Sgss anti aliasing without the massive fps hit!

As most of us know, the only thing that gets rid of AC's awful shadow flickering and texture crawl appears to be Nvidia's Sparse Grid Transparency Supersampling (SGSS). It can make AC look gorgeous, but it's incredibly resource intensive at higher levels. If you have Nvidia Inspector, there is a way to set up your AA that gives you the benefits of SGSS at easily half the FPS hit. I'll explain it here, and put a TL/DR at the end if you just want the settings without reading the novel

Note that you need 1) an Nvidia GPU, and 2) Nvidia Inspector.

First, a few known things about SGSS as it relates to AC.
Disclaimer: I don't claim to be a tech genius by any stretch, this is all just what I've discovered through research.

Using Nvidia Inspector, SGSS is basically an additional layer of AA running alongside "regular" AA (in this case, AC's AA options of 2x, 4x or forced 8x). SGSS needs regular AA in order to work correctly, AND must match its setting (2x, 4x, etc.) because SGSS gets its sample coordinates and grid pattern from regular AA samples. This is apparent if you try a mismatch of, for example, 4x AC AA and 2x SGSS; it will actually be of lower quality than both settings being at 2x. This presents a few options/problems:

- you could match 4x AC AA + 4x SGSS (or 8x + 8x if you force AC AA to 8x). 4x SGSS gets rid of very nearly all of the flickering shadows and pixel crawl and looks great, but utterly destroys your FPS.
- you could match 2x AC AA + 2x SGSS. 2x SGSS gets rid of almost the same amount of the flickering shadows and pixel crawl as 4x SGSS, and you get to keep a ton of FPS, but everything looks crap at only 2x AA.
- you could mismatch 4x AC AA + 2x SGSS to try to save some FPS while getting better AA, but it will not fix shadow flickering/pixel crawl, and still look like crap because of the AA/SGSS mismatch.

Part of the solution: Coverage Sampling AA (CSAA). It increases the number of AA coverage samples, increasing the accuracy of the AA with minimal performance hit. CSAA also works well with SGSS, because it's not a different form of AA, it's the same AA with the same coordinates/grid pattern that SGSS works from, just increased. So now we have the best of both worlds: we can match AA+SGSS at 2x to save resources, then add CSAA to increase the AA effect of 2x AC AA. Still with me?

Another known problem with SGSS is that it tends to blur the image. There's a few easy solutions for this that most of us already know, but I'll explain it in the settings...

TL/DR:
Nvidia Inspector settings:


A few things to note...
8x CSAA is the sweet spot, 16x doesn't look much better and it's a resource hog.
Enabling Transparency Multisampling as well as SGSS adds another layer of shadow-smoothing AA.
Nvidia FXAA is much higher quality than AC FXAA, so enable it on Inspector to really smooth out the rough edges. Yes, it blurs, but we'll sharpen it later.

AC settings:
Open your assettocorsa/system/cfg folder, and open Graphics.ini.
Make MIP_LOD_BIAS=-0.5 (sharpens the image nicely without too much LOD flickering)

In-game, set:
Aniso Filter = 16x
Anti Aliasing = 2x
I also suggest putting Shadows to Ultra for best shadow viewing enjoyment

Everyone will get a slightly different result using slightly different rigs, of course. I sacrificed PP Filters for more frame rate when using 4x SGSS, and FPS floated around 60-100. I can now use PP Filters and Ultra shadows, AC looks brilliant, and I still average 120+ FPS!

EDIT: After playing a bit more with LOD bias, and giving FXAA a re-look, I have to agree FXAA still blurs too much, thanks Tommi! Turned FXAA off and changed LOD bias to 0.30... MUCH better, everything is crisp and not too aliasy (with a few exceptions like some wires and distant signs on the tracks).

 

As an SGSS junkie I'm quite excited by this. As you say 4x SGSS looks awesome but really hammers fps.

When I get some spare time I'll give this a go.

 

dammit nvidia gets all the fancy stuff. Ive been messing around with MLAA trying to get that to work but it keeps messing up the DOF

 

Only if AC would accept SGSS (SuperSampling) from AMD gpu driver. I use it with dx9 sim racing games and looks very good.

 

8x CSAA deffinetly recommended. I don't like FXAA so I leave it alone.
With medium settings ingame I keep steady 60fps (locked) @ 5760x1080 and with 24 AI grid even in the fps heavy Monza and Nordschleife it doesn't go under 50fps at any moment.

CSAA gave my ACorsa the last fine graphical touch I was missing even without knowing it.

 

Thanks, seems to be some improvement from my settings in sig. Though similar to what Tommi ways, FXAA appears to blur a bit too much despite the negative LOD bias, but perhaps it might also be my monitor that sort of appears to have some matte finish. I also don't seem to notice much difference between AF=8x and 16x.

 

Biggest problem using LOD bias (which can eat fps itself if going to negative) or SweetFX to sharpen FXAA blur, is to merely remove the benefits its giving in the first place.
Blur goes away when sharpening enough, but also the pixels comes back.

I leave the AF at 8x and ingame AA 2x. Biggest fps hit/least benefit is between 8 -> 16x AF, and ingame AA is quite heavy with high res (as most AA is @ 5760x1080).

edit: How I recommend always to do this kind of graphic settings dance in racing sims.
Lower the graphics settings to the point that you get big fps, 120+ if that is possible.
Then drive, get the feeling for it, and then start increasing effects, AA, etc... to the point where you are happy with the graphics and you are still have atleast steady 60fps when hotlapping.
If the game play suffers at 60fps, there is few explanations for it which I'm not going into atm., but this way you can make educated decisions, knowing how good the game can actually feel.

 

SSAA works well with AMD too. But you can't do it with a profile to make it works with AC. You need to set it directly in the System Settings.

So in the AMD CCC => Gaming => 3D App Settings => System Settings (SSAA doesn't work with any app settings for AC) => AA method => Super Sampling. Let everything else by default.

Then in AC select 2x or 4x AA and you'll have 2x SSAA or 4x SSAA.

2x SSAA works well in my case with my HD 7790.

 

After playing a bit more with LOD bias, and giving FXAA a re-look, I have to agree FXAA still blurs too much. Turned FXAA off and changed LOD bias to 0.30... MUCH better, everything is crisp and not too aliasy (with a few exceptions like some wires and distant signs on the tracks). I went back to no PP Filter though, to gain back all the FPS. After you see AC running at 144+ FPS, you can never go back to 60 FPS

 

Easy with a 144Hz monitor But would it matter for us only with 60Hz monitors? How /in what way is it different at 144+ vs 60fps? So you don't use frame limiter, and you get 144+ even with full grid?

 

Ok, here is couple of good "in the nutshell" kind of articles about frames per second in sim racing.

http://thesimpit.com/en/news/comments/To-lock-framerate-or-not-to-lock-framerate

http://steamcommunity.com/app/241560/discussions/0/34096318669939263/

 

I don't have Vsync enabled.
I don't lock my framerate.
I don't have stutters.
I don't see screen tearing.
I am not convinced that a framerate of 120fps makes that much of a difference to a framerate of 60fps.

 

AC has physics and graphics on different threads, so in essence it doesnt.

 

With SLI and triples, on my system, 60 fps creates a massive input lag. With 120 fps I get a little tearing, and the input lag is tolerable.

Also, SGSS looks awesome, and doesn't take much of a hit on my system, Setting AA ingame from 2x to 4x makes a massive difference, though. Basically going from 115+ to 75fps. So i'll live with a little shimmering and have acceptable performance, looks and latency.

edit:
Played some more with settings. Now getting around 140+ fps with triples 1080p, and the game never looked better. Thanks for the tip!

 

Yeah, the monitor is outstanding, 144hz is well worth it IMO! If you have a 60hz, you're right, fps over 60 is visually irrelevant. I see a huge difference between 60fps vs 120+fps, particularly on replays, but also when racing. Movement looks much more smooth, the sense of speed is increased, and Kunos' physics really shine. Every slight movement of the cars ahead of you and around you is apparent, and during replays every bump, dip and roll of the road is shown with glee-inducing suspension movement.
I generally cap frame rate to AC's 7ms/142.9fps and leave VSync off, but every now and then I switch it around, dunno why. I'm always tinkering and chasing after better visuals I guess
I never run full grid, usually 16 cars for heavy tracks... Nord, Spa, Monza... and 20 cars for others, Nurb GP and Mugello seem pretty well optimized (it's the dang shadows, every track with a lot of trees and shadows just kills performance). I set myself 2nd last on the grid and try to work my way through the field, it's rare when I can pass more than 10-12 cars anyway, so a full grid for me is just a waste.

 

thanks for the tip! much better with this CSAA thing!

 

Thanks. Your originally suggested setting seems good for me. Showing similar quality it gives more fps rather than when I used SGSSx4.

BTW I feel a little more aliasing when I turn off FXAA in AC ingame's PP setting. Can you please clarify what did you modify to turn off FXAA? Also LOD bias 0.3 means -0.3?

As I'm not graphic setting guru, please accept my ignorant question.

 

Well, in my original settings, I had enabled FXAA in Nvidia Inspector (which appears to be better quality than AC in-game FXAA). But FXAA really does blur a lot, so I opted to switch it back off. Problem is, like you said, even with the AA/CSAA/SGSS settings, turning off FXAA produces some more aliasing and LOD flickering. The LOD bias setting of 0.3 (not -0.3) softens the aliasing and texture flickering (anywhere between 0.3 to 0.5 looks good IMO). Setting LOD bias to -0.3 would do the opposite, it will sharpen the on-screen image even more and produce more jaggies/flickering. I think 0.3-0.5 is a good balance, it softens enough but still keeps a sharp image overall.

Also there are some environmental objects that will still appear aliased even with these settings, but not enough to be annoying I think. These settings look great when moving/racing, much of the aliasing disappears... however, when not moving, or when taking a screenshot/picture in-game, aliasing is quite obvious. Can't have it all I guess!

 

I'd like to add to that, that alot of it also has to do with the sharpness settings of your monitor.

 

How to get rid of the blurred white lines on the track? Even with 16x AF. It is strange because the KS tracks are ok but some mod tracks have horrible white lines in the distance from the cockpit view. Is it up to the modders to have better texture ? (Mipmap texture ?)

Thanks.