Image Quality (Cont): Enter ATI, Performance Impact
Comparing the ATI and NVIDIA supersampling methods we see that while the NVIDIA method is blurrier, it's also more effective at eliminating jagged edges. Based on what we know about NVIDIA's supersampling method as forced by nHancer and ATI's historical approach, the different image results from the use of two different pixel sampling methods.
NVIDIA uses an ordered grid approach, which samples every pixel in an image the same way from the same points. This is less effective on 45' angles or on lines that are nearly (but not quite) perfectly horizontal or vertical. If you want to see an example of the effect, click the left thumbnail above. At certain angles, the human perceives the lines as more or less aliased. In years past, ATI relied on what it calls sparse grid super sampling, claiming that this method was better at handling angled lines. In theory, the ATI images are applying 8x sparse grid compared to NVIDIA's 4x4 ordered grid, but since we're comparing a buggy driver against a game that's been forced to run in DX9 mode for comparison shots, we can't say with 100 percent certainty that the proper modes have been applied.
We've focused on 4xSSAA because it's the sweet spot between visual quality and performance; 2x supersampling is available but doesn't improve image quality much. 8xSSAA is also technically available, but produces a very blurred image. In addition, the performance penalty from 8x drives even a pair of GTX 480's in SLI mode to their knees in DX11.
Testbed: Intel Core i7 980X @ 4.2GHz, 6GB DDR3, 2x GTX480's in SLI