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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  • JonnyDough - Wednesday, September 23, 2009 - link

    They could probably use a 1.5 GB card. :(
  • yacoub - Wednesday, September 23, 2009 - link

    why is the 5870 so freaking LONG??

    I'm pretty sure you could land aircraft on it.

    http://images.anandtech.com/reviews/video/ATI/5870...">http://images.anandtech.com/reviews/video/ATI/5870...
    Someone should photoshop a person into that image for scale. They'd be standing in the shadow underneath the PCIe connector, waving at you, and there would be an F-35 JSF circling like a fly trying to land on the deck.
  • Ryan Smith - Wednesday, September 23, 2009 - link

    It's your standard, full-length 10.5" card. It's the same as the GTX cards and the 4870X2

    Here's a shot comparing it to a GTX 285 and a 4890 that I didn't get to use in the article.

    http://images.anandtech.com/reviews/video/ATI/5870...">http://images.anandtech.com/reviews/video/ATI/5870...
  • SiliconDoc - Monday, September 28, 2009 - link

    If you can't see the 5870 is the longest card in that pic, then you've got different problems than just lying issues.
    Another one, another big fat fib, with pic included, that proves the fib to be a fab fib.
    It's amazing.
    ---
    "No, everyone, do not believe your lying eyes, it's a standard 10.5" measured in the new red rooster barnyard stick."

    Cripes call International Weights and Measures, we have warped space time around the new ati card it's so powerful.
  • LSnK - Wednesday, September 23, 2009 - link

    Or plainly spoken, angle independent angle-dependent filtering. How confusing.
  • frozentundra123456 - Wednesday, September 23, 2009 - link

    Mildly disappointed in the initial results for this card. It is powerful,admittedly, but it has less than twice the performance of the 4870. Also does not use less power. Maybe I was expecting too much. It surely is not a giant step up like the introduction of the 4xxx series cards. I was hoping for another big leap in performance per watt.

    I have a feeling that nVidia's 300 series will beat it when it finally comes out, although hopefully ATI will still be ahead in performance per watt and performance per dollar.
    I hope they make a good low/midrange card like the 4670 that does not require external power but has increased performance.
  • Spoelie - Wednesday, September 23, 2009 - link

    I reckon you'll see performance improve the coming months, as ATi's compiler improves to use the new instructions more efficiently. The card you see here today will not be the one fighting GT300.

    Granted, it won't make huge strides, but I guesstimate it to be 5-10% better, depending on circumstance/game, by the november-january timeframe (when GT300 hopefully lands).

    Nvidia's baby will probably still be faster, but if the margin turns out to be slim, we'll have another rv770 vs GT200 situation playing out. And when the first wave of DX11 games have hit, somewhere next year, it'll be time to reevaluate again ;).
  • JonnyDough - Wednesday, September 23, 2009 - link

    and I stopped. I had to post this:

    "Sometimes a surprise is nice. Other times it’s nice for things to go as planned for once.

    Compared to the HD 4800 series launch, AMD’s launch of the HD 5800 series today is going to fall in to the latter category. There are no last-minute announcements or pricing games, or NDAs that get rolled back unexpectedly. Today’s launch is about as normal as a new GPU launch can get."

    If it's normal for all that crap to happen, wouldn't it be ABNORMAL for AMD to have a great launch? :)
  • SiliconDoc - Wednesday, September 23, 2009 - link

    LOL
    " . Today’s launch is about as normal as a new GPU launch can get."
    I guess he meant "for reviewers" - since the "normal launch" today is "listed on the websites for sale, but greyed out, not available, or pre-order" - meaning NO STOCK.
    ---
    Yehah buddy, that is a "as normal as any launch" so long as it's the immensely favored ATI launching, and not that hated greedy Nvidia...
    A normal launch and you can't buy the card...rofl.
  • JonnyDough - Thursday, September 24, 2009 - link

    I wasn't being a fanboi, merely mocking normal launches from several companies. Seems like paper launches almost became the norm for awhile. :P

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