The new 8x, 12x and 16x Anti-Aliasing on GeForceFX

April 13, 2003 / by aths & Leonidas, translation by Zeckensack & nggalai / page 6 of 6

   Conclusions and Delusions

As a sanity check we probed the latest nVidia driver for possible new anti-aliasing modes with a special aTuner build (the anti-aliasing registry key can represent 16 distinct values). But we came up empty, the 42.74 and 43.45 version drivers don't recognize any other values. Here's the summary of all available anti-aliasing modes:

AA modes	nVidia Detonator name	aTuner name	official supported by
2x rotated grid multisampling (EER 2x2)	Direct3D & OpenGL: 2x	Direct3D & OpenGL: 2x	GeForce 3/4/FX
4x ordered grid multisampling (EER 2x2)	Direct3D & OpenGL: 4x	Direct3D & OpenGL: 4x	GeForce 3/4/FX
2x rotated grid multisampling + 1x2 ordered grid supersampling (EER 2x4)	Direct3D: 4xS	Direct3D: 4xS	GeForce 3/4/FX
4x ordered grid supersampling (EER 2x2)	official not supported	Direct3D: 4xSS	official not supported
4x ordered grid multisampling + 1.5x1 supersampling (EER 3x2)	Direct3D: 6xS	Direct3D: 6x	GeForceFX 5600/5800
4x ordered grid multisampling + 2x1 ordered grid supersampling (EER 4x2)	Direct3D: 8x	Direct3D: 8x	GeForceFX 5600/5800
2x rotated grid multisampling + 2x2 ordered grid supersampling (EER 4x4)	OpenGL: 8x	Direct3D & OpenGL: 8xS	official not supported
4x ordered grid multisampling + 1,5x2 ordered grid supersampling (EER 3x4)	Direct3D: 16x	Direct3D: 12x	GeForceFX 5600/5800
4x ordered grid multisampling + 2x2 ordered grid supersampling (EER 4x4)	OpenGL: 16x	OpenGL: 16x	GeForceFX 5600/5800

In conclusion nVidia now offers seemingly higher anti-aliasing modes than ATi (6x maximum), but they do so with mostly ineffective subpixel grids, especially in the highest settings. This way these modes eat a lot of performance and impress with their names, yet they are not (or at best marginally) better than 4xS, which has been introduced with the GeForce4 Ti and is also available on GeForce3 if you're using a tweak tool.

So far nVidia also didn't fulfill their promise of introducing new anti-aliasing modes with non-rectangular subpixels grids, a promise they made with the announcement of the GeforceFX (see the GeForceFX preview at ExtremeTech, search for "rectangular") - of the five modes using more than four subpixels, four still use rectangular grids. Image quality does not improve in any meaningful way, as is demonstrated by the 8x (rectangular) vs. 8xS (45 degrees rotated) Direct3D comparison.

8xS anti-aliasing is the only mode that really exceeds the quality achieved with 4xS (it's also the only "new" mode that uses a non-rectangular grid) and it's the only mode that can compete with ATi's 6x anti-aliasing. Strangely enough nVidia's Detonator control panel only exposes this mode for OpenGL, and offers a clearly inferior 8x mode for Direct3D. A tweaking tool like aTuner is absolutely required to get the better one of the two 8x modes for Direct3D, at least at the moment.

With the higher-labelled 12x (Direct3D) and 16x (OpenGL) modes, nVidia seems to have missed the mark: Both offer little if any quality gains beyond 8xS. The 16x setting under OpenGL also performs worse than 8xS. And of course the 12x mode for Direct3D bears the name "16x" in the Detonator panel. This is completely unjustified and needs to be corrected.

We strongly feel nVidia should spend some effort on improving their anti-aliasing technology. The higher-end GeForceFX series cards are significantly faster at anti-aliasing than any GeForce4 Ti, but regarding the available modes very little progress has been made since 4xS. All higher modes offered by nVidia fail to further improve image quality, and/or are too slow to be generally useful.

Anti-aliasing benefits much more from intelligent solutions for subpixel grids and architectural tweaks than it does from increases in sheer rendering power as implemented in the GeForceFX series. This is exactly what nVidia once demonstrated when they introduced the GeForce3 with its then ground breaking multisampling implementation - it's high time for this kind of innovation to lift its head again.