Strange interaction between fSunBaseSize + TAA with night sky

[darkrain261]

It's hard to describe this problem but whenever I turn on TAA, my night sky will have an area that will be blurrywhen I move my mouse. You can see it here: 

In case you can't see with the YT quality, you can notice that the star in the middle look like it flickering while the ones in the bottom corners don't.

I tested in vanilla with Etheral Cosmos, fSunBaseSize value 220, but you can produce this problem with any night sky mods and TAA on, or even with vanilla night sky.

Here is another user encountered the same problem: 

 

At first I thought this problem is only TAA related, because when I turn it off or use FXAA then this issue will disappear. But after some testing, I notice that the effect will be more noticeable with RAID Weathers enabled, and I found that this mod has some edits to ini, with fSunBaseSize changed from vanilla value to 220. So I tried to messing around with that setting. Here is the result:

1) With vanilla value 425: the area border expands toward the horizon (around 30-40 degree about the horizon), making the sky blurry/flickering in a bigger area.

2) RAID Weather value 220: as shown in the video, this makes the issue more noticeable, the area is now smaller and more distinguishing as the area surround it doesn't have this blurry effect.

3) Value 0: the area disappeared.

4) Value 1000:  the whole sky is now blurry with mouse movement.

 

Turning of TAA or adjust the value might temporarily fix this issue but they are not the best ideas, because the setting is tied to the sun's base size. Too high value will make the sun gigantic and the whole night sky blurry, or set value to 0 will make the sun disappear, so I'm trying to avoid this. So I'm asking if anyone know the answer to this problem. Thank you!

Edited August 7, 2023 by darkrain261

[darkrain261]

Update: just found out that the area will change depending on the hour, so at 0:00, it will be directly on top of my character. From 8pm to 23pm, it is located in the west and from 1am to 5am, it's at the east. I think it's because how Bes designed the sky, it's a spherical with symmetry in 2 hemispheres, so even the sun doesn't come out at night, the setting fSunBaseSize  for it still affect the night sky.

[DoubleYou]

Enb has a deblurring fix for TAA. It also has a Reshade addon for this. Perhaps that may help/affect this. 

[darkrain261]

Yes, Enb and Reshade seems to be the only ways to fix this. I haven't tried enb but with Reshade, I have tried a couple of presets and setting with SweetFX's SMAA but no use so far. I also tried Skyrim Upscaler with FSR2 and XeSS option but the result is the same.

Besides I want to know why fSunBaseSize can cause this issue. I think it only affects the sun but don't know why it could create this blurry area during night time.

[darkrain261]

1 hour ago, DoubleYou said:

Enb has a deblurring fix for TAA. It also has a Reshade addon for this. Perhaps that may help/affect this. 

I just tried some more presets and options, the blurry of TAA is indeed reduced but that blurry area in the sky is still there. It's only blurry/flickering when I move camera and only in that specific area in the sky. So I don't think it has anything to do with TAA blurry, but somehome with TAA on, this happens.