For FXAA, the effect of values 2, 4, and 6, can be seen in the above image the smoothing of jagged edges becomes better and better. For either Anti-Aliasing method, a value of 0 used with r.PostProcessAAQuality will disable the effect.
↑ Scalability Reference - last accessed on ' Adjusting the Anti-Aliasing quality level using the r.PostProcessAAQuality console command will adjust the quality of whichever Anti-Aliasing method you are using (FXAA or Temporal AA).
