ATI's SMOOTHVISION - The key to its "success"

ATI vs. NVIDIA: 2X AA Quality

With a better understanding of SMOOTHVISION we can now revisit the issue of AA quality, let's go to the screenshots (Note: since these screenshots are so small we'd suggest setting your screen resolution to no greater than 1024 x 768):

ATI Radeon 8500 AA Off

NVIDIA GeForce3 Ti 500 AA Off

With AA turned off, the screenshots look identical; they are both equally blurry and aliased.

ATI Radeon 8500 2X Performance AA	ATI Radeon 8500 2X Quality AA
NVIDIA GeForce3 Ti 500 2X Multisampled AA + Aniso	NVIDIA GeForce3 Ti 500 Quincunx Multisampled AA + Aniso

Because of the GeForce3's use of multisampling it needs to have anisotropic filtering enabled to level the playing field, this also reduces performance a bit as you will see in the performance section of this review. Because of ATI's supersampling and NVIDIA's anisotropic filtering, the texture clarity of the shots look very similar. We can tell some of the differences in edge AA quality (if you look closely you can see that the quality AA mode and both of NVIDIA's modes actually take more samples along the topmost platform) but in order to better see the differences we'll have to consult our Serious Sam screenshots:

ATI Radeon 8500 2X Performance AA	ATI Radeon 8500 2X Quality AA
NVIDIA GeForce3 Ti 500 2X Multisampled AA + Aniso	NVIDIA GeForce3 Ti 500 Quincunx Multisampled AA + Aniso

Here we can easily see that the edge AA quality of ATI's 2X performance AA mode is inferior to NVIDIA's 2X mode. If our hypothesis about ATI not rendering as many samples in their performance mode is true then it would explain why. ATI's 2X quality mode is very similar to both of NVIDIA's AA modes depicted here and falls in-between the two.

2X AA Conclusion: With anisotropic filtering enabled, NVIDIA's 2X and Quincunx multisampled AA modes are significantly better than ATI's 2X Performance AA mode. But you must enable anisotropic filtering in order to gain this overall advantage, otherwise the only advantage is in edge anti-aliasing at the sacrifice of blurrier textures. ATI's 2X Quality AA mode falls in-between NVIDIA's 2X and Quincunx modes in terms of edge AA quality and is easily just as good as both solutions with anisotropic filtering enabled.