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Comment by Retric | Hacker News Reader

"5120 x 5120 at 60 fps" here is why that's overkill. If you start putting dots on a sphere you can go in one direction turn 90 degrees, put 5120 another axis. However, if you tile like that with 5120 x 5120 you get a lot of wasted pixels at the poles.

If a 5120 pixel Radius is fine... then Radius of sphere = 2 pi * r, and Surface of sphere is 4 pi * r^2. So 5120 / 2pi =r substitute for r > 4 * (5120/2pi)^2 simplify > (5120)^2 /(pi) ~= we need ~1/3 aka 1/pi of 5280^2.

However, I suspect you actually want more than 5120 pixel radius.

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In the center of the lenses, the circumference resolution is a bit over 5120, but definitely less than 5760. Even at 5120, it is a bit overkill (and potentially aliasing) at the edges: https://twitter.com/ID_AA_Carmack/status/975198157838499840

You are off by a factor of 2 in your pixel calculation, because 5k x 5k is for a stereo pair of spheres. Equirect projections waste a fair amount, but compared to the 300% miss to get to 60 fps stereo, it isn't dominant.

Ahh, good to know.

Anything you can do about someone tilting their head? That feels like the biggest remaining immersion breaker with pre-rendered stereoscopic videos.

Need some form of RGB+D for that. I have a player for that, and sometimes it looks fantastic, but the silhouette edge artifacts can sometimes look really bad. Considering some ways of "relaxing detail around the edges".

Would we ever see a dynamic resolution that tracks where you are looking at and just lowers resolution outside the point of interest? Wouldn't that save a lot?

https://en.wikipedia.org/wiki/Foveated_rendering

I thought I was smart for just 10 seconds of my life... thanks for the link

In the mid-90s I worked on a system that did that to maximize image processing power, CCTT: https://www.youtube.com/watch?v=HY5M1jM5ggw

The article is about doing that for pre-recorded video. For live 3D VR rendering, it's already in some game engines. Batman Arkham VR uses it (it's in the settings). More info https://www.youtube.com/watch?v=gV42w573jGA

> If you start putting dots on a sphere you can go in one direction turn 90 degrees,

Starting where? Turning where?

> However, if you tile like that with 5120 x 5120 you get a lot of wasted pixels at the poles.

You didn't mention tiling.

> If a 5120 pixel Radius is fine... then Radius of sphere = 2 pi * r, and Surface of sphere is 4/3 pi * r^2. so 5120 / 2pi =r => 4/3 * (5120/2pi)^2 => (5120)^2 /(3 pi) ~= we need ~10% of 5280^2.

More details on what you are trying to say at each step please.

Quick edit, it's 4pi r I was thinking volume for a second there.

As to tiling, I am saying if cut a sphere into 5120 slices, and the middle slice is fine with 5120 pixels. Then the poles are going to have ~1 pixel on them. How you tile them is really a question of tradeoffs.

I think you should draw a diagram and link it.

> As to tiling, I am saying if cut a sphere into 5120 slices, and the middle slice is fine with 5120 pixels.

What kind of slices? Like sections of an orange? Like longitude?

I was thinking lines of latitude.

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