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Comment by potatolicious | Hacker News Reader

There's no precise criteria but the usual measure is ppd (pixels per degree) and it needs to be high enough such that detailed content (such as text) displayed at a reasonable size is clearly legible without eye strain.

> "Could you not just move your face closer to the virtual screen to see finer details?"

Sure, but then you have the problem of, say, using an IMAX screen as your computer monitor. The level of head motion required to consume screen content (i.e., a ton of large head movements) would make the device very uncomfortable quite quickly.

The Vision Pro has about ~35ppd and generally people seems to think it hits the bar for monitor replacement. Meta Quest 3 has ~25ppd and generally people seem to think it does not. The Steam Frame is specs-wise much closer to Quest 3 than Vision Pro.

There are some software things you can do to increase legibility of details like text, but ultimately you do need physical pixels.

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Even the vision pro at 35ppd simply isn't close to the PPD you can get from a good desktop monitor (we can calculate PPD for desktop monitors too, using size and viewing distance).

Apple's "retina" HiDPI monitors typically have PPD well beyond 35 at ordinary viewing distances, even a 1080p 24 inch monitor on your desk can exceed this.

For me personally, 35ppd feels about the minimum I would accept for emulating a monitor for text work in a VR headset, but it's still not good enough for me to even begin thinking about using it to replace any of my monitors.

> https://phrogz.net/tmp/ScreenDensityCalculator.html

Oh yeah for sure. Most people seem to accept that 35ppd is "good enough" but not actually at-par with a high quality high-dpi monitor.

I agree with you - I would personally consider 35ppd to be the floor for usability for this purpose. It's good in a pinch (need a nice workstation setup in a hotel room?) but I would not currently consider any extant hardware as full-time replacements for a good monitor.

Most people in what age group?

I'm 53 and the Quest 3 is perfectly good as a monitor replacement.

Are you saying ppd requirements for comfortable usage vary with age?

They vary with quality of eyesight which usually correlates with age.

I'm in the same boat. Due to my vision not being perfect even after correction, a Quest 3 is entirely sufficient.

I keep hearing this argument, and it baffles me. I find that, as I age and my vision gets worse, I need progressively finer text rendering. Using same-size displays (27") at the same distance, with text the same physical size on screen, 1440p gives me a much worse reading experience than 4k with 2x scaling.

We get by with lower resolution monitors with lower pixel density all the time.

I'm not sure most of us do anymore - see my 1080p/24 inch example.

No one who has bought almost any MacBook in the last 10 years or so has had PPD this low either.

One can get by with almost anything in a pinch, it doesn't mean its desirable.

Pixel density != PPD either, although increasing it can certainly help PPD. Lower density desktop displays routinely have higher PPD than most VR headsets - viewing distance matters!

I think part of getting by with a lower PPD is the IRL pixels are fixed and have hard boundaries that OS affordances have co-evolved with.

(pixel alignment via lots of rectangular things - windows, buttons; text rendering w/ that in mind; "pixel perfect" historical design philosophy)

The VR PPD is in arbitrary orientations which will lead to more aliasing. MacOS kinda killed their low-dpi experience via bad aliasing as they moved to the hi-dpi regime. Now we have svg-like rendering instead of screen-pixel-aligned baked rasterized UIs.

I think there is a missing number here: angular resolution of human eyeballs is believed to be ~60 ppd(some believes it's more like 90).

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