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Question about anti-aliasing

By yRaz ยท 5 replies
Jun 17, 2011
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  1. In the nVidia control panel I've noticed 2 different AA settings. There is the normal option then transparency AA. I'm almost certain transparency AA is SSAA, which, as I understand it, is rendering a larger image and shrinking it down opposed to CSAA and MSAA that only select edges.

    Just for fun I turned on 32X CSAA and 8X SSAA and loaded up crysis 1.
    The question:
    When using 32X CSAA with 8XSSAA is that effectively 256X AA?
  2. dividebyzero

    dividebyzero trainee n00b Posts: 4,891   +1,262

    Transparency AA can be applied to SuperSampling (TrSSAA) or MultiSampling (TrMSAA)
    Your understanding of Super Sampling is correct. It increases the natural resolution by 2 or 4 times the original for the whole screen (hence Full Screen AA or FSAA) and is then down sampled. MSAA is basically as you pointed out, polygon edge AA, while Coverage Sample AA (CSAA) is basically extends MSAA with less sampling of shaders and textures while applying coverage samples to polygons (at a higher resolution) to sample the whole rendered image.

    Transparency AA detects transparent/opaque textures and re-samples those over the chosen AA (SSAA/MSAA) used.

    Just for fun....
    If you use Nvidia Inspector you can also choose Sparse Grid Super Sampling AA (SGSSAA) on enthusiast grade cards (the only ones that will handle the setting more often than not). SGSSAA renders the whole image/scene with Super Sampling but with a lower number of samples. Not all games support SGSSAA as it can conflict with some post processing effects. You may also want to effect a negative LOD (quick instructional here)

    Nope, thats just wishful thinking.
    Here's a chart with some of the more readily applied AA modes...
    The columns are set out in order of computational complexity. Shaders being the most intensive, coverage being the least.

    You probably wished you'd never asked :D
  3. yRaz

    yRaz TS Evangelist Topic Starter Posts: 2,146   +1,222

    Thank you, that was very informative and a good read. I have a gtx 460 1gb and it is highly overclocked(950/1900/2000). However, I don't see my AA combo in that chart. I do have to say all my games looks effing amazing at @1080p even if it is running at .2FPS lol.
  4. dividebyzero

    dividebyzero trainee n00b Posts: 4,891   +1,262

    For 8xTrSSAA+32xCSAA

    Shader- Texture-Colour-Depth- Z Stencil-Coverage
    8...........8..........8..........8...........8.............32..............in theory. This Tom's Hardware report on control panel forced AA modes shows that the forcing is rather hit-and-miss and heavily application dependant (page 7 of the article).

    BTW: 32 x (pure) SSAA is the highest level of anti aliasing that can be achieved with the present single GPU Nvidia cards. 2 x 32 (64) x SSAA is available for SLI mode (GTX 590 and SLI'ed single cards), 3 x 32 (96) x SSAA for tri-SLI and 4 x 32 (128) x SSAA for quad-SLI
  5. yRaz

    yRaz TS Evangelist Topic Starter Posts: 2,146   +1,222

    That's a selling point on an SLi rig right there lolololololol. Just about any game can be made to look better using enough aliasing. I've noticed that 8xSSAA makes the textures in older games look a lot smoother. so, is 64X only available on the 500 series? I'd pick up another 460 in a heart beat if that was the case.
  6. dividebyzero

    dividebyzero trainee n00b Posts: 4,891   +1,262

    I'm pretty sure the higher modes are GTX470/480/570/580/590 only at this point. What effectively happens is that each GPU processes half the desired AA level (i.e. for SLI 64xQ each card renders at 2x Full Screen MSAA + 32xQ CSAA).

    SLI AA is still available to any SLI'ed graphics, and comes in handy where the game is framerate capped- so that you can raise AA without a serious performance penalty. For most games going better than 4 or 8x MSAA (or equivalent) is going to be a severe case of diminishing returns image quality wise, so having each GPU process at 2 or 4xMSAA will net a substantial gain in game i.q. without too much of a f.p.s. drop. I think Tom's Hardware is supposed to be publishing a follow-up article to the one in the link I posted- hopefully it encompasses SLI/CrossfireX AA scaling...and very hopefully, use of third party tweak apps like Nvidia Inspector and nHancer.

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