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AMD Radeon HD 2900 XT - Anti-Aliasing Evolution
It seems that with each new architecture launch there’s an enhancement to the anti-aliasing techniques seen on the previous generation. First up, the HD 2000 series of cards will happily run all the previous versions of ATI/AMD anti-aliasing, including proprietary methods like Temporal AA, which appeared with the X800 cards and Super AA which was originally seen on the X850 CrossFire setup.
For a very long time now, ATI has been trying to convince gamers and journalists alike that there is more to graphics technology than frame rates. The company has been urging potential buyers to look at image quality and base their purchase on just how good things look, rather than just how fast they run. Of course this was an obvious course of action for ATI for many years, since the Radeon cards were widely considered to have superior filtering, although things became far less clear cut when nVidia launched the GeForce 8 series and significantly raised the bar on its filtering.
As graphics engines have improved and become more jaw droppingly beautiful to behold, serious game players have begun to place good anti-aliasing at the top of their list of importance. After all, there’s nothing worse than a beautifully rendered and lit scene that’s spoiled by jaggy diagonal lines, especially when those edges shimmer distractingly while you’re wandering around. Personally I’d far rather run a game at a slightly lower resolution with a decent degree of anti-aliasing enabled, than run it at a higher resolution with none!
AMD showed the new anti-aliasing off to good effect, but we'll reserve judgement until we've viewed CFAA with edge detection ourselves.
As part of the Radeon HD 2000 series AMD has introduced Custom Filter anti-aliasing (CFAA), which theoretically applies anti-aliasing where it’s most needed. Key to CFAA is the edge detection filter, which applies more samples to pixels located along edges to smooth off jaggies. Meanwhile pixels that are not located along edges have fewer samples applied, therefore reducing the amount of load created by the anti-aliasing passes.
There are several potential benefits to CFAA, not least of which is the fact that the intensive anti-aliasing is only being applied where required. AMD also says that there will be a reduction in texture shimmering and less blurring of fine detail.
Unfortunately the current HD 2900 XT driver didn’t support the edge detection function of custom filter anti-aliasing, but as soon as I get hold of one that does I’ll put it through its paces and see if it lives up to AMD’s promises.