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Sparse Grid SSAA with DX11 & DX10

Geforce GTX 480/470 with unmatched image quality in modern games

Nvidia's Geforce GTX 400 series is evolving into the optimal solution for quality oriented gamers: For the first time since the introduction of DirectX 11 and 10 it is now possible to use full screen Supersampling Anti-Aliasing with the two APIs. PC Games Hardware has the facts.
Geforce GTX 400: SGSSAA under DX11/10
Geforce GTX 400: SGSSAA under DX11/10 [Source: view picture gallery]
User Blaire of the 3D-Center Forum made a sensational discovery: His new SLI setup with three Geforce GTX 480s seemed to display full screen Supersampling Anti-Aliasing (SGSSAA) under DirectX 10 and 11. Some days later more and more evidence became available and thus PC Games Hardware took a look at the matter. Our preliminary conclusion might make some quality oriented gamers really happy: With a GTX 480 or 470 it is possible to apply the best available Anti-Aliasing on the whole image - under DirectX 10 or 11. No other graphics card can do that at the moment - not even AMD's Radeon HD 5000 series which delivers SGSSAA under DirectX 9.

SGSSAA with DirectX 11/10: Cost-benefit analysis
If you don't know the abbreviation SGSSAA then you might want to take a look at our HD 5870 review where we explain the feature. In fact Supersampling Anti-Aliasing delivers the best image smoothing available today. SGSSAA is, in contrast to Multisampling Anti-Aliasing (MSAA), applied to the whole image and because of that textures or shaders do not flicker anymore. The drawback is the extreme workload: With 4x SSAA the graphics chip has to sample each pixel not only once but four times. Thus the framerate drops noticeably.

The novelty delivered by the GTX 480/470 is that SGSSAA works under DirectX 11 and DirectX 10. But under Direct 3D 9 the trick doesn't work. So if you want to play games like Battlefield: Bad Company 2, Crysis Warhead, Colin McRae: Dirt 2, Metro 2033 and Just Cause 2 with the best possible graphics, this development might be interesting for you.

SGSSAA with DirectX 11/10: How-To
TSSAA: Necessary for SGSSAA under DX11/10
TSSAA: Necessary for SGSSAA under DX11/10 [Source: view picture gallery]
The curious thing about the findings of the 3D Center Forum is that this new effect is caused by a feature that has been available for years: Transparency Anti-Aliasing (TAA). Under DirectX 11/10 the enhanced implementation of the GF100 is applied to the whole scene. If this is done on purpose, has not been clarified yet. We have informed Nvidia and our inquiry has been forwarded to the driver team. As soon as we receive feedback, we will inform you about it.

In order to get the best possible smoothing in DirectX 10 and 11, you need a Geforce GTX 480 or GTX 470. Our tests with a GTX 285 confirm that the feature isn't working on older cards (yet). In the Nvidia Control Panel you have to select 2x, 4x, or 8x Anti-Aliasing - Transparency. 8x delivers the best quality. After that you choose an Anti-Aliasing level in the game you want to play - 8x AA for example. 8x in-game AA plus 8x TSSAA in the driver result in 8x full screen SGSSAA - and a noticeable drop of the framerate.

Although each pixel is sampled several times, the driver doesn't necessarily adjust the Texture LOD (the level of detail in a certain distance) automatically. This also indicates an accidental implementation of the full screen application. With an adjustment of the LOD bias a higher level of Anisotropic Filter without flickering would be possible - in the current state you "only” get a much settled image. Manual modifications are not possible since the common tools that offer LOD adjustements are for Direct 3D 9, or older, only.

The comparisons below show the differences between pure MSAA and SGSSAA under DirectX 11 and DirectX 10. What do you thing of the feature?

Click to select Anti-Aliasing settings
Hier kommt der Alternativtext rein
Click to select Anti-Aliasing settings
Hier kommt der Alternativtext rein
Click to select Anti-Aliasing settings
Hier kommt der Alternativtext rein

Picture gallery  (enlarge to view source)

Author: Raffael Vötter (Apr 23, 2010)


Comments (9)

Comments 6 to 9  Read all comments here!
ruyven_macaran Re: Geforce GTX 480/470 with unmatched image quality in modern games
Super Moderator
04.06.2010 22:30
Nvidia definetly experimented with a lot of mixed modes against the R300, but I admit, that I can't really remember, as I didn't care at all for AA in these times. If they offered SSAA, it would definetly been OG.
The same should apply for current nHancer modes (though Nvidia has now released a tool to force SGSSAA, iirc this has not yet been implemented in nHancer. It's buggy anyway)
Bo_Fox Re: Geforce GTX 480/470 with unmatched image quality in modern games
Junior Member
03.06.2010 00:46
Quote: (Originally Posted by ruyven_macaran)
Iirc (which might be not the case, as I hardly use any AA)...:
ATIs SGSSAA is DX9 only (perhaps DX10, but not DX11) and Nvidia up to now only supported RGSSAA (rotated grid) not the slightly better (or supposed to be slightly better - I never understood why it should be supperior at 8 samples and higher) SGSSAA (sparse grid), though they did it with all DX-versions. So this should be both a SGSSAA@Nvidia and SGSSAA @DX10&DX11 first timer, but it is not the first time of SSAA in general beeing used with DX10.

(the original german edition puts additional emphasis on the sparse-grid, probably the translator missed this point)

I thought that NV originally suported OG-SSAA modes wayy back then when combined 8xS mode was officially supported during the Geforce FX days. I mean, if I use nhancer with my 8800GTX right now to force any of the SSAA modes, is it OG-SSAA or RG?
ruyven_macaran Re: Geforce GTX 480/470 with unmatched image quality in modern games
Super Moderator
24.04.2010 14:12
There is no "pure" __SSAA. The first two letters just describe the arrangement of subsamples - and you have to arrange them somehow. So you have either OGSSAA, RGSSAA or SGSSAA, with ordered grid beeing the most senseless (very good at smotthing diagonal lines, which will show only 1x1 pixel sized "steps" anyway, but with almost no effect on near vertical/horizontal lines, that give those anoying stair-like effects wandering around at light movements), rotated grid being much better (same as before but 45° turned, so most effect were it is most needed) and sparse grid generally considered the best.

What you might think of, is the difference between full-screen ??SSAA and edge detect or transparency ??SSAA. But these to not describe methods of SSAA (like OG/RG/SG), but forms of application - and obviously the one affecting the whole picture is superior (in slowing down your hardware )

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