Alternative AA methods and their comparison with traditional MSAA*

Discussion in 'Rendering Technology and APIs' started by mitran, Nov 15, 2009.

  1. TheAlSpark

    TheAlSpark Moderator
    Moderator Legend

    Joined:
    Feb 29, 2004
    Messages:
    22,146
    Likes Received:
    8,533
    Location:
    ಠ_ಠ
    Well, it's better than the FXAA stuff in Skyrim, plus it's on 360. :s
     
  2. Andrew Lauritzen

    Andrew Lauritzen Moderator
    Moderator Veteran

    Joined:
    May 21, 2004
    Messages:
    2,554
    Likes Received:
    642
    Location:
    British Columbia, Canada
    Oh I'm not being negative... I'm actually curious. The only pessimistic overtone I was conveying is just more of people concluding stuff ("crawling/sub pixel problems are not as pronounced as in other types of post process AA techniques") without actually comparing them on the same assets/game. The two are not independent.
     
    #1142 Andrew Lauritzen, Nov 20, 2011
    Last edited by a moderator: Nov 20, 2011
  3. MJP

    MJP
    Regular

    Joined:
    Feb 21, 2007
    Messages:
    566
    Likes Received:
    187
    Location:
    Irvine, CA
    I haven't seen the game in person, but based on the description it sounds like they used an existing post process AA solution and tweaked it to only be applied on geometry edges (probably using depth, normal, or even material discontinuities).
     
  4. TheAlSpark

    TheAlSpark Moderator
    Moderator Legend

    Joined:
    Feb 29, 2004
    Messages:
    22,146
    Likes Received:
    8,533
    Location:
    ಠ_ಠ
    Wondered if maybe it was Jimenez MLAA or something. *shrug*

    Anyways, the Edge Detection does look quite a bit better than anything else I've seen so far on the console, so maybe they use depth afterall. (wonder if they had to access/use depth anyway for doing the 3D mode so the cost was already considered?)


    Oh, I have no clue about the sub-pixel crawling thing. I just know about the filtering. :p
     
  5. Ruskie

    Veteran

    Joined:
    Mar 7, 2010
    Messages:
    1,291
    Likes Received:
    1
    I don't know about crawling either, thats what DF wrote. I have game on my 360 and it does look very smooth. Beta on PS3 on the other hand was actually jaggier and blurrier, they probably tweaked it.

    http://i.imgur.com/ziZWp.jpg
     
  6. IrYoKu

    Newcomer

    Joined:
    Sep 28, 2010
    Messages:
    12
    Likes Received:
    0
    Location:
    Zaragoza
    We tried to leverage the subsample information in various ways.

    The first thing we tried is applying MLAA on top of a resolved image. Unfortunately, this didn't work. Edge detection fails as the edges have much less contrast after the resolve; furthermore, even if you run the edge detection pass on top of the original unresolved data, the coverage areas used for blending will not produce the correct values (as the pixels are already blended by the 2x resolve). We tried to bias this in various ways, but we came to the conclusion that it's impossible to do it in a general way. Here you have what happens if you do MLAA after resolving:

    http://www.flickr.com/photos/70160915@N03/6373855775/

    Then, we tried to apply MLAA before resolving. It worked better, but it was still performing worse than MSAA for the same sample count, with regards to subpixel features (see MLAA + 4x):

    http://www.flickr.com/photos/70160915@N03/6373890101/

    This is because of two main reasons. The first one is that MLAA tends to round everything at subpixel level. This means that MSAA or SSAA won't be able to correctly resolve into the proper values. The second reason is that MLAA assumes the revectorization to be centered in the pixel (MLAA or any other postprocessing AA). However, when supersampling or multisampling MLAA, this revectorization must be moved to the center of the sampling pattern:

    http://www.flickr.com/photos/70160915@N03/6373856415/

    The problem is that if we don't do this, areas will be over/understimated, causing objects to glow. Furthermore, applying MLAA with MSAA will never converge to MSAA despite using really high sample counts.

    Other option we tried is running MLAA at subpixel level; however, postprocessing antialiasing does not work well with rotated grid patterns, which rules out any MSAA approach.

    It could be used for rendering antialiased hard shadows if used in tandem with VSM or ESM (as regular shadow mapping cannot be prefiltered). For soft shadow mapping I think it would be less useful because the blurring gets rid of aliasing anyway.

    Agreed; actually, it's easy to find these scenarios by playing with our demo. We think that mixing MLAA, MSAA and temporal SSAA into a single technique is a good approach because it offers fallbacks in these kind of failure scenarios.

    This is actually a problem of our MLAA approach on that console. Half of the time is spent on resolves. We've various ideas to improve things on consoles, we hope to get a devkit soon to try them!

    We like doing the edge detection step on the motion blur pass, because this way you can skip pixels that will receive a lot of motion blur. And also because the neighbors will probably be in the texture cache (as you mentioned), it will add little overhead.

    Regarding Assasins Creed Revelations AA, it looks really nice indeed!
     
  7. Andrew Lauritzen

    Andrew Lauritzen Moderator
    Moderator Veteran

    Joined:
    May 21, 2004
    Messages:
    2,554
    Likes Received:
    642
    Location:
    British Columbia, Canada
    Lots of good information! Thanks for taking the time to explain that all and show pictures. I think I understand your technique, and more importantly the reasoning by which you arrived at it, better now :) I agree with your conclusion as well... we need to use a combination of several AA techniques to get an efficient, high-quality solution.
     
  8. Man from Atlantis

    Regular

    Joined:
    Jul 31, 2010
    Messages:
    928
    Likes Received:
    767
    I'm glad to present you Inject SMAA by mrhaandi :)

    This is only SMAAx1.. i hope he will enhance it further..


    NoAA

    Inject FXAA

    Inject SMAA
     
    #1148 Man from Atlantis, Nov 29, 2011
    Last edited by a moderator: Nov 30, 2011
  9. homerdog

    homerdog donator of the year
    Legend Veteran Subscriber

    Joined:
    Jul 25, 2008
    Messages:
    6,294
    Likes Received:
    1,075
    Location:
    still camping with a mauler
    FXAA looks better? There's some heavy jpg compression going on there so it's hard to tell. I hope he enables the higher quality modes at some point.
     
  10. Ethatron

    Regular Subscriber

    Joined:
    Jan 24, 2010
    Messages:
    941
    Likes Received:
    400
    Actually it doesn't, look at the thin branches of the tree, FXAA smears it all over.
     
  11. homerdog

    homerdog donator of the year
    Legend Veteran Subscriber

    Joined:
    Jul 25, 2008
    Messages:
    6,294
    Likes Received:
    1,075
    Location:
    still camping with a mauler
    It's not really worth arguing over. FXAA looks better IMO, but that isn't going to take the discussion very far.
     
  12. snarfbot

    Regular Newcomer

    Joined:
    Apr 23, 2007
    Messages:
    652
    Likes Received:
    225
    looks pretty darn good to me, heres a cap of dead space with it.

    smaa
    [​IMG]

    fxaa
    [​IMG]

    honestly i cant tell the difference when im playing, but the smaa does look a bit better in screen caps.

    thanks atlantis.
     
  13. doob

    Regular

    Joined:
    May 21, 2005
    Messages:
    392
    Likes Received:
    4
    I'd prefer it over the other 2 fxaa injectors that were released/repacked with the sharp(and other) filter(s) *edit* if it had them as well*edit*. As i personally prefer to keep the post-aa blur(and bloom) toned down(but with high precision values, focusing mostly on contrast) while giving priority to crisper/sharp textures, it can do wonders in some games as small details (and/or patterns) become more vivid and less muddy/smudged.

    Untill then i'll just keep an eye on smaa as a potencial replacement.
     
    #1153 doob, Nov 30, 2011
    Last edited by a moderator: Nov 30, 2011
  14. Man from Atlantis

    Regular

    Joined:
    Jul 31, 2010
    Messages:
    928
    Likes Received:
    767
  15. fellix

    Veteran

    Joined:
    Dec 4, 2004
    Messages:
    3,534
    Likes Received:
    495
    Location:
    Varna, Bulgaria
    SMAA definitely handles GUI elements better.
     
  16. homerdog

    homerdog donator of the year
    Legend Veteran Subscriber

    Joined:
    Jul 25, 2008
    Messages:
    6,294
    Likes Received:
    1,075
    Location:
    still camping with a mauler
    I can't tell much difference between FXAA and SMAA TBH. I'll have to study these screenies some more. :smile:

    BTW Skyrim supports a very technologically advanced AA mode called MSAA that looks better than FXAA and SMAA and is basically free on modern GPUs. I don't know how they managed to pull it off, must be geniuses or something.
     
  17. Deadly Towers

    Newcomer

    Joined:
    Nov 25, 2004
    Messages:
    24
    Likes Received:
    0
    SMAA gives smother diagonal edges; it's not as crawly in motion.

    Skyrim has some effects that break MSAA, so the multisample version of SMAA would be a good approach there.
     
  18. KKRT

    Veteran

    Joined:
    Aug 10, 2009
    Messages:
    1,040
    Likes Received:
    0
    If only MSAA was good enough for Skyrim ;\ and i wish it was free ;p I'll need to test, if it gives me better results with 1.5x1.5 OGSSAA in Skyrim in comparison to 4xMSAA.
     
  19. Man from Atlantis

    Regular

    Joined:
    Jul 31, 2010
    Messages:
    928
    Likes Received:
    767
    a little more blur could help especially in Mass Effect 2 and Dragon Age 2.. looks better with FXAA..
     
  20. homerdog

    homerdog donator of the year
    Legend Veteran Subscriber

    Joined:
    Jul 25, 2008
    Messages:
    6,294
    Likes Received:
    1,075
    Location:
    still camping with a mauler
    Considering even my GTX260 can hold 60fps with 4xMSAA I'd call it free. You'll be CPU limited in this game unless you have a very weak GPU or are doing some crazy supersampling (which I guess you are..).

    I use 4xMSAA + FXAA and the IQ is very nice. There are no jaggies to be found anywhere; the only aliasing I see is related to specular highlights and transparencies.
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...