I really don't like the idea that it's good enough now since the headset block us. Technology innovation can come from every area. If others make better 360 cameras or players and exceed the 5K experience, they should not considered as "wasted" just because one kind of display headset doesn't meet the same level. I do like Oculus Go for its nice price and acceptable experience. But there are quite some headsets that perform better, at least capable to display 8K or even above, Vive Focus, Gear VR with S8 and S9, and the upcoming Pimax. So, please don't block others and ourselves on technology innovation! Eventually if we take human eyes as the ideal benchmark, we need to achieve 16K!