G2 (WMR) vs 4K (CPU MainThread anomaly) - What a difference!

User Support Hub Virtual Reality (VR)
1

Hi. I am lucky enough to have a G2 and a 4K monitor. Knowing from tuning the 4K settings that I can acheive a constant 60fps at 4K with a mix of medium and a few high and fewer ultra settings in dense areas, I did some quick math and the native resolution for the G2 is slightly more than 4K BUT close enough that if I can get 60FPS for 4K (8,294,400 pixels) then I should be able to get at least half of the native 90hz (45fps) for the G2 (9,331,200 pixels or 4.5K) because the G2 is only 12.5% more pixels than 4K.

So first thing to say is by fiddling with OXR and render resolution scale in MSFS, I kept the resultant resolution approx 4.5K but below 5K in VR at all times. I took off from Birmingham, UK airport and flew over Birmingham City centre at < 1000ft each test as it is Photgrammetry drawn and densely populated with buildings.

As many before me have stated and in simple terms, how many frames per second are delivered is derived from how fast the CPU can determine where every object is in relation to the the view point (Main Thread) and then how fast the GPU can receive that information and render that information to the display.

Long story - of endless tweaking sessions, loss of hair and learning a new language that I can’t speak in front of anybody I respect - cut short, I noticed that the 60-80fps I got in 4K did not translate at all with very similar settings to VR.

I have a 10900k, 3090 Ultra at stock and 32GB RAM DDR@3800Mhz, M.2 drive for OS and Fast SSD for MSFS so I was suprised to see how the frame times differed between 4K and VR.

In both VR and 4K I am seeing about 9-13ms frametime on the GPU
In 4K I am seeing 5-8ms frametime on the CPU (MainThread)
In VR I am seeing 19-28ms frametime in CPU (MainThread)

This I consider this to be an anomaly, I seem to be limited by my CPU.

I understand that each scene (left/right eye) has to be calculated for Stereo 3D but as each viewport is 5/8 the size of 4K would expect that the CPU calculations would only take (5/8 x 2) 25% longer, not over 3x longer.

Anyhoo, I have settled on Medium settings mostly for VR with rendering at 100 SS and TAA in MSFS and 50% in OXR to get about 4.7K overall resolution with super fluid motion, but will probably settle somewhere around 80/80 if I can get the same fluidity to get better clarity at distance and compromise on the guages, until such a time that Asobo work out that they don’t need to calculate the whole scene in 4.5K twice (which is a feasible assumption IMHO)

Happy to be humbled, but feel this may help others in some little way without having to spend 4 months fiddling to acheive what is impossible when assuming that 4.5K VR is similar to 4K pancake.

2 Likes
2

From my Oculus VR experience when comparing a FullHD monitor and Oculus Rift CV1, the amount of power needed to compute a VR frame (both eyes) is more between 2,5 and 3 times (nearest to 3 times) versus what is needed for the fullhd monitor, due to the management of 3D headset position and rotation in space all axes (gyroscopes and positional tracking) , stereo computing with higher fov for each eye than final picture (due to edge deformation).

E.g. for a ratio of 1:1 (render scale 100 and no supersampling) MSFS compute 1344x1600 per eyes, and my headset is 2 screens of 1080x1200. That added to all the VR management needed, could explain a little what you experiment IMHO (on mainthread side).

For a given apps, if I can reach more than 240fps on my fullhd monitor I’m mainly good for VR at 90fps (with some settings tuned obviously).

3

@MrPix2020 Would I be correct in assuming that you’re flying GA? How does it translate to the A320? I’m still struggling to comprehend why Medium settings are pushing the limits of modern hardware - everything I’ve tried ends up with a blurry, studdery soup.

4

Yes, what you are experiencing (even with your high end hardware) is what many others have also seen…VR is much harder on the CPU and GPU than 2D even for the same # pixels. I have a nearly identical hardware setup to the OP and have had to dial my VR settings back to Medium/some High and 80% render scale from all Ultra/High in 2D at 100%, and even with that the FPS drops nearly in half from nearly 60 to ~30. It’s just a reality of the VR demands and also true that MSFS is not optimized at all for VR, it just came out last December or so and Asobo has said it isn’t optimized. If you read up on other games in VR the same thing happens where 2D FPS is way higher. I have mine tuned to hit 30 fps with the highest graphics I can for that 30 fps and then have motion reprojection turned on to get that up to 60 (I have my G2 set to 60hz as opposed to 90hz) as I like that fluidity although it can have blurs that some folks find distracting. I tried the 90hz setting on the G2 and the hardware/software just isn’t optimized or capable of producing the frames and I noticed the extra frames being interpolated and it looked stuttery to me (some don’t see it as much, it seems very personal to what tradeoffs one wants to make). Also, if’s also harder in VR to render the glass cockpit planes and even with the cockpit display setting turned down I can see more FPS hit in those planes as opposed to GA aircraft.

Having said all of that, I still almost exclusively use VR for the immersion and experience overall and will stick with it rather than go back to 2D despite 2D having better clarity at full 4k with higher end equipment. As of now, I have it all set to 1440p and am happy with the tradeoffs of FPS and graphics settings and smoothness…but I’ve spend countless hours tinkering to see what I like best.

1 Like
5

Just the Spitfire from Flyingiron and the Cessna with analogue guages tested, I don’t fly anything that can take too many passengers, they’d all be dead with my landing abilities (I’m suprised the British Museum has not been on to me about the demise of so many MK IXs at Coventry and East Midlands!

6

G2 is about 6K in resolution when you factor in the upscaling required to deal with lens distortion near the edge. On top of that, G2 uses about 25% of your GPU power just to have the WMR active as an environment for VR. You can test this by running any GPU benchmark with G2 connected. Even when you are not rendering any game, your score will drop by about 25%. It can also be validated by the power draw on your GPU.

Expect about 30% performance drop in G2 compared to 4K. The variance could be greater depending on the graphics settings you use.

7

30% drop…?? the VR performance was < 30% of 4K pancake without the extra render resolution that you mention (yes I know all about that), that’s what got me thinking this wasn’t right. Re-read what I wrote in the OP, the res was always limited to around 4.5K not breaching 5K, I controlled that with OXR/MSFS SS. So what you have written may be true for other games/sims (and indeed correlates with my experience in iRacing for example), but my testing proved that this is not the case in MSFS… there is something wrong for it to tax the CPU like it does. between 3x to 4x CPU MainThread timing in VR compared to 4K pancake (oh and I forgot to mention another anomaly, the CPU utilisation whilst in VR is actually 50% of the CPU utilisation in 4K - work that one out!) You talk about GPU in your post, but largely this remains great with almost equal frametimes on VR and 4K pancake. This I would wager is NOT GPU related at all, but some poor general code optimisation prior to the render calls either in WMR, holographic drivers or heaven forbid, MSFS 2020 itself.

BTW, I am not new to VR, I started with the kickstarter project for Oculus (a.k.a. DK1) then was sent a DK2, had a CV1 from before it was launched, Vive Index, Rift S and now the G2… WMR is the first time I have experienced such a drain on the CPU with any of my setups (usually top of the range kit) in the past 8 years! It’s normally the GPU that is trying to keep up.

With the Rift S (sold last week to pay towards a second G2 for a mate) the CPU did a far better job of keeping up with the GPU (it’s not that way around but you get the comment!)

1 Like
8

I might be completely on my own here but… the frame-rate difference doesn’t really bother me that much on the G2 and I am just so glad that this technology exists to give me the experience that it does. Running a 3090 on a i9 with 32GB, I never use MFSF without VR anymore, I could never go back to using a monitor. Using anything other than VR just seems like a video-game to me now after fully adapting to the immersive feeling of actually being there. Its night and day different.

That said, I tend to fly in Australia or NZ where the scenery isn’t as intense as it is in Europe or the US but still hugely impressive.

I can only imagine what VR is going to be like in 4-5 years time when compute power and MSFS development catches up.

1 Like
9

It’s clear MSFS is not optimized for VR…it just launched last December and many forum members have spent countless hours adjusting settings in WMR, MSFS, OpenXR, in a huge chase for playable experience even on high end hardware. It doesn’t help that NVidia drivers appear to be problematic for MSFS (one of the NVidia employees actually asked for MSFS users to send in their testing using an NVidia protocol and software to help try and sort out MSFS related bugs (his words not mine). Asobo hasn’t said anything in their releases so far about meaningful progress on VR other than it’s “ongoing”. So, I hope we see some significant MSFS optimization that helps VR for users with all hardware types. For my i9, 3090, 64gb setup its playable in VR but at 1440p (90% render too) and only hits 30 FPS (reprojection to 60) at high/medium settings, but in 2D I can run full 4K at Ultra/High and hit 45-60FPS …so quite a large drop from 2D to get VR to smooth and playable (and it’s cpu limited in VR much sooner than in 2D for me). I really look forward to any software optimization they might develop in the future. I’m not a hardware/software developer but it does appear that MSFS is a hog on CPU in 2D and even more so on 3D (even with things like multiplayer and live traffic off…I can’t run with those on unless I lower settings even more)

10

I don’t care if it were 8K…2d pancake just doesn’t hold my attention.
I’ve tried MSFS about 11 times in 2D before VR released and could only stay in flight 10 minutes before I grew bored at the image. I shelved the sim until VR released.
I can no longer enjoy 2d pc gaming, but I’ve been spoiled and ruined by stereoscopic 3d since 2012 with Nvidia 3D Vision. Jumped on VR in 2015 with the DK2 and never looked back.
As for performance its always been a dilemma with 3D/VR being bottlenecked by single core performance and no SLI(pretty much useless in 2d also) support by design. The 3D Vision performance tax was far heavier on GPU and CPU than VR. Back then you could pretty much count on losing â– â– â– â–  near half your FPS with stereoscopic 3D on.
BTW since Nvidia decided to axe 3D Vision and completely wipe all remnants of the software out of later drivers I’m now stuck with this 1440p PG278QR “now 2d pancake only” monitor.:cry:
From what I hear folks have still managed to run 3D Vision on later Windows 10 updates and even GeForce Drivers through very tedious hacks. Luckily for me all of the titles I enjoy now either have native VR or an injection app that works for them.

11

This. I don’t care what FPS I get in VR as long as it’s smooth there’s zero chance that I am able to go back to 2D. VR even at the low end graphics still massively beats out 2D flying. The immersion is so close to real life that the graphics downgrade is a non-issue. I’ll remain hopeful and patient that hardware improvements and software optimization will one day get us MSFS in Ultra graphics in VR, but in 2021, it’s not possible with any hardware with the G2.

2 Likes
12

Aahhh the language of VR. I love it!

13

VR is amazing and the native stereoscopic 3D makes even outdated textures in games & sims look great and pop out at you with convergence. Its the absolute only way I could still enjoy FSX in 2021.
Just something about that feeling of depth and convergence when flying over all those 3d object autogen buildings on an approach and seeing little 3D cars on the freeway.:beers:

14

You should put “VR” in the topic title.

Thanks…

15

It’s in the VR section @MSFSRonS so no need. The anomaly I describe is to do specifically with the G2 and WMR and MSFS2020, I don’t get the same results with Oculus, so broadly titling VR would be misleading.

I have however retitled appropriately so others like you get the right idea of what the thread is about straightaway without having to read the first post.!

16

Try to reduce render resolution and supersampling in VR so that the VR frametime matches your 4k resolution frametime.

If there really is a serious anomaly then the difference in resolution should be quite noticeable.

17

I too have spent 4 months pulling my hair out over a few assumptions, this one being one of them. I have also noticed that VR takes 2-3x the amount of CPU that non-VR does. This probably shouldn’t be the case and I hope it gets sorted in the ongoing performance enhancements.

2 Likes
18

Thank you.

G2, Oculus, WMR ? No idea what that is.

19

There’s a bug somewhere between MSFS, WMR, and the NVidia driver.

If you can’t do 45 frames, then it enables V-sync (regardless of settings), and tries for 30. It’s supposed to reproject 2 more frames (to get to 90 FPS), but it fails and drops a the second frame.

If you can do 45, then it will lock to that and repro one frame, which works great. The problem is that not even a top system can do 45 on high settings (100/100, high/ultra) in VR.

If they can fix the +2 reprojection with 30 in game, then it will be great.

When my system is locked to 30 (trying for 2 repro frames), the CPU (the one core) and the GPU are not very loaded.

So turn down to get 45 at 90 or higher settings to get 30, with 60 Hz. Either way, as long as you’re only reprojecting one frame, It’ll be good.

NVidia has acknowledged that there’s a bug with VR with this one game, and they’re trying to find it for newer drivers. 457.30 until then.

20

then you probably don’t need to :wink:

Fly high and safe buddy!