4 ms·

> Or at least, you can do that if you still care about MSAA. :) I am a huge fan of all traditional forms of supersampling, intra-frame-only anti-aliasing tech

> Or at least, you can do that if you still care about MSAA. :) I am a huge fan of all traditional forms of supersampling, intra-frame-only anti-aliasing techniques. The performance cost begins to make sense when you realize that these techniques are essentially perfect for the general case. They actually increase the information content of each pixel within each frame. Many modern techniques rely on multiple consecutive frames to build a final result. This is tantamount to game dev quackery in my book. SSAA is even better than MSAA and is effectively what you are using in any game where you can set the "render scale" to a figure above 100%. It doesn't necessarily need to come in big scary powers of two (it used to and made enablement a problem). Even small oversampling rates like 110-130% can make a meaningful difference in my experience. If you can afford to go to 200% scale, you will receive a 4x increase in information content per pixel.

CharlesW 1y ago
I'm a huge fan too, but my understanding is that traditional intra-frame anti-aliasing (SSAA, MSAA, FXAA/SMAA, etc.) does not increase the information capacity of the final image, even though it may appear to do that. For more information per frame, you need one or more of: Higher resolution, higher dynamic range, sampling across time, or multi-sampled shading (i.e. MSAA, but you also run the shader per subsample).
- flohofwoe 1y ago
  MSAA does indeed have a higher information capacity, since the MSAA output surface has a 2x, 4x or 8x higher resolution than the rendering resolution, it's not a 'software post-processing filter' like FXAA or SMAA. The output of a single pixel shader invocation is duplicated 2, 4 or 8 times and written to the MSAA surface through a triangle-edge coverage mask, and once rendering to the MSAA surface has finished, a 'resolve operation' happens which downscale-filters the MSAA surface to the rendering resolution. SSAA (super-sampling AA) is simply rendering to a higher resolution image which is then downscaled to the display resolution, e.g. MSAA invokes the pixel shader once per 'pixel' (yielding multiple coverage-masked samples) and SSAA once per 'sample'.
  - keyringlight 1y ago
    I probably only have a basic understanding of MSAA, but isn't its advantage reduced owing to detail levels even in situations where it could be used. There's so many geometry edges in models and environments (before you consider aspects like tessellation) to AA and intricate shading on plane surfaces so to get a good result you're effectively supersampling much of the image.
- frabert 1y ago
  MSAA actually does, it stores more information per pixel using a special buffer format
  - mikestorrent 1y ago
    What extra information goes in there?
deleted 1y ago
[deleted]
nh23423fefe 1y ago
It can't be 4x increase because the additional information will be correlated and predictable. if i render a linear gradient at increasingly higher resolutions, I certainly am not creating infinite information in the continuum limit obviously
- bob1029 1y ago
  4x is the upper bound. On average across all of gaming the information gain is going to be much more pedestrian, but where the extra information is not predictable it does make a big impact. For some pixels you do get the full 4x increase and those are the exact pixels for which you needed it the most.
  - cma 1y ago
    You still don't get the 4X increase on those pixels. You get it compressed down to a blended by coverage estimation of elements within the pixel. With a 4x higher res display instead of 4x MSAA or 4x SSAA you get more info in that area because you preserve more spatial aspects of the elements of it, instead of just coverage aspects.
    - bob1029 1y ago
      Ok let's try this. In this scenario you have access to a channel with up to 4x more information than what you otherwise would have access to. Exactly how the information is sampled is application specific and will introduce variability into the final result. If we want to get very pedantic, the information gain per pixel could actually be far more dramatic than 4x under any super sampling strategy. Assume a pathological case like a very dark room where 100% render scale doesn't have a single pixel that picks up the edge of a prop in a corner. At higher render scale maybe you start to get a handful of pixels that represent the feature. Even if you blend these poorly, you still get better than nothing. Some might argue that going from zero information to any information at all represents an infinite gain.
      - cma 1y ago
fngjdflmdflg 1y ago
I have always heard that MSAA doesn't work well with deferred rendering which is why it is not longer used[0] which is a shame. Unreal TAA can be good in certain cases but breaks down if both the character and background are in motion, at least from my testing. I wish there was a way to remove certain objects from TAA. I assume this could be done by rendering the frame both with the object and without it there but that seems wasteful. Rendering at a higher resolution seems like a good idea only when you already have a high end card. [0] eg https://docs.nvidia.com/gameworks/content/gameworkslibrary/graphicssamples/d3d_samples/antialiaseddeferredrendering.htm https://docs.nvidia.com/gameworks/content/gameworkslibrary/g...
- TinkersW 1y ago
  MSAA doesn't do anything for shader aliasing, it only handles triangle aliasing, and modern renderers have plenty of shader aliasing so there isn't much reason to use MSAA. The high triangle count of modern renders might in some cases cause the MSAA to become closer to SSAA in terms of cost and memory usage, all for a rather small AA count relative to a temporal method. Temporal AA can handle everything, and is relatively cheap, so it has replaced all the other approaches. I haven't used Unreal TAA, does Unreal not support the various vendor AI driven TAA's?
  - fngjdflmdflg 1y ago
    Unreal has plugins to support other AA including DLSS and FSR (which can both be used just for AA IIRC). I tried FSR and it didn't work as well as the default TAA for certain cases, but I'm pretty sure I just had some flickering issue in my project that I was trying to use TAA to solve as a band aid so maybe not a great example of which AA methods are good. I'm not an expert and only use Unreal in my spare time.
  - charcircuit 1y ago
    >Temporal AA can handle everything With the tradeoff of producing a blurry mess.
    - 1y ago
perching_aix 1y ago
Aren't some forms of aliasing specifically temporal in nature? For example, high detail density induced flicker on movement. I appreciate people standing up for classical stuff, but I don't want the pendulum swung too far back the other way either.
- Sohcahtoa82 1y ago
  That flickering is heavily reduced already by mipmapping and anisotropic filtering.
Pannoniae 1y ago
Yeah, and we can actually afford to do it nowadays. I'm currently making a game with very retro graphics (think Minecraft-level pixelated stuff) Sure, the textures themselves aren't too high fidelity, but since the pixel shader is so simple, it's quite feasible to do tricks which would be impossible even ten years ago. I can run the game even with 8x SSAA (that means 8x8=64 samples per pixel) and almost ground truth, 128x anisotropic filtering. There's practically zero temporal aliasing and zero spatial aliasing.[0] Now of course, some people don't like the lack of aliasing too much - probably conditioning because of all the badly running, soulless releases - but I think that this direction is the future of gaming. Less photorealism, more intentional graphics design and crisp rendering. (edit: swapped the URL because imgur was compressing the image to shit) [0] https://files.catbox.moe/46ih7b.png https://files.catbox.moe/46ih7b.png
thunderfork 1y ago
Not that I don't agree emotionally on how much better single-frame rendering is than multi-frame on a spiritual level... I do find the whole "game dev quackery" thing kind of a funny perspective? Real-time graphics is all about tricks and fakery, and it's been that way since we've been racing the beam. Did people think that deferred rendering was a dirty trick when those Shrek devs figured it out and everyone stopped doing forward rendering?

CharlesW 1y ago

I'm a huge fan too, but my understanding is that traditional intra-frame anti-aliasing (SSAA, MSAA, FXAA/SMAA, etc.) does not increase the information capacity of the final image, even though it may appear to do that. For more information per frame, you need one or more of: Higher resolution, higher dynamic range, sampling across time, or multi-sampled shading (i.e. MSAA, but you also run the shader per subsample).

flohofwoe 1y ago
MSAA does indeed have a higher information capacity, since the MSAA output surface has a 2x, 4x or 8x higher resolution than the rendering resolution, it's not a 'software post-processing filter' like FXAA or SMAA. The output of a single pixel shader invocation is duplicated 2, 4 or 8 times and written to the MSAA surface through a triangle-edge coverage mask, and once rendering to the MSAA surface has finished, a 'resolve operation' happens which downscale-filters the MSAA surface to the rendering resolution. SSAA (super-sampling AA) is simply rendering to a higher resolution image which is then downscaled to the display resolution, e.g. MSAA invokes the pixel shader once per 'pixel' (yielding multiple coverage-masked samples) and SSAA once per 'sample'.
- keyringlight 1y ago
  I probably only have a basic understanding of MSAA, but isn't its advantage reduced owing to detail levels even in situations where it could be used. There's so many geometry edges in models and environments (before you consider aspects like tessellation) to AA and intricate shading on plane surfaces so to get a good result you're effectively supersampling much of the image.
frabert 1y ago
MSAA actually does, it stores more information per pixel using a special buffer format
- mikestorrent 1y ago
  What extra information goes in there?

deleted 1y ago

[deleted]

nh23423fefe 1y ago

It can't be 4x increase because the additional information will be correlated and predictable. if i render a linear gradient at increasingly higher resolutions, I certainly am not creating infinite information in the continuum limit obviously

bob1029 1y ago
4x is the upper bound. On average across all of gaming the information gain is going to be much more pedestrian, but where the extra information is not predictable it does make a big impact. For some pixels you do get the full 4x increase and those are the exact pixels for which you needed it the most.
- cma 1y ago
  You still don't get the 4X increase on those pixels. You get it compressed down to a blended by coverage estimation of elements within the pixel. With a 4x higher res display instead of 4x MSAA or 4x SSAA you get more info in that area because you preserve more spatial aspects of the elements of it, instead of just coverage aspects.
  - bob1029 1y ago
    Ok let's try this. In this scenario you have access to a channel with up to 4x more information than what you otherwise would have access to. Exactly how the information is sampled is application specific and will introduce variability into the final result. If we want to get very pedantic, the information gain per pixel could actually be far more dramatic than 4x under any super sampling strategy. Assume a pathological case like a very dark room where 100% render scale doesn't have a single pixel that picks up the edge of a prop in a corner. At higher render scale maybe you start to get a handful of pixels that represent the feature. Even if you blend these poorly, you still get better than nothing. Some might argue that going from zero information to any information at all represents an infinite gain.
    - cma 1y ago

fngjdflmdflg 1y ago

I have always heard that MSAA doesn't work well with deferred rendering which is why it is not longer used[0] which is a shame. Unreal TAA can be good in certain cases but breaks down if both the character and background are in motion, at least from my testing. I wish there was a way to remove certain objects from TAA. I assume this could be done by rendering the frame both with the object and without it there but that seems wasteful. Rendering at a higher resolution seems like a good idea only when you already have a high end card. [0] eg https://docs.nvidia.com/gameworks/content/gameworkslibrary/graphicssamples/d3d_samples/antialiaseddeferredrendering.htm https://docs.nvidia.com/gameworks/content/gameworkslibrary/g...

TinkersW 1y ago
MSAA doesn't do anything for shader aliasing, it only handles triangle aliasing, and modern renderers have plenty of shader aliasing so there isn't much reason to use MSAA. The high triangle count of modern renders might in some cases cause the MSAA to become closer to SSAA in terms of cost and memory usage, all for a rather small AA count relative to a temporal method. Temporal AA can handle everything, and is relatively cheap, so it has replaced all the other approaches. I haven't used Unreal TAA, does Unreal not support the various vendor AI driven TAA's?
- fngjdflmdflg 1y ago
  Unreal has plugins to support other AA including DLSS and FSR (which can both be used just for AA IIRC). I tried FSR and it didn't work as well as the default TAA for certain cases, but I'm pretty sure I just had some flickering issue in my project that I was trying to use TAA to solve as a band aid so maybe not a great example of which AA methods are good. I'm not an expert and only use Unreal in my spare time.
- charcircuit 1y ago
  >Temporal AA can handle everything With the tradeoff of producing a blurry mess.
  - 1y ago

perching_aix 1y ago

Aren't some forms of aliasing specifically temporal in nature? For example, high detail density induced flicker on movement. I appreciate people standing up for classical stuff, but I don't want the pendulum swung too far back the other way either.

Sohcahtoa82 1y ago
That flickering is heavily reduced already by mipmapping and anisotropic filtering.

Pannoniae 1y ago

Yeah, and we can actually afford to do it nowadays. I'm currently making a game with very retro graphics (think Minecraft-level pixelated stuff) Sure, the textures themselves aren't too high fidelity, but since the pixel shader is so simple, it's quite feasible to do tricks which would be impossible even ten years ago. I can run the game even with 8x SSAA (that means 8x8=64 samples per pixel) and almost ground truth, 128x anisotropic filtering. There's practically zero temporal aliasing and zero spatial aliasing.[0] Now of course, some people don't like the lack of aliasing too much - probably conditioning because of all the badly running, soulless releases - but I think that this direction is the future of gaming. Less photorealism, more intentional graphics design and crisp rendering. (edit: swapped the URL because imgur was compressing the image to shit) [0] https://files.catbox.moe/46ih7b.png https://files.catbox.moe/46ih7b.png

thunderfork 1y ago

Not that I don't agree emotionally on how much better single-frame rendering is than multi-frame on a spiritual level... I do find the whole "game dev quackery" thing kind of a funny perspective? Real-time graphics is all about tricks and fakery, and it's been that way since we've been racing the beam. Did people think that deferred rendering was a dirty trick when those Shrek devs figured it out and everyone stopped doing forward rendering?