Homeworld 2
Radeon X800XL
GeForce 6800GT
You have to look real close (and we do mean REAL close), to see the difference between the three AA and AF shots. Look at the upper right corner (the plateau with the shadow). You could definitely see the NVIDIA's High Quality has a sharper image (without the artifacts seen on the X800XL), but the Quality settings is more blurred. On the upper left of these shots (still on the plateau), you could see High Quality does a slightly better job. Image quality under NVIDIA's Quality settings is similar to the X800XL here. However, remember that Homeworld 2 is an RTS game, where much of the gameplay is not played in this mode. Most of the time, you'll be looking at these from a distance, so these differences are not really noticeable in gameplay. We can see 4x AA between the X800XL and GeForce 6800GT is pretty much the same - or are they?
Aliasing in motion
Radeon X800XL
no AA
2xAA
4xAA
6xAA
GeForce 6800GT
no AA
2xAA
2xQ AA
4xAA
8xSAA
After looking at these image sequences, you can surely see that ATI's 4x is more effective than NVIDIA's. Even throwing more samples (8xS) is useless. Oddly enough, it is NVIDIA's 2xQ mode that's up to the task. So, NVIDIA's 4x is definitely not the same with ATI's 4x. If we were to rely on static screenshots alone, we would not be aware of this.
Star Wars: Knights of The Old Republic
Radeon X800XL
GeForce 6800GT
Let's look at anisotropic filtering between the three shots. See the far grate on the floor on the left - you could see artifacts on NVIDIA's Quality images. The High Quality settings and ATI's 'Application Preference' has no artifacts. You can also see this on the floor grate on the right - definitely banding artifacts in Quality. This is expected since NVIDIA's High Quality and ATI's Application Preference is pretty much the same or at least have very close MIP levels. 4x AA of the two cards are pretty much the same, but let's take a look at them in motion.
Aliasing in motion
Radeon X800XL
no AA
2xAA
4xAA
6xAA
GeForce 6800GT
no AA
2xAA
2xQ AA
4xAA
Well, they are pretty similar. You could definitely see both cards does a decent job in reducing artifacts (look at the white panel on the right). However, both cards are not able to remove aliasing entirely. We still see much aliasing from both cards - look at the ceiling and the table just as we're walking towards it. Even ATI's 6x AA is not up to the task. We need to use an even higher resolution if we want to 'mask' this aliasing by giving the cards more pixels to draw to. Wait a minute, you'll notice that there's no image sequence of NVIDIA's 8xS AA. Well, unfortunately the 8xS AA mode (known to the game as 8x mode) only work correctly if you disable shadows. So, we feel there's no point in testing it since image quality is not getting any better and you have to settle for less effects.
So, while MIP levels diagnostic does provide an indication of 'better' texture filtering, we should always look at in game screenshots to determine what's acceptable to our eyes (and what's not). If an application supports setting anisotropy levels, NVIDIA's High Quality settings and ATI's Application Preference is evenly matched. For applications without support of anisotropic filtering, ATI's forced anisotropic filtering is better than NVIDIA's Quality, but not up to NVIDIA's High Quality. Even so, remember that the artifacts are very small and not noticeable (especially in motion).
For anti aliasing, we could clearly see ATI has the more effective anti aliasing implementation compared to NVIDIA. While it's not 100% effective, in some cases (Homeworld 2) it's able to remove aliasing quite effectively (even under 2x) than NVIDIA's implementation. ATI's 6x mode is also more 'compatible' with games (SW:KOTOR) than NVIDIA's 8xS. Sadly, neither mode is really that much more effective than 4x in removing aliasing. So, image purist will really have to crank up the resolution to at least 1600 x 1200 with 4x AA to 'mask' aliasing. This is more effective than using 6x or 8xS AA in 1024 x 768 or even 1280 x 960 / 1024.
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