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Anti-Aliasing Analysis, Part 1: Settings And Surprises

Anti-Aliasing Analysis, Part 1: Settings And Surprises
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Some time has passed since we last delved into the state of anti-aliasing. In this article, we investigate the feature thoroughly from the basics to vendor-specific implementations and learn some shocking surprises about driver settings along the way.

What is anti-aliasing? The prefix “anti” can be defined as counteracting or neutralizing, and “aliasing” is a jagged, stair-step effect on curved or diagonal lines. Therefore, anti-aliasing means to counteract and neutralize jagged lines. When it comes to PC graphics technology, we usually refer to anti-aliasing as it pertains to 3D gaming—it’s a feature that our video cards offer to make graphics appear more attractive.

The concept sounds simple enough. But unfortunately, anti-aliasing isn’t turned on with a simple switch. Today’s video hardware offers a wide variety of options that can be used in 30 or more combinations, depending on the card you own. What does each setting change? What are the advantages and disadvantages of each option? Which ones should you enable or leave alone?

We’re going to do our best to clear up the confusion with this comprehensive anti-aliasing guide. Starting with a short recap of the basics, we move onto generic methods and then vendor-specific implementations. We show you where you can set the options, and give you examples of what those options look like as you play your favorite games. And we'll be following this informational article up in the next couple of weeks with part two, an in-depth numbers-based comparison that will demonstrate the level of anti-aliasing performance you can expect from a wide variety of graphics cards.

Anti-Aliasing Basics

Anti-aliasing has been around for some time and many of our readers already understand the concept. In an article like this, though, it’s important to start from the very beginning. Folks well-acquainted with the fundamentals can think of this page as a brief refresher.

As always, with graphics, we must start with the pixel. Pixels are the little square dots that make up an image on a computer screen, the smallest addressable element. Aliasing is a byproduct of using square dots to display an image. Consider a picture of a black diagonal line over a white background:

As you can see—especially when zoomed in—the nature of pixels creates a stair-stepping effect, which is called aliasing. Here’s what it looks like in a PC game:

See how the pixels on the edge of objects now blend in with the color behind when anti-aliasing is enabled? Anti-aliasing makes edges appear smoother and less pixilated by blending the color of the edge and the background.

Note that stair-stepping appears more prominently at lower resolutions because there are fewer pixels with which to display the image.

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  • -4 Hide
    atikkur , April 13, 2011 4:19 AM
    PERTAMAX gan. .
  • 8 Hide
    burnley14 , April 13, 2011 4:24 AM
    Awesome article. I am unfortunately not one of the elite few who know all the ins and outs of graphics performance, so this was very enlightening for me.
  • 4 Hide
    dragonsqrrl , April 13, 2011 5:28 AM
    Great article, very informative. I've never really used forced anti-aliasing through the driver, and from what I've read it doesn't really sound like a good idea anyway, given the fact that most modern games provide adequate AA levels through in-game settings (these are usually better optimized as well). Seems like forced driver level AA is pretty hit-or-miss. With a few rare exceptions it just doesn't seem like it's worth the effort.

    ...went to the link for Tom's Geforce3 article. The good old Geforce3, now that takes me back.
  • 8 Hide
    tallguy1618 , April 13, 2011 5:36 AM
    This is definitely one of the better articles I've read
  • 0 Hide
    Anonymous , April 13, 2011 6:37 AM
    what are you talking about?
    we can still force Supersampling
    as of 266.58 on Nvidia cards
  • 1 Hide
    army_ant7 , April 13, 2011 7:00 AM
    Why does it say here, http://www.geforce.com/#/Optimize/Guides/AA-AF-guide (go to the next page of this article), that it internally renders the frame at a resolution 4 times greater? But according to the 2nd page of this article, it says that at x4 AA it only internally renders a frame at a resolution 2 times greater.
  • 3 Hide
    JimmiG , April 13, 2011 7:23 AM
    Great article, but this is really something Nvidia and AMD will have to fix together with game developers...

    The settings I select in the driver control panel should apply without me having to worry about coverage samples, multi samples, DirectX versions or the alignment of the planets. It should just work.

    Similarly, any self-respecting game made in the last 6-8 years should have proper anti-aliasing options in its in-game menu. Not just an On/Off switch, but the full range of AA settings available with the video card being used.
  • -1 Hide
    BulkZerker , April 13, 2011 7:24 AM
    MrBonkBonkwhat are you talking about?we can still force Supersampling as of 266.58 on Nvidia cards



    IF the game lets it! Drivers trying to force AA doens't mean the game will allow it. If the game doesnt' support it your not goting to get tehy type of AA.

    Either way this AA fragmentation is almost as bad as all these custom versions of Driod.
  • 1 Hide
    Assmar , April 13, 2011 7:24 AM
    Maybe I'm wrong, but no Batman or Mass Effect 2 forced AA settings?
  • 2 Hide
    heycarnut , April 13, 2011 7:29 AM
    @army_ant7:

    Nvidia article is wrong, or at the very least semantically sloppy.

    4X samples generally means doubling of resolution for both axes. 4*(x*y)==(2*x)*(2*y).
  • 1 Hide
    army_ant7 , April 13, 2011 7:33 AM
    Quote:
    Nvidia article is wrong, or at the very least semantically sloppy.

    4X samples generally means doubling of resolution for both axes. 4*(x*y)==(2*x)*(2*y).


    Thanks for the reply heycarnut.

    With that it mind, what does 2X sampling multiply the axes by?
  • 0 Hide
    nileshd , April 13, 2011 7:43 AM
    if the game doesn't support anti aliasing, forcing through the driver may or may not work, but the point here is that nvidia drivers still do support supersampling as opposed to that mentioned in the article.
  • 0 Hide
    mattmock , April 13, 2011 9:25 AM
    Nvidia is currently offering a SSAA tool for download. Its a bit primitive and just sets SSAA for all games.
    http://nvidia.custhelp.com/cgi-bin/nvidia.cfg/php/enduser/std_adp.php?p_faqid=2624
  • 0 Hide
    tavix , April 13, 2011 10:48 AM
    Gr8 article. Thanks!
  • 0 Hide
    ghostie , April 13, 2011 11:11 AM
    Thanks for the great article Don.
  • 0 Hide
    rpgplayer , April 13, 2011 11:22 AM
    how about some benchmarks with the games that accepted forced driver settings? that way we can see if the in game setting is biased toward one card company. like left for dead 2, benchmarks of the ingame setting for 2x,4x,8x. then benchmarks of the driver setting 2x MSAA/SSAA, 4x MSAA/SSAA and so on. that way we can see if the game is being biased.
  • 0 Hide
    feeddagoat , April 13, 2011 1:17 PM
    Ive always wondered what was the difference between and what was better between application decided and driver based AA. In far cry 2 using my HD4870 The trees turned into green blobs using driver based AA but in game AA worked perfectly. Since then Ive just left the let the application decide box ticked and ignored Driver based. Can't wait for part 2 to see what gives the best result if it even works. Great work toms!!
  • 2 Hide
    warhammerkid , April 13, 2011 1:20 PM
    Nvidia Inspector (http://blog.orbmu2k.de/tools/nvidia-inspector-tool) is like the Nvidia control panel on steroids. It gives access to many more of the configuration options than the Nvidia control panel, like SSAA, several settings for transparency anti-aliasing, and a whole bunch of other advanced configuration options. I prefer it over nHancer (http://www.nhancer.com/), as I've had better luck with it in the past, but both should work. I'm somewhat surprised, though, that no one at Tom's Hardware actually used it to test out Nvidia SSAA, as I've had quite a lot of success with it.

    assmarMaybe I'm wrong, but no Batman or Mass Effect 2 forced AA settings?

    I used Nvidia Inspector on Mass Effect 1 and Mass Effect 2 to play the game with 2x2 SSAA (2x horizontal and 2x vertical), and it definitely works if you set it to force the game to use those settings. Forcing MSAA in those games didn't seem to work though, or if it did the effect wasn't noticeable enough to be worth it, not surprising considering some of the issues Unreal Engine games have with anti-aliasing. I didn't bother trying this with Batman because the built-in AA for the game looked fine.
  • 0 Hide
    WyomingKnott , April 13, 2011 2:01 PM
    I can see the benefit from AA in the examples, but doesn't it make things look fuzzy? I suppose it's a necessary trade-off for now.
  • 1 Hide
    cleeve , April 13, 2011 2:44 PM
    army_ant7Why does it say here, http://www.geforce.com/#/Optimize/Guides/AA-AF-guide (go to the next page of this article), that it internally renders the frame at a resolution 4 times greater? But according to the 2nd page of this article, it says that at x4 AA it only internally renders a frame at a resolution 2 times greater.


    Depends on how you frame it I guess: when the dimensions are doubled, the area is quadrupled.

    Twice the size is four times the samples: Like a 2"x2" grid contains four square inches, and twice the size is 4"x4" but it contains 16 square inches... four times as much area, but only twice the size when you look at the dimensions.

    army_ant7With that it mind, what does 2X sampling multiply the axes by?


    1.5 times? :p 

    It's probably easier to just think of the number as how many samples per pixel. 2xAA=2 samples per pixel, 4xAA=4 samples per pixel, etc...
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