FXAA/MSAA in VR compared

[Dave]

On 6/17/2020 at 4:20 AM, ACG_crane said:

VRSS is showing "Not supported for this aplication". Any clue why?

VRSS requires developer support - sort of - which is why it is defaulted off for all titles and then explicitly enabled title-by-title by Nvidia.

The reason is that it makes use of a title's built in support for variable rate shading - and forward rendering. It needs this support to increase the shading rate within a central region of the display to increase the degree of AA super-sampling within that region and to dynamically vary the size of the "fovea" region in response to GPU headroom changes. For those that have no idea what VRSS is - it is Variable Rate Super Sampling. You must enable MSAA for it to work at all. If you then set MSAA to say 4x on a VRSS supported title the driver will selectively  supersample the central region of the view at 4x. If MSAA is 8x then it will supersample at 8x. The radius of the supersampled region grows and shrinks in response to GPU headroom changes.

It is up to the developer to submit their title to Nvidia for whitelisting in the driver, but 1CGS have not - probably due to their use of deferred shading.

 

Quoting the Nvidia dev blog announcing VRSS back in January 2020:

Quote

VRSS can be applied to all VR games and applications that are DX11, Forward Rendered and have MSAA.  The VRSS functionality resides in the NVIDIA Driver.  The best part is that developers do not have to write any code to integrate VRSS, they just need to submit their VR game or application to NVIDIA for VRSS testing. NVIDIA will test the VR game or application, and if it benefits from VRSS, then it will be considered for whitelisting in the NVIDIA Driver.

 

It's interesting that the introduction of FXAA coincided with the change to deferred shading and that most people's complaints about the shimmering and aliasing began with 4.006. Because FXAA is a common workaround for the negative impact deferred shading has on antialiasing - it kinda breaks it. But deferred shading itself is a workaround for the exponential growth in GPU load caused by dynamic lighting - which is what delivers the post 4.006 lighting effects such as realistic aircraft skin reflections, canopy reflections and instrument glass. I suspect that FXAA was added rather than just as a "faster anti-aliasing method" (relative to existing MSAA performance) to some extent as a workaround for the impact deferred shading would have had on MSAA.

 

I like the new lighting made possible on current hardware by deferred shading but I'm personally frustrated by the fact that even on an overclocked RTX3090 I get a HMD full of jaggies that even 8x MSAA doesn't remove.

 

Quote

The main advantage of FXAA over conventional spatial anti-aliasing is that it does not require large amounts of computing power. It achieves this by smoothing undesirable jagged edges ("jaggies")^[4] as pixels, according to how they appear on-screen, rather than analyzing the 3D model itself, as in conventional spatial anti-aliasing.^[1] Since it is not based on the actual geometry, it will smooth not only edges between triangles, but also edges inside alpha-blended textures, or those resulting from pixel shader effects, which are immune to the effects of multisample anti-aliasing (MSAA).^[5]

The downsides are that high contrast texture maps are blurred; FXAA must be applied before rendering the HUD elements of a game lest it affect them too; and that polygonal details that are smaller than one pixel that would have been captured and rendered by MSAA and SSAA will not be captured and rendered by FXAA alone.

 

So FXAA can help with the texture aliasing that I think is the cause of the shimmering landscape but it does it by blurring everything kinda like a vaseline filter and definitely hurts spotting.

Edited January 3, 2021 by Dave

[Dutch2]

1 hour ago, Dave said:

 

SSAO is quite costly - it essentially uses a simplified ray-tracing algorithm to approximate global illumination (indirect bounce lighting from nearby surfaces) to improve the realism of shadowed regions which might otherwise look unnaturally dark and flat. In IL2 I personally think this adds almost nothing to the visuals in VR while costing precious FPS. Try turning this off and if you cant tell the difference you can enjoy the FPS boost without feeling like you are missing anything.

 

Not as been tested by @SCG_Fenris_Wolf  

 

[Dave]

49 minutes ago, Dutch2 said:

 

Not as been tested by @SCG_Fenris_Wolf  

 

Respectfully, I think Fenris' suggested settings are wrong. I am getting <9ms/frame with my Reverb on a 3090 with much better visuals than I did after trying Fenris' suggestions. Following his advice the image suffered and so did FPS.

Rather than just contradict though, I made a point of explaining why certain options are better or worse so people can consider the rationale and make informed choices. Good on Fenris for doing his own testing and sharing - I just don't agree with some of his results.

 

It is also worth noting that what works well for one hardware combination will not necessarily work well for another - so take any advice that isn't supported by explanation of the underlying features with a grain of salt.

Edited January 3, 2021 by Dave
The content rather than the writer

[Dave]

9 hours ago, Dutch2 said:

11 hours ago, Dave said:

 

SSAO is quite costly - it essentially uses a simplified ray-tracing algorithm to approximate global illumination (indirect bounce lighting from nearby surfaces) to improve the realism of shadowed regions which might otherwise look unnaturally dark and flat. In IL2 I personally think this adds almost nothing to the visuals in VR while costing precious FPS. Try turning this off and if you cant tell the difference you can enjoy the FPS boost without feeling like you are missing anything.

 

Not as been tested by @SCG_Fenris_Wolf  

I went back and edited that just now because the way I had written it didn't make clear the comparison was with no AO. My personal observation of this setting and the performance penalty stand. As our other settings differ quite a bit there is the chance enabling SSAO for him is interacting favourably with another option he has chosen which I have not.

For example, if the Ultra base profile enables ambient occlusion (which I can't know because the exact content of each of those profiles is completely undocumented) then adding SSAO on top of Ultra will improve performance. If the High base profile, which I use, does not provide AO then turning on SSAO combined with High will decrease performance. It would be helpful to know exactly what each of the base graphics profiles set - as it stands we are just using trial and error combined with assumptions. It is very common for GPU driver configuration to expose coarse grained settings (eg AA mode) which you then refine with finer grained settings (eg 2x, 4x, multi-frame interpolated). It is also common for pairs of options to work against one another (eg negative LOD bias with anisotropic filtering) so it would be extremely helpful to know what the starting state is before tweaking fine-grained options.

Edited January 4, 2021 by Dave

[FTC_Mephisto]

On 1/3/2021 at 7:20 PM, Dave said:

I am getting <9ms/frame with my Reverb on a 3090 with much better visuals than I did after trying Fenris' suggestions

 

Mind sharing your settings? I am also struggling with G2/3090 and surprised how low the performance is...

[III/JG52_Al-Azraq]

On 1/3/2021 at 6:04 PM, Dave said:

VRSS requires developer support - sort of - which is why it is defaulted off for all titles and then explicitly enabled title-by-title by Nvidia.

The reason is that it makes use of a title's built in support for variable rate shading - and forward rendering. It needs this support to increase the shading rate within a central region of the display to increase the degree of AA super-sampling within that region and to dynamically vary the size of the "fovea" region in response to GPU headroom changes. For those that have no idea what VRSS is - it is Variable Rate Super Sampling. You must enable MSAA for it to work at all. If you then set MSAA to say 4x on a VRSS supported title the driver will selectively  supersample the central region of the view at 4x. If MSAA is 8x then it will supersample at 8x. The radius of the supersampled region grows and shrinks in response to GPU headroom changes.

It is up to the developer to submit their title to Nvidia for whitelisting in the driver, but 1CGS have not - probably due to their use of deferred shading.

 

Quoting the Nvidia dev blog announcing VRSS back in January 2020:

 

It's interesting that the introduction of FXAA coincided with the change to deferred shading and that most people's complaints about the shimmering and aliasing began with 4.006. Because FXAA is a common workaround for the negative impact deferred shading has on antialiasing - it kinda breaks it. But deferred shading itself is a workaround for the exponential growth in GPU load caused by dynamic lighting - which is what delivers the post 4.006 lighting effects such as realistic aircraft skin reflections, canopy reflections and instrument glass. I suspect that FXAA was added rather than just as a "faster anti-aliasing method" (relative to existing MSAA performance) to some extent as a workaround for the impact deferred shading would have had on MSAA.

 

I like the new lighting made possible on current hardware by deferred shading but I'm personally frustrated by the fact that even on an overclocked RTX3090 I get a HMD full of jaggies that even 8x MSAA doesn't remove.

 

 

So FXAA can help with the texture aliasing that I think is the cause of the shimmering landscape but it does it by blurring everything kinda like a vaseline filter and definitely hurts spotting.

 

Great and detailed technical post.

 

That is exactly why FXAA was added: deferred rendering breaks MSAA (makes it look bad and destroys performance) and it is the exact same reason why games like Half Life Alyx use forward rendering. What we need is TAA or DLSS (which is kinda like TAA) so we can have a clear image with great performance again.

 

Until this is implemented, I'm afraid that disabling MSAA is the way to go as the huge performance impact that this option causes right now with deferred rendering while not removing the shimmering is just not worth it.

[Picchio]

Has anyone succeeded in applying SMAA through the newest version of Reshade, which is supposed to work in VR?

[Bvv_Fr_VR]

Hello,

i test my new GPU with Vive Pro 2 and i'm not sure between FXAA x4 et MSAA x2 (of course MSAA x4 is a lot more better but it's not my question ?) it's not a big deal if i can't make a difference, but it's not my question either ?

 

MSAA is generaly better than FXAA but less FPS. i made a lot of visual test ?, what do you think, which is the best between FXAA x4 et MSAA x2, i have allmost same fps but i'm not sure. maybe there is a little bit less AA with MSAA x2 but more blinking. maybe...

 

nb: i use ssao+sharpness+hdr, no questions about it for me.

Edited April 4, 2022 by BvvFr

[dburne]

1 hour ago, BvvFr said:

Hello,

i test my new GPU with Vive Pro 2 and i'm not sure between FXAA x4 et MSAA x2 (of course MSAA x4 is a lot more better but it's not my question ?) it's not a big deal if i can't make a difference, but it's not my question either ?

 

MSAA is generaly better than FXAA but less FPS. i made a lot of visual test ?, what do you think, which is the best between FXAA x4 et MSAA x2, i have allmost same fps but i'm not sure. maybe there is a little bit less AA with MSAA x2 but more blinking. maybe...

 

nb: i use ssao+sharpness+hdr, no questions about it for me.

 

I always preferred MSAA x2 , never cared much for FXAA.

[Drum]

After the last few game updates the need for outside game modifications (FSR/NIS) are no longer required for my system.  I'm using MSAA=2 because it does make things slightly better, but I'm also running WMR=100% & SteamVR=50% with HDR off (gamma=1) so have much more FPS to run all my settings at their top except Shadows=high & Clouds=high with a Base preset=Balanced.  Everything else is checked on, or at their highest settings and that's giving my system (non-OC) FPS=85+ steady now.

 

The most important thing IMO (which I don't see others experiencing, but they may not even realize, notice or have checked) is the Base presets higher then "Balanced" add blur/distortion to the mid & long range image which requires a higher SS setting to SS the crap out of the image, which in turn lowers the FPS and around in circles you end up going trying to get a better image you basically ruined by using a High or even worse, an Ultra Base preset.

 

They have made VR much better over the last few updates but IMO it's the Preset settings they now need to look into and fix as those are truly the root of all the blur I find.

 

Edited April 4, 2022 by Drum
Just to clarify, I use a G2 which is 2160p and the SteamVR=50% makes it 2184p. Zoom zoom baby!

[Drum]

Check the link below out, I went back to the Feb.22 driver version (511.79) and it's more clear indeed with zero FPS loss.

 

https://www.bing.com/videos/search?q=varjo+aero&qft=+filterui%3avideoage-lt43200&view=detail&mid=3B006F64482CEE6965643B006F64482CEE696564&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3F%26q%3Dvarjo%2Baero%26qft%3D%2Bfilterui%3Avideoage-lt43200%26FORM%3DVRFLTR

Edited April 4, 2022 by Drum

[Bvv_Fr_VR]

It's very close, it's pancake's screen, not VR!

 

With MSAA x2 in VR, i see small aliasing on the canon of the P51 for example, i have no this aliasing with FXAA x4, but on theses screens, i think MSAA is little better, it depends for what i think.

FXAA x4, there is less Aliasing a little bit. very close

13 hours ago, Drum said:

The most important thing IMO (which I don't see others experiencing, but they may not even realize, notice or have checked) is the Base presets higher then "Balanced" add blur/distortion to the mid & long range image which requires a higher SS setting to SS the crap out of the image, which in turn lowers the FPS and around in circles you end up going trying to get a better image you basically ruined by using a High or even worse, an Ultra Base preset.

 

They have made VR much better over the last few updates but IMO it's the Preset settings they now need to look into and fix as those are truly the root of all the blur I find.

 

 

i am in ultra base setting, and allmost everything maximum, i never test lower than ultra, i have to check what you say about it

But my game is very clean and sharp (no blur at all) SS 100% vive pro 2 2448x2448 per eyes

Edited April 5, 2022 by BvvFr