Angle-Independent Anisotropic Filtering At Last

For a number of years now the quality of anisotropic filtering has been slowly improving. Early implementations from AMD and NVIDIA were highly angle-dependent, resulting in a limited improvement to image quality from such filtering. The angle-dependent nature lead to shimmering and other artifacting that was not ideal.

As of the previous generation of cards, the quality of anisotropic filtering had become pretty good. NVIDIA’s best filtering mode was pretty close to angle-independent, and AMD’s only slightly worse. Neither was perfect, but neither was bad either.


The Radeon HD 4890


The GeForce GTX 285

However so long as no one had an angle-independent implementation, there was room to improve. And AMD has gone there. The anisotropic filtering algorithm used by the 5000 series is now truly and completely angle-independent. There are no more filtering tricks being used.


The Radeon HD 5870: Perfection

As you can see, the MIP maps in our venerable D3D AF Tester are perfectly circular, the hallmark of an angle-independent implementation. With angle-independent filtering, this effectively marks the end of the filtering arms race. AMD has won, and should NVIDIA catch up in the future the two would merely be tied. There’s nowhere left to go for quality beyond angle-independent filtering at the moment.

AMD tells us that there is no performance hit with their new algorithm compared to their old one. This is a bit hard to test since we can’t enable the old algorithm on the 5870, but certainly whatever performance hit there is, is similarly minor. In all of the testing we’re doing today, you will see results done with 16x anisotropic filtering used.

What you won’t see however is a difference, particularly with our static screenshots. When discussing the matter, AMD noted that the difference in perceived quality between the old algorithm and the new one was practically the same. After looking at matters we find ourselves in agreement with AMD; we were not able to come up with any situations where there was a noticeable difference, beyond the obvious AF quality tests that are designed to identify such changes.

Regardless of the outcome, AMD deserves kudos for making angle-independent anisotropic filtering happen. It’s demonstrably perfect filtering with no speed hit versus the previous generation of filtering; making it in essence a “free” improvement in image quality, however slight the real-world results are. We’re always ready to get better image quality out of our video cards, after all.

More GDDR5 Technologies: Memory Error Detection & Temperature Compensation The Return of Supersample AA
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  • Ryan Smith - Wednesday, September 23, 2009 - link

    The load temp is the same as a single card.
  • ilnot1 - Wednesday, September 23, 2009 - link

    Does anyone have a link to any review that compares 4850's, 4870's, and 4890's in Crossfire against the 5870 & 5870 CF setup?
  • T2k - Wednesday, September 23, 2009 - link

    FWIW: http://www.techpowerup.com/reviews/AMD/HD_5870_PCI...">http://www.techpowerup.com/reviews/AMD/HD_5870_PCI...
  • T2k - Wednesday, September 23, 2009 - link

    Ehh, I meant: http://www.techpowerup.com/reviews/ATI/Radeon_HD_5...">http://www.techpowerup.com/reviews/ATI/Radeon_HD_5...
  • ilnot1 - Wednesday, September 23, 2009 - link

    Thanks T2k, but the only cards that are in Crossfire in that review are the 58XX's. There are no other comparisons to cards in CF or SLI. Since Ryan included some of the most recent nVida cards in SLI I was hoping to find the 48XX's in CF.
  • T2k - Thursday, September 24, 2009 - link

    Basically the rule of thumb seems to be that at 1920x1200 a single 5870 is still slightly slower than 4870X2 and probably slightly faster than a 4850X2 2GB.
    I own the latter so I will wait this time - either they lower the initial price of the 5870X2 or they release a 5850X2, otherwise I'll pass because single 5870 is simply OVERPRICED as it is already.

  • T2k - Wednesday, September 23, 2009 - link

    Seriously: we get a very nice technical background section - then you top it with this more than idiotic collection of games for testing, leaving out 4850X2 2GB, 5850, using TWO stupid CryEngine-based PoS from Crytek, the most un-optimized code producers or WoW, of which even you admit it's CPU-bounded but now CoD:WaW, no Clear Sky, no UT3 or rather a single current Unreal Eninge-based game?

    Benchmarking part is ALMOST WORTHLESS, the only useful info is that unless you go above 1920x1200 the 4870X2 pretty much owns 5870's @ss as of now.
  • Ryan Smith - Wednesday, September 23, 2009 - link

    For what it's worth, Batman: Arkham Asylum is UE3 engine based.
  • T2k - Wednesday, September 23, 2009 - link

    OK, I missed that (probably because I found the game shots ugly and became uninterested.)
    But how about ET:QW? Yes, it's not the best looking game but it is still popular, let alone World at War which is both great looking and crazy popular, let alone Clear Sky which is a very demanding DX10.1 game? Where is Fallout 3? Where is Modern Warfare?
    FFS the most demanding are the quick ation-shooters and we, FPS players are the first one to upgrade to new cards...
  • Werelds - Thursday, September 24, 2009 - link

    How would ET:QW be a good benchmark? Last I checked, it's still limited to the 30 FPS animations, which makes running it at more than 30 FPS pointless because everything will look jerky.

    I agree something like the CoD games should be included for comparison's sake, but they're hardly a good benchmark or taxing on a system. QW does not fall into the same category though, it has a smaller active playerbase than even L4D which lost a lot of players due to the lack of updates.

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