Why does Nvidia choose FXAA over SSAA?

[Raging Beard]

I have a high spec PC with a GTX1080 and NMS runs smooth as silk with everything as high as it will go and SSAA x4. Why does the GeForce Experience say that FXAA is optimal rather than SSAA?

[𝓕𝔁]

Because - GeForce Experience....

Half the time it tells me to use lower resolutions etc, even though I get a solid 60 fps @ 4k in the games it wants to "Optimise" lol.

[AgaNagA]

Because the GeForce experience is a sucky one

[Raging Beard]

Lol fair enough!

[Amenophys]

From Uber dev's team (https://forums.uberent.com/threads/fxaa-ssaa-instead-of-aa.34382/)

"SSAA (super-sampled anti-aliasing) is the original anti-aliasing technique. In the average use case it can be best described as rendering the scene at a higher resolution and down sampling to the screen resolution, so at 2x SSAA a 800x600 game is rendered at 1600x1200 and shrunk to 800x600. This means for every displayed game pixel four points were rendered and combined.

MSAA (multi-sample anti-aliasing) is essentially the same idea as SSAA, render multiple sample points and combine for each pixel. However 2x MSAA only renders two points per pixel instead of four points like SSAA, and only the opaque objects. Transparent objects are rendered separately and added afterwards. 4x and above render that number of points at randomized or offset positions with in each displayed pixel to try to reduce aliasing over what the classic SSAA is generally capable of. This means 4x MSAA is generally superior to 2x SSAA in reducing jagged edges on opaque object edges at a slightly reduced quality of transparencies.

So, here's the kicker. FXAA looks great in screenshots or if nothing is moving on screen. In motion it does very little to reduce perceived aliasing. It also has a tendency to cause problems with UI elements and text when forced on via drivers.

I've seen some articles gush over Crysis's implementation of SSAA as being superior to MSAA techniques... but they're not doing anything particularly special with their SSAA, it's just their games have a lot of transparent objects and sharp edges created by shaders rather than geometry. In these cases SSAA will always win over current MSAA techniques visually. Since MSAA and even adaptive techniques are all based on geometry edges, as more games use complex shaders and transparency to create detail these techniques become less effective."