Request - allow change to FFR resolution multipliers

[vrnord]

I don’t know if the resolution multipliers of the 3 rings are unchangeable due to how VRS works or if it uses values you set, but I wonder if you could expose those resolution multipliers in the config file for users to change?

Specifically, for me in SkyrimVR, I have to set a SGSSAA value in Nvidia Profile Inspector that matches the resolution scale in the rings to remove very obvious visual anomalies (something about shadows turning white on textures with transparency like foliage, plants etc). So 2x SGSSAA fixes the first ring but leaves the rest with shimmering white shadows, and increasing to 4x SGSSAA also fixes the middle layer. However 8x SGSSAA does nothing more to fix the outer layer, probably because it is set to 16x FFR. Meanwhile there is no setting for 16x SGSSAA. So my theory is if I could set the outer ring to 8x then SGSSAA would fix it too and I could leave that outer ring more in my field of view, and thus improve my performance (right now I am setting that last radius really high so I don’t see any of the outer ring).

[philosoma]

What if you set two of the rings to the same value and continue keeping the outer ring just out of view?

[fholger]

Are you sure you are even getting any performance gains this way? As in, actually measured? Because SGSSAA is, to my knowledge, crazy expensive, and having it running at 4x or even 8x should easily offset any performance gain you might have had with the fixed foveated rendering.

It's unclear to me how it would fix the issue, anyway. My theory would be that it actually cancels out the reduced render resolution from VRS by forcing a higher multisampling count. Then again, I haven't been able to observe the issue myself and can only speculate what it even is.

[vrnord]

What if you set two of the rings to the same value and continue keeping the outer ring just out of view?

That is what I am currently doing. It works but I think there is more performance to be gained if I could expand the outer circle.

[vrnord]

Are you sure you are even getting any performance gains this way? As in, actually measured? Because SGSSAA is, to my knowledge, crazy expensive, and having it running at 4x or even 8x should easily offset any performance gain you might have had with the fixed foveated rendering.

It's unclear to me how it would fix the issue, anyway. My theory would be that it actually cancels out the reduced render resolution from VRS by forcing a higher multisampling count. Then again, I haven't been able to observe the issue myself and can only speculate what it even is.

I ran the test: same run through the same GPU-bottlenecked area from the same save 3 times, with TAA off and VR FPS Stabilizer (which dynamically changes settings to improve frametime) disabled:

1. first with just FSR @ 0.77: result 81fps average. Lots of aliasing.
2. second with FSR 0.77 + FFR @ 0.4, 0.6 & 1.1 (radius of each ring): result 85fps average. very obvious visual anomalies (see screenshot attached). Lots of aliasing.
3. third with FSR 0.77, FFR 0.4, 0.6 & 1.1 + SGSSAA x4: result 80.5fps average. By far the clearest and least aliased image.

So a couple observations:

1. At least with my current FFR radius settings SGSSAA negates the benefits of FFR. However due to the visual anomalies not being corrected by SGSSAA in the outer 16x radius I am forced to almost eliminate that outer radius so the vast majority of the image is being rendered at 4x instead, which limits FFR's performance improvement to just ~5fps: potential room for improvement there.
2. 4x SGSSAA cost ~4.5fps, which is not free but also not a massive cost, and is essentially free when combined with FFR. Most reshade shaders are equal or greater cost, and SGSSAA is also a massive visual upgrade. I don't need TAA or CAS and it looks like it is running at a higher resolution than it is.

Running SkyrimVR on 3090 with Reverb G2 SteamVR 100%.

Note about attached image: I coloured the center purple so you can clearly see it, but most foliage outside the central circle has weird white flickering where shadows are or should be. It seems to not affect foliage within a few feet of me but affects foliage even quite a distance away (like on the opposite side of Lake Ilinalta), and shows more in some lighting than others.

You can see it in the tree branches above and to both sides of the circle, and in the low shrubbery on the road to the left of the circle. It's harder to see in the screenshot but the distant trees behind the fort also have this but it looks more like an off-coloured ring in the trees since you can't see individual branches at that distance.

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[fholger]

Oh sorry, I have seen screenshots of it before, but what I meant is I can't reproduce it. My vanilla Skyrim installation so far has not exhibited the issue, so I cannot investigate the actual cause.

One more question: if you choose a very low radius for the first circle (e.g. 0.2) and then enable SGSSAA to "fix" its rendering artifacts, can you still see the ring in your headset? At that low radius, it should be very obvious when the render resolution drops.

[vrnord]

Tested 0.15 for the middle radius, and while I can't see the outline/shape of the inner circle, everything except the very centre of my field of view is pretty blurry. So the FFR is still rendering with SGSSAA enabled.