Oculus Resolution, Render Scale, And All That

Something I am struggling with despite reading enumberable posts is the relationship between the Oculus headset native resolution, the resolution setting in the Oculus App, and Render Scale.

Can anyone illuminate?

The occulus headset resolution is 1832 x 1920 per eye - does the Oculus App resolution relate to per eye or the two combined?

Even if it is the latter, the max setting in the app is still way higher than the headset resolution - is this where render scale comes in - i.e. if you set the in-app res high you set the render scale below 100 to match the headset - the idea being that you are leveraging the GPU more to higher fidelity and then down scaling?

What happens when the in-app res X the render scale doesnt match the headset - presumably the GPU adjusts it to fit?

What does a render scale > 100 do? Is this for when the in-app res is low for a lower spec GPU?

i9-11900K
RTX 3080 ti
64 GB
Oculus Quest 2

1 Like

This link will give you a start on the answer about the relationship between the native resolution of the Oculus and the slider.

And this, which is the top of the thread, reveals what the oculus slider does.

Iā€™ll let someone more experienced than me answer your other questions.

Wow - thatā€™s useful info about the need to generate a curved image - so you only get the max detail if you push the slider all the way. I wonder if render scale is just an in game way of altering the resolution - Iā€™ll try that.

With your specs you should be able to achieve maximum resolution in Oculus app 5472*2736 and 100 render scale in game, thatā€™s what I use. As per the post above I believe this is the closest thing to ā€œnativeā€ resolution. Then if you want more performance, adjust down either the Oculus resolution or the render scale - there are many threads with recommendations about combinations but I donā€™t think there is an accepted ā€œbestā€ combination.

With regards to what is happening, my understanding is the Oculus app sets the virtual resolution of the ā€œdeviceā€, and then MSFS sees a device with this resolution and will render at this resolution when you set 100 render scale. MSFS will generate super sampling if you set a render scale above 100, and will perform a kind of upscaling if you set below 100(rendering at a lower resolution but then applying its sharpening filters etc). Interested to hear a proper explanation from someone who knows this stuff properly though :slight_smile:

Thanks RebuffedBee

I found that at max res and 100 renderscale and everything else on ultra, the sim would bounce around 30 to 35 FPS with major stuttering due to all the dropped frames, so I have been pursuing a frame rate tuning strategy.

My test area has been Chicago with low level flying.

Pining the FPS to 30 with the above gives excellent results above 3000ft - below that and thereā€™s not enough FPS to render things smoothly. Also, 30 FPS results in a low FPS blur when manaoeving too quick - but it aint bad.

I also note that I am main-thread bound on the PC and so this has factored into my tuning strategy as well - looking for that to be bouncing into the green.

Adjusting the MSFS VR graphics settings has little to no affect on the above constraints - which is of no surprise I guess as they are all GPU things and the setup at max settings is CPU bound - I do notice the effects of reducing them on image quality and GPU load - so I just leave everything on ultra.

So where I went from there was to find the FPS sweet spot that allowed for low level flying and eliminated the worst of the low FPS effects. That is looking to be a min of 40 FPS at the moment. So now I am looking at the highest res that will not drop frames at 40 FPS and keep me on that only-just cpu bound edge.

Hence my question about the balance between resolution and render scale - is it better to pin the render scale at 100 and find the max res for 40 FPS or is there some benefite in allowing a lower render scale to get a higher res?

Iā€™m watching this thread very closely; thanks for verbalizing the same question I had in a way that makes sense - thereā€™s no way I could have.

Something I have been looking at is whether render resolutiuon set in the oculus app and render scale set in MSFS result in an ā€˜equivalentā€™ product.

My test was to run with a render resolution of 4192 in the app and a render scale of 100 (i.e. x1) in MSFS versus max resolution in the app and a render scale of 75 in MSFS (x0.75) which in terms of resulting rendered resolution should be more or less the same.

I took in-lens snapshots to compare the rendered image and monitored the CPU/GPU. I pinned the FPS to 38 to see how close the sim could get to that.

While it is a bit subjective, I struggled to tell the difference - same image quality and same CPU/GPU load and same FPS behaviour.

If I had to choose - Iā€™d say the base res plus 100 scale gave ever so slightly better clarity and the full res + downsclae was just that tiny bit smoother over all.

This says to me that it is an adavtantage to set to full res in-app and downscale in MSFS as that gives you more options to adjust the render scale in MSFS only without having to change the in-oculus-app settings which requires a oculus app restart.

That said, I am doing this with a 3080 ti - a lower spec GPU may mean a higher downscale from max for a smooth ride and that could well reveal bigger differences - thoughts/observations welcome on this!

I did try the other way - low render res and an MSFS upscale (>100) but this produced a poor image quality - this implies that it is not a simple product of the two settings but something more akin to super/under-sampling.

3 Likes

Where does ODT super sampling fit into this equation? And what about refresh rates? Since nobody gets above 40fps-ish, is there any reason to go higher than 72hz?

Most of the Oculus tuning guides I have seen avoid the ODT supersampling in favour of adjusting the Oculus render resolution (in the Oculus App) and Render Scale in MSFS VR settings - so seemingly it is similar to one or the other.

The Oculus Refresh Rate relates to the headset only - it does seem to mean that the headset has to work harder at higher rates but has no direct bearing on the FPS the PC CPU and GPU have to serve up.

Refresh Rate affects how comfortably you perceive the VR experience - some experience motion sickness at lower rates I believe

I find 90hz works well for me.

Sorry but the Q2 refresh rate you choose definitely effects GPU usage and hence overall performance. You can look at your win10 task manager GPU usage to confirm this. Try 120Hz and youā€™ll def see the difference, lol! I know that many think that with flight sims that cannot maintain full refresh rate fps that this should not matter, but it does imho.

With my Q2/rtx3090 (mainly using Air Link) Iā€™ve found the sweet spot for me is 80Hz and the res slider full right (native Q2 res) and Air Link dashboard setting at 200mbps dynamic. All my ODT settings at default/zeros except ASW disabled, Encoding width = 3664 (1:1 scaling), and link sharpening enabled.

I have never found ASW or frame limiting options to be very useful. Too many artifacts and I see very little difference in how smooth things look. I also do not see any advantages to adding super sampling (StreamVR visuals manual 100% and disable SS filtering btw) because once you have the Q2 res slider full right, link sharpening enabled, and encoding with at 3664 there are not any significant improvements after that. I think it looks fantastic!

Nvidia (currently using 496.76) control panel settings all default except the power option set to prefer max performance. Mucking around with these further does not improve PCVR performance imho. Iā€™m also on the latest win10 feature/security updates. No big win10 settings changes except the usual disable any usb power savings options.

Also, together with my VR Cover standard facial interface, their eyeglass spacer, their thin Cool pad, and Oculus Elite strap with battery Iā€™ve found my Q2 to be much more comfortable, with a larger fov, than stock. Of course Iā€™d like a larger FOV but I can easily live with this for now. I just need to move my heads around a little more, lol!

While some may be more refresh rate sensitive than others, I donā€™t seem to be. I cannot tell the difference between 80/90Hz but I do see minor improvements with faster racing sims compared to 72Hz. So, Iā€™ve settled on 80Hz for everything and this seems to work fine with all my games/sims, including fast action ones. The Rift S uses 80Hz and I did not have any problem with that as well. Nor did most users that I know.

I also have a good Link cable (VR Cover 5m Premium Link Cable) connected to my z390 mb usb3.1 gen2 type c port and this also works very well. I use the same settings but increase the ODT bitrate to 500mbps. This does improve the clarity of distant objects but Iā€™ve found that the freedom of wireless outweighs this, for me anyway.

The point Iā€™d like to make is that itā€™s important to get your base Q2 setting optimised before finetuning in-game settings. For those, youā€™re on your own, lol!

1 Like

So the solution then for mucking around with performance while in VR with this approach is tweaking the in game render scaling, since changing the headset resolution reboots the app? That was my reason for using SS beforeā€¦I could tweak to test without constant rebooting.

I think, like me, you will eventually find that using SS (or SteamVR % visual) is a very poor way to finetune things with a Q2. You are best to leave these at zero (and 100% SteamVR visuals) and hone into a good base refresh rate (I suggest 72/80Hz) and the res slider as far right as your PC system allows you to do. After that, finetune your in-game/sim settings. Otherwise youā€™ll just end up chasing your tail imho.

Thatā€™s what I have been doing - max res in the Oculus app graphics settings and then adjusting the render scaling in MSFS VR settings.

My only concern with this is whether having a non-100% render scale introduces more CPU/GPU load as the frames have to be up/down scaled - or that setting the oculus res at max meant that the GPU is doing work that is then thrown away by down scaling.

Does anyone know the relationship between Oculus resolution and render scale? I had assumed that resolution sets the frame size that the GPU renders and render scale then up/down scales the frame.

Anyone know if thereā€™s good benchmarking data out there on these various approaches to tweaking settings? I feel like getting a consistent VR experience in general is tough, and thus hard to control enough to benchmark accurately.

Also, anyone know if using higher res+render scaling controls should have no difference in sharpness compared to SS at lower resolution?

And lastly, with a 3080 and 5800x should I max my resolution? Or should I realistically be a few notches below max, or does it matter if I instead reduce my render scaling to compensate?

Been trying out full resolution @ 72hz, 100 render scaling, no SS. Definitely feels less sharp than SS and I have Link Sharpening enabled. Am I doing anything wrong here? I have my bitrate set to 0 instead of forced to 200ā€¦

Maybe try render scaling 90, bitrate 500, encoding res 3664.

Iā€™m at render scaling 100, encoding res 3664, and bitrate 200 (airlink). I also upped SS to 1.3 now and it is a bit sharper I think, without a sizable performance hit. Still not quite as crisp. Are there Nvidia settings I should monkey with to further increase that like Nvidia image scaling (sharpening), anisotropic filtering, or antialiasing?

Not really anything besides defaults with nvidia control panel except power option = prefer max performance. You can also try to change quality (below the power option) to performance (not high performance) and turn thread optimisation = off. Both of those may help.

Also, make sure Air Link bitrate is 200mbps dynamic (not fixed) and set curve distortion = Low (ODT). Also try turning off ASW.

Also, maybe try render scaling = 90 without any SS. If your Oculus desktop app device graphics settings are at 72Hz and the res slider full right, SS will probably not add much clarity, just lower your performance and cause stutters imho.

The latest nvidia 497.09 driver seems to work pretty well btw.

I have finally managed to get MSFS working again after update 7 and did some tests.

Comparing 72hz and 120hz with all other things being equal I did indeed see a bump in GPU (but not CPU) - however it was only a max of 6% extra GPU - and it varied between 0 & 6%.

I am still surprised to see even that, because the higher refresh rate is, at a simplistuc level, the re-displaying of a given frame many times to improve clarity.

So, if the GPU is producing 40 FPS and the headset set to 120hz, then each frame is diaplayed 3 times before the next new frame.

If the GPU only has to render any given frame once then why the extra load? The only thing I can think is that Oculus link is reading a given frame from the GPU as many times as needed to produce a 120hz stream, which would put a little extra load on the GPU.

Seems odd, though - youā€™d expect the headset display to handle the frame repetition, like TVs do.

As an aside, I have read that VR headsets implement high refresh rates through low latency - that is, to achieve the ā€˜black frame flickerā€™ effect, they display each frame for a very short time with no-light inbetween.

One dramatic thing I did notice was that low level flying at speed (600 knots, 1000ft or less) had a real wow factor at 120hz, where as at 72hz it was horrible. Donā€™t get me wrong - it wasnā€™t perfect at 120hz, but still impressive, albeit over open terrain rarther than cityscpaes.

11th Gen i9, 8 cores
64GB RAM
3080ti
Oculus Quest 2

1 Like

Iā€™ve been wondering the same. I also think it feels better at 120hz and thatā€™s what I use for my Q2 via virtual desktop.

There is definitely a larger image sent to the headset than what we can actually see (for example it is hard / impossible to see the dev mode window in my headset as it is so high). I am wondering if the headset does something clever with this excess bit of image, such that if you pivot your head left/right/up/down by a small amount, then the headset holds the image fixed in space and lets you see a bit of the excess image come into your view. And therefore when you are having small or just slow head rotations, you can get the movement responsiveness of 120fps when you are actually just seeing a c25fps image that has been moved very slightly at a speed of 1/120s. Disclaimer this is speculation and I am totally unqualified on these topics :joy: