VR Headsets' Display Comparison

Hardware & Tech Questions
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This post got significantly edited on 4 August 2019. The original version is kept below for reference only.

Well, after reading through a number of discussions related to FOVs, PPDs, etc. I have to admit I have underestimated the complexity of this issue. Therefore this post is completely re-edited to reflect the most accurate data and methodology “out there”.

Notes to the methodology and sources:

  • All values and calculations are per one eye only (therefore the FOVs are not for the whole HMD but for one eye only).
  • The calculations are done for horizontal as well as vertical FOVs.
  • FOVs are rendered FOVs, so it is an upper limit of what can be seen (i.e. Valve Index’s value is similar to Vive Pro’s but the Index allows to see more of the rendered FOV than the Vive).
  • Rendered FOVs come from a function in OpenVR IVRSystem::GetProjectionRaw which returns the tangents of the angles of the left, right, bottom and top clipping planes for each eye projection. Refer to risa2000 post on pimax forum for further details.
  • Horizontal and vertical rendered FOVs values are sources from a table created by Durante using the OpenVR function above (reddit thread also here). HP Reverb values were sourced from @BeachAV8R on Mudspike forum.
  • I am aware of the ROV room in SteamVR that allows users to measure various qualities of their HMDs. After having read through many discussions and having tried it myself, I decided to disregard this method of assessing the visible FOV in favor of the rendered FOV methodology instead.
  • For Pimax, the vertical rendered FOVs is with parallel projection off.

Known limitations:

  • Panel utilization factor not accounted for.
  • Image warping and optics effects not accounted for (check this thread for more details; nevertheless, the vertical PPD of the Pimax 5k+ in the thread is very close to the one in the table below; not so for the horizontal one though).

And here is the resulting table:

table%20v2
table%20v21015×492 176 KB

Please do read the discussions linked in this post for better understanding of the topic.

Thanks all for contribution. I believe it led to a better result (=table).

Milan

---------- Original post: OBSOLETE ----------

Hi all,

just out of curiosity I made a little table comparing the main VR headsets’ displays in terms of

  • pixel count
  • sub-pixel count
  • pixels-per-degree (PPD)
  • subpixels-per-degree.

The idea came out of a HP Reverb topic where the PPD was discussed as well (by @fearlessfrog):

Resolution on its own does not say much as it needs to be judged together with the FOV (more pixels stretched over wider FOV may equal to less pixels stretched over narrower FOV - in terms of PPD of course).

The methodology (a simple one, this is not rocket science :sunglasses:)

  • resolution and FOV are horizontal
  • Pentile arrangement counts 2 sub-pixels per pixel
  • RGB arrangement counts 3 sub-pixels per pixel
  • binocular FOV is 120 degrees as per the image below; this means that I suppose that both displays show +/- the same FOV for headsets with FOV under 120 degrees; for headsets with FOV higher than 120 degrees the calculation is adjusted to provide for the higher FOV

Human%20Eye%20FOV

The Table

Table
Table1182×241 109 KB

Note: For the Pimax 8K, the table counts with resolution 2560x1440 since this is the resolution to which the picture is rendered and only then it is upscaled to 3840x2160.

Btw. human eye PPD is believed to be around 60.

Well, it seems that the table is an add for the HP Reverb :grinning: but do not forget that the table is just numbers and it disregards other qualities of the headsets.

In case you see an error, please let me know. I am happy to update the table if the need be.

Thanks!

Milan

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Shouldn’t the pixel per degree be for both displays?
The Oculus Rift CV1, for instance, has 1080x2 in horizontal resolution and a 90° FoV. Isn’t that 2160/90=24? Or am I missing something?

Edit. I guess the image overlap both displays… But then again, looking through one eye won’t give you the full FoV. :thinking:
I don’t know.

The FoV in itself is hard to compare between headsets. I have just tried the Rift CV1 and Rift S. The CV1 FoV depends on how I set the IPD sliders and the thickness of the face foam. When I switched to VR Covers thin foam, the lenses got closer to my eyes and FoV increased.
And with the Rift S, that has fixed IPD, the FoV will change with your physical eye IPD.

Also, the quality of the lenses has a big impact on the clarity of the view, but is hard to compare between headsets.

I’m not knocking your comparison here, which is a great baseline. Just adding some thoughts on values that are tricky to compare in a table.

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The assumption is, as per the first picture, that the stereoscopic vision overlap is 60 degrees left and right - giving the 120 degrees combined. So the left eye sees also 60 degrees to the right and vice versa.

I suppose that is also why the HMD manufacturers aim mainly at the FOV around or close below to 120 degrees.

If you look at SBS VR footage, the picture usually shows similar picture for each eye - only it is a bit off for the 3D effect. So again - each eye sees roughly the same FOV.

And yes, what the display shows is not always seen. The percieved FOV depends on the distance of the eyes from the display, and IPD.

Milan

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Indeed.
And here’s where a comparison of FoV gets tricky… It’s very subjective.

When I got the Rift S, my initial experience was that the FoV was smaller than the CV1. But when I went back to the CV1, I concluded that it was more or less the same.

Would be interesting to see a thousand VR users test and score all the different headsets, based on their own preferences.

5

I have just updated the original post:

  • the table now includes also subpixels-per-degree
  • human eye PPD (60) is indicated

The overview could be improved also by adding the vertical dimension - data availability permitting, since some displays apparently offer higher pixel count on rather similar vertical FOV across the headsets.

Or - even better - to calculate pixels / subpixels per square degree, if you see what I mean?

I will try to keep the table updated once new headsets come out.

Milan

6

Original post completely re-edited as of 4 August 2019.

I hope you like it better :+1:

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Sort of on topic…

My Rift S arrived but not the PC, still I did a quick physical check and I discovered something that you all most likely already knew…you can’t see out of the dang thing!

For some reason I thought that it was going to be more like one of those instrument hoods for IFR training…that you could see your desktop area just below the visor.

In watching the Rift S set up video on Youtube, is does show some type of external “see-through” vision for setting up your “play area” (more questions on that later when I get the new rig).

Is it possible to somehow switch between VR and see-through? If not, how does one work their flight controls beyond HOTAS? Cougar MFD in Brailler?

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Muscle memory (for my mouse and MFD bezels), and the nose gap, which is definitely smaller than that of the Rift CV1. But basically it’s a case of perseverance to adapt and overcome. It’s well worth the extra effort.

Oh, and Voice Attack. Worth every penny for a VR pilot.

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If you remove the plastic nose piece at the bottom you will have a small “window” to look though if you need to write something or see a keyboard.

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Yes, but only when using the hand controllers. Can’t be mapped to something else, unfortunately.
The resolution is pretty crap as well.

But as Paul and Kinger says, musclememory and voice attack will take care of most issues, and then there’s the option of removing the nose flap, to be able to peek over the nose.

You could train the Norwegian to handle the keyboard, on your command…? Just a thought.
Mine won’t do it, but your Norwegian seem to be a bit more civilized.

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Troll, you obviously are misinformed as to wears the pants in that family. And no telling what services were bartered for release of gaming funds, especially on the heels of @Hangar200’s J Boat purchase.

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Well, you see, my Norwegian is actually a half Dane, half Norwegian… And I’m Swedish…
So, in one corner you have a fierce Valkyrie and in the other corner there’s a really great neutral diplomat, handy with a IKEA Allen Key.

Oh… You meant the @Hangar200 family.

Too late to retract what I wrote…? :grimacing:

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I shall answer with a quick story…

Its the early 2000’s and I have just purchased a B737 for iFly. This is my first mod with all the bells and whistles including the flight attendant call button. My lovely bride, a former TWA and AA flight attendant, told me the cockpit “bell” code–two bells = call the cockpit, three bells = come to the cockpit (usually to get a coffee or something), etc.

I’ve gone through the 737 start up, taxied, took off and gotten up to cruising altitude…auto pilot on…every thing is going fine…but I’m a little bit thirsty…I could go for a nice cold soda…the wife is in the other room so…let’s see that flight attendant call button in action…

[Bing, Bing, Bing]… nothing…

[Bing, Bing, Bing]… still nothing…

[Bing, Bing, Bing]… then from the other room, “If you think, for one minute, that I’m going to come in there!!…”

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Great, honey! Bring me a soda while you’re at it…

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