Stutter/judder/ghosting without frametime increase or framerate drop (likely not just in VR)

[savagebeest]

This issue isn’t ever going to be addressed as it’s seems. Hopefully clod vr will not have this issue. 

[horendus]

The problem does go away with increased CPU performance through brute force. I know longer consider it a problem for me on a 13700k and I expect in another generation or 2 it wont even be reproducible if tried.

 

I guess the AI and rendering functions are so intertwined that they cannot be separated without enormous effort from the programming department who are probably hard at work on the next instalment. 
 

However I do hold onto some hope that some wiz bang programmer is hired by the studio and solves the problem to try and impress their boss.

[YoYo]

On 5/22/2022 at 8:36 PM, firdimigdi said:

The issue

Singleplayer missions (career, AQMB, scripted campaigns - generally missions with adequate AI activity [nothing extreme]) are juddery despite frametimes being low and the framerate being locked to the maximum for the HMD (I have tried both 60 / 90fps on a G2 and 80fps on a Rift S). This is something that has started in some update near January 2022. It is only visible in the HMD, the desktop mirror does not exhibit this.

 

Recording a track while this is occurring and playing it back results in a completely smooth playback. It is also detectable if you decelerate time in mission but somewhat less so if you accelerate time in mission.

 

What does it look like

It's as if the rendered frames are reaching the HMD slightly out of sequence - this happens for both eyes, so it's not an inconsistency between left and right.

 

Easiest missions to see it in

Fortress over the Volga, 1st mission

Burning Steppe, 3rd mission

Or the missions I've attached in this post

 

Roll left right and keep your eye on the horizon out of the side of the canopy and it will become very obvious; alternatively get close to a plane and barrel roll around it while keeping it in view.

 

The hardware this was tested on

5900X/32gb 3600Mhz/RTX 3080Ti

i9 9900K/32gb 3600Mhz/RTX 2080

Reverb G2

Oculus Rift S

 

The software tried

 

All machines are running Windows 10, latest nVidia drivers - tried also rolling back to the 496.xx generation for testing's sake.

 

• Native unadulterated SteamVR.

SteamVR chart from the G2 while the game is juddering

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And from the Rift S

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As is clear from both charts there are no dropped frames, no synthetic frames and it operates well within the threshold for a maxxed out and stable framerate.

 

• OpenComposite (OpenXR branch for the G2 and the original for Rift S) - this yields even better/smoother frametimes, yet the issue is still very much present.

 

I tried running the lowest of the low settings. I tried a completely clean install of IL-2 despite there not being any mods installed when testing. The judder always occurs as long as there are enough AI planes/vehicles to induce it.

 

Also, I swapped the HMDs between both PCs and got the same result.

 

What it is not

- Motion smoothing/reprojection, I kept it disabled.

- A discrepancy between left and right eye rendering, it is still perceived with either eye closed.

- Game settings dependent, it happens even with the lowest graphics settings and at 50% the HMD's render resolution.

- In-game weather related, it can happen with clear cloudless skies.

- Map-related, can happen on any map.

- Distance related, as long as the AIs are spawned they will have an effect.

- Framerate drop, the frames remain at max.

- CPU overload, CPU usage remains somewhere under 50% at all times.

- Thermal throttling, both PCs have liquid cooled CPU and GPU and never reach their thermal limit.

- Dependent on CPU architecture, occurs both on Intel and AMD.

- Dependent on HMD ecosystem, happens just the same with Oculus as with a WMR headset.

 

After several rounds of testing:

It's the presence of AI-controlled airplanes that is causing this the most, even if they are not active/flying and just parked.

Below is a set of two MP dogfight missions: in one there are 33 ground vehicles moving along a road and it does not exhibit ghosting/stuttering, in the other there are 18 planes just parked on a runway and the issue is triggered.

 

stuttertest - two missions vehicles vs planes.zip 24.97 kB · 9 downloads

 

And yet another MP dogfight mission making it even easier to test:

 

stuttertest - plane spawner on flare.zip 9.21 kB · 5 downloads

 

Shoot a flare and a FW190 will spawn and start circling - doing it this way I saw that it actually starts much earlier than I thought it would, I started noticing micro-stutter at about 10 spawned planes when playing this mission locally.

 

If you play the above mission in multiplayer, hosted on another PC, they will be smooth.

 

Other posts mentioning this issue

 

And some more commentary here:

Original post:

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I've been trying to figure out an issue I keep seeing in SP scenarios, or Dogfight missions in a server hosted in-game with multiple AIs and especially with ground units. This is most easily perceived in VR (note: there is no motion reprojection/smoothing involved).

 

Steps to reproduce easily:

1. use the Easy Mission Generator to make a Dogfight ground attack vs vehicles mission (it doesn't have to necessarily be such a mission as the generator will add ground units usually on the map anyhow, but it's easier this way) - alternatively AQMB can be used but there's extra steps to get the _gen mission modified to use in step 4

2. start a server in the game and load this mission

3. observe that when there are multiple ground unit AIs active that while the frametimes remain low and framerate remains high there is a very obvious reduction in the fluidity of motion - no dropped frames or even synthetic frames are shown in SteamVR/fpsVR's performance overlay

3b. easiest way to notice is if you are in a plane with high roll rate and flying over a road - keep your eyes on the road and do quick rolls left-right, observe how the road can appear slightly ghosted

4. host the exact same mission on another computer (dserver) and everything runs perfectly smooth

 

Note: you do not need to be near the AI for it to occur as long as they're spawned and active somewhere on the map

 

I can also provide much simpler missions than those generated by the Easy Mission Generator which reproduce the exact same result as above and it is also something that occurs with AQMB missions, career missions and scripted campaign missions.

 

One can rush to say "yes, ok, it is taxing your computer less since you are running it on another PC" but this should surely manifest itself in the framerate actually going down and there being excessive CPU/GPU usage, which is not the case, the framerate indicator in game remains locked at 90fps (as it does in any external monitoring utility) and the frametimes remain way below 11ms which is the threshold for maintaining 90fps.

 

The hardware involved is a 5900X/32gb 3600Mhz/RTX 3080Ti - the secondary machine used with dserver to test step (4) uses a "lowly" AMD 3700U.

 

I guess it's worth mentioning that weather conditions or reducing graphics settings have no bearing on this - it is always there as long as AI ground units are involved.

 

I noticed the same issue! Max FPS but sometimes I see „jitters” on objects. Looks like game issue.

[YoYo]

After almost a year, I returned to IL-2 (VR, RTX 4090, i9 13900K, no any motion reprojection, 72Hz=72FPS) and for 2 weeks I have been wondering what is happening. In fact, I have to confirm that there is a problem with performance but in objects. Despite the constant, maximum frame rate, I can see something that I would call "jitter" on passing objects, especially (e.g. planes but not only). This is a completely strange situation, because as I write. FPS are very good. However, objects can sometimes shake (especially during dogfights). I will add that I also have other simulators and all of them are OK (including DCS). I have been testing various options for 2 weeks. I thought it was a problem with my settings. However, this shaking always appears (it is most visible in Career mode - I confirm). I finally came across this and other threads and as you can see, people have been complaining about this topic for over a year. I have exactly the same thing. Currently the IL-2 BoX has some jittery problem and it is not related to FPS.

 

Btw. I would like to add that I also see this jittery sometimes on the ground, the feeling in the cockpit I have super smooth picture, but when you look at the ground you can also see it, maximum frames (no drops too), the settings of VR or in IL-2 have nothing to do with it.

 

So the Team? Can you check it and do the fix for this issue, this is quite a serious problem.

 

Perhaps the next version of IL-2 (Korea?) should support multithreading, I think this is missing especially at the moment. However, I would also like to add that I have never had a problem with IL-2 before and everything has always worked fine (in IL-2 CloD is ok still too). Now there is a problem, any chances to solve it?

 

@Han @Regingrave

@-DED-Rapidus

Edited January 10, 2024 by YoYo

[YoYo]

Interestingly, when I talked to a friend Today, he said he had the same problem with "jittery". He is using Quest 3 but from what I saw in this topic and the others, this applies to all goggles.

[womoWoMo]

I guess I'll just add my moaning to the chorus.  I've been loving the single player campaigns.  I got a Quest 3 largely because I thought this game would be awesome in VR, but the stutter is so distracting it's actually less immersive than just playing flat screen.  I've tried everything I could think of.  I messed with e cores and core parking (helped a similar issue with elden ring) and changed just about every graphics setting I could find at every level.  Nothing seems to make it go away.  I could be getting 120 fps with 30% or 40% max reported CPU usage, but the ground still looks like its struggling to catch up.  The really killer part is that the most exciting moments are when it's the worst.  Seems like we've lost hope for resolving the issue, but if anyone has any ideas let me know. 

 

PC for what it's worth:

i7 12700

32gb ddr5

AMD RX 7900XT

Quest 3 - Virtual Desktop

[kissTheSky]

5 hours ago, womoWoMo said:

I guess I'll just add my moaning to the chorus.  I've been loving the single player campaigns.  I got a Quest 3 largely because I thought this game would be awesome in VR, but the stutter is so distracting it's actually less immersive than just playing flat screen.  I've tried everything I could think of.  I messed with e cores and core parking (helped a similar issue with elden ring) and changed just about every graphics setting I could find at every level.  Nothing seems to make it go away.  I could be getting 120 fps with 30% or 40% max reported CPU usage, but the ground still looks like its struggling to catch up.  The really killer part is that the most exciting moments are when it's the worst.  Seems like we've lost hope for resolving the issue, but if anyone has any ideas let me know. 

 

PC for what it's worth:

i7 12700

32gb ddr5

AMD RX 7900XT

Quest 3 - Virtual Desktop

Unfortunately your situation might be exacerbated by the AMD video card. In the past, VR performance was definitely worse on AMD GPUs all else being equal, but I don’t know for sure how much they’ve improved things thru firmware and driver updates.

[womoWoMo]

48 minutes ago, kissTheSky said:

Unfortunately your situation might be exacerbated by the AMD video card. In the past, VR performance was definitely worse on AMD GPUs all else being equal, but I don’t know for sure how much they’ve improved things thru firmware and driver updates.

Yeah, I remember when I got it the big knock on it was it was garbage for VR.  At some point they released a major driver update that apparently resolved the most fundamental problems it was having with VR.  This was all before I got a VR setup, so I just heard about it all second hand.  As of now it generally works pretty well for the VR applications I've tried.  It's not the 4090 obviously, but it puts out good frames.  Even in IL-2 nothing is reporting a GPU bottleneck and the frame times are good, it's just this weird stutter effect with landscape and object in single player like other people are describing.  It seems to not really be affected by the graphics settings and only happens when there are AI planes around.  It's a bummer because I was really looking forward to working through the missions in VR, but it's pretty unpleasant.

[354thFG_Drewm3i-VR]

Happens for me too. Sorry to keep tagging ya @LukeFF, but this needs to be looked at by the team. VR performance has been getting incrementally worse for years now. I also run a beastly system with a Quest 3 and lock out frames but have the stutter/tearing when looking to the side at the landscape.

 

I suggested they implement the VR Performance Toolkit by @RavenSystem as a minimum since it helps some, but doesn't work online: https://duckduckgo.com/?q=il2+vr+performance+toolkit&ia=web

Edited May 1, 2024 by =DW=_Drewm3i-VR

[kissTheSky]

46 minutes ago, womoWoMo said:

Yeah, I remember when I got it the big knock on it was it was garbage for VR.  At some point they released a major driver update that apparently resolved the most fundamental problems it was having with VR.  This was all before I got a VR setup, so I just heard about it all second hand.  As of now it generally works pretty well for the VR applications I've tried.  It's not the 4090 obviously, but it puts out good frames.  Even in IL-2 nothing is reporting a GPU bottleneck and the frame times are good, it's just this weird stutter effect with landscape and object in single player like other people are describing.  It seems to not really be affected by the graphics settings and only happens when there are AI planes around.  It's a bummer because I was really looking forward to working through the missions in VR, but it's pretty unpleasant.

So good to hear AMD had sorted their issues. Good to have alternative(s) to team green. 

[dgiatr]

1 hour ago, =DW=_Drewm3i-VR said:

I also run a beastly system with a Quest 3 and lock out frames but have the stutter/tearing when looking to the side at the landscape.

 

I

What's the cpu of your system?

I think the faster the cpu the less frequent is the stuttering issue to happen...

[kissTheSky]

7 hours ago, dgiatr said:

What's the cpu of your system?

I think the faster the cpu the less frequent is the stuttering issue to happen...

Yes, as someone else wrote earlier, brute force helps. I’m on 13900KF and 4090, still have stuttering in Bodenplatte career bomber escort missions. Slightly less than when I used to have 12700KF and 3090, but not by much. 

[firdimigdi]

This specific stutter (where you notice the landscape stutter when rolling) seems to be due to a delayed position update of the player cameras when they are attached to the airplane in cockpit view. If you use an external camera you won't witness this stutter - the enemy planes, etc will still appear to stutter but at least your own view will be stable. Similarly, as I wrote previously, the stutter is nowhere to be seen when viewing a replay.

 

IMO, while not a proper fix (as that is likely impossible with the current game engine), if at least the cockpit cameras positional update function could be moved out of the part of the loop that is being blocked, or if some sort of position averaging function was applied to it, then at least a big part of the perceived stutter will go away since the landscape will stop stuttering as bad.

 

Edited May 2, 2024 by firdimigdi

[354thFG_Drewm3i-VR]

On 5/1/2024 at 9:47 PM, dgiatr said:

What's the cpu of your system?

I think the faster the cpu the less frequent is the stuttering issue to happen...

An i9-13950H and RTX 4090 with DDR5. It's not my cpu. It was also about the same on my less powerful 5800X3D RTX 3080 desktop.

[savagebeest]

How does one “brute force” the CPU? Does this mean overclocking? I have a 12700kf so I don’t think it’s possible to OC this CPU. 

[womoWoMo]

23 hours ago, savagebeest said:

How does one “brute force” the CPU? Does this mean overclocking? I have a 12700kf so I don’t think it’s possible to OC this CPU. 

I think they just mean compensate for the unoptimized software with overpowered hardware.  For example there is no reason in the world that you should need a 13900 to run this if the software was designed to account for this issue, but since the software is what it is the extra hardware power helps (although apparently doesn't eliminate the issue).  I have a 12700 too, which honestly should be overkill for this application, but since it's not designed to take advantage of modern CPU architecture efficiently, here we are.

[savagebeest]

Yeah makes a lot of sense. What a shame. Inside the cockpit the weather is beautiful but outside things are jittery. Oh well. 

[kissTheSky]

8 hours ago, womoWoMo said:

I think they just mean compensate for the unoptimized software with overpowered hardware.  For example there is no reason in the world that you should need a 13900 to run this if the software was designed to account for this issue, but since the software is what it is the extra hardware power helps (although apparently doesn't eliminate the issue).  I have a 12700 too, which honestly should be overkill for this application, but since it's not designed to take advantage of modern CPU architecture efficiently, here we are.

That’s exactly what I meant.  Couldn’t have said better.  

[SCG_motoadve]

Returned to IL2 after more than a year or so, 4090, AMD 7800X 3D, 64GB RAM.

Settings are Ultra, no HDR, no SSAO, no sharpen.

Looks real nice and maintains 90FPS , but even at 90FPS I get jittering, stuttering when objects move in front of my plane or to the sides, tested in career, and single player missions.

Kind of ruins immersion.

[Angry_Russian]

 

On 5/25/2024 at 3:54 PM, SCG_motoadve said:

Returned to IL2 after more than a year or so, 4090, AMD 7800X 3D, 64GB RAM.

Settings are Ultra, no HDR, no SSAO, no sharpen.

Looks real nice and maintains 90FPS , but even at 90FPS I get jittering, stuttering when objects move in front of my plane or to the sides, tested in career, and single player missions.

Kind of ruins immersion.

Got myself 7800X3D and was curious whether they fixed this. Now thanks to you I don't need to bother checking.

 

Apparently 2 years is not long enough for this to be addressed and fixed. Having judder just because of the head camera shake is just ridiculous, literally no other game has that, why positioning can't be filtered/smoothened? I'd be glad to have 2-3 frames head camera delay instead of this crazy stutter. Haven't played the game since the clouds update because of this - this was when this problem started for me, but I see reports earlier and later than that. Really regret purchasing the content for IL-2, as all I can do in VR is just small 4x4 fights and MP, which I'm not interested in. Not going to buy the Korea either, unless this is solved.