Basis of the translucency's screen percentage (Experimental) 0: Uses the primary view's resolution (notably scaling with r.ScreenPercentage and r.DynamicRes.* 1: Uses the secondary view's resolution (temporal upscale's output resolution)
Usage
r.Translucency.ScreenPercentage.Basis [value]
Set via the console (~) or in DefaultEngine.ini / DefaultGame.ini.