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

Picture gallery  (enlarge to view source)

Author: Raffael Vötter (Apr 23, 2010)

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