High Quality AF

One of the greatest things about the newest high end hardware from NVIDIA and ATI is that advanced filtering features can be enabled at any resolution while still maintaining playable framerates. It may take developers a little while to catch up to the capabilities of the X1800 and 7800 lines, but adding value through advanced quality features is definitely a welcome path for ATI and NVIDIA to take. For this launch, ATI has improved their AA and AF implementations. We also have two brand new features: Adaptive AA and Area Anisotropic filtering.

Starting with Area Anisotropic (or high quality AF as it is called in the driver), ATI has finally brought viewing angle independent anisotropic filtering to their hardware. NVIDIA introduced this feature back in the GeForce FX days, but everyone was so caught up in the FX series' abysmal performance that not many paid attention to the fact that the FX series had better quality anisotropic filtering than anything from ATI. Yes, the performance impact was larger, but NVIDIA hardware was differentiating the Euclidean distance calculation sqrt(x^2 + y^2 + z^2) in its anisotropic filtering algorithm. Current methods (NVIDIA stopped doing the quality way) simply differentiate an approximated distance in the form of (ax + by + cz). Math buffs will realize that the differential for this approximated distance simply involves constants while the partials for Euclidean distance are less trivial. Calculating a square root is a complex task, even in hardware, which explains the lower performance of the "quality AF" equation.

Angle dependant anisotropic methods produce fine results in games with flat floors and walls, as these textures are aligned on axes that are correctly filtered. Games that allow a broader freedom of motion (such as flying/space games or top down view games like the sims) don't benefit any more from anisotropic filtering than trilinear filtering. Rotating a surface with angle dependant anisotropic filtering applied can cause noticeable and distracting flicker or texture aliasing. Thus, angle independent techniques (such as ATI's area aniso) are welcome additions to the playing field. As NVIDIA previously employed a high quality anisotropic algorithm, we hope that the introduction of this anisotropic algorithm from ATI will prompt NVIDIA to include such a feature in future hardware as well.

We sat down with the D3DAFTester to show the difference between NVIDIA and ATI hardware with and without the high quality mode enabled. Here's what we ended up with:

NVIDIA 7800 GTX AF

NVIDIA 7800 GTX AF

Mouse over to cycle images

High Quality AF does come with a performance hit. We tested Far Cry at 1600x1200 on a Radeon X1800 XL and saw a performance drop from 76.3 fps to 71.2 fps. This is quite acceptable on high end hardware, but may not be a viable option for everyone.
Memory Architectures Adaptive AA
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  • JarredWalton - Wednesday, October 5, 2005 - link

    Hence, the non-existence of 7600 and 7200 (or whatever) cards from NVIDIA. But ATI needed to get SM3.0 into budget and mid-range cards - not because it's tremendously useful, but because they're losing the marketing campaign on that item.
  • Phantronius - Wednesday, October 5, 2005 - link

    Wheres the fucking Battlefield 2 numbers?????
  • Dudeeeeeee - Wednesday, October 5, 2005 - link

    What about testing this card with games we actually play? Good game...
  • KayKay - Wednesday, October 5, 2005 - link

    I read most of the r520 reviews this morning and I decided to read anandtech's review, since i trust yours over most others. I was rather disappointed with the layout and choice of tests.

    All around the web, the result i gathered was that the x1800xt was definitely better than the 7800gtx in a number of areas and if i had read anandtech's review first, would have been totally misled.

    I am an NVIDIA user probably for LIFE but this review didn't seem to do ATI justice
  • bob661 - Wednesday, October 5, 2005 - link

    quote:

    I am an NVIDIA user probably for LIFE but this review didn't seem to do ATI justice
    Reviews aren't supposed to be favorable they're supposed to present facts so that WE the consumer can make informed purchase decisions. And right now, ATI doesn't present a good bang for the buck.
  • KayKay - Wednesday, October 5, 2005 - link

    the review wasn't structured in a way to present a fair comparison of the cards is all im saying. look no further than some of the other websites that reviewed todays launch
  • bob661 - Wednesday, October 5, 2005 - link

    It was easy for me. What are you looking for? The X1xxx's were compared to the 7xxx's. Are you looking for an ATI landslide or are you looking for a comparison?
  • Chadder007 - Wednesday, October 5, 2005 - link

    I was hoping that the X1600 would perform better, but for the price 6600GT and X800GTO >>>> X1600 parts. Sad. :(
  • Griswold - Wednesday, October 5, 2005 - link

    Probably the weakest review i've seen here at AT so far. The benches are more than just confusing. Some benches only show the XL, some only the XT and some both. Not good.
  • DigitalFreak - Wednesday, October 5, 2005 - link

    Agreed. I'm not a stickler for perfect grammer, but the grammer & spelling quality of AT articles has gone down hill tremendously in the past year!

    Seems you guys have just been throwing stuff together at the last minute to try and make a deadline. Anand - you need to step in here and get these guys back on track. It's hurting both your and your sites reputations.

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