GTX470/80, Sparse Grid SSAA, DX10+11 done accidentally?

[Sylvanas]

PCgameshardware

User Blaire of the 3D-Center Forum made a sensational discovery: His new SLI setup with three Geforce GTX 480s seemed to display full screen Supersampling Anti-Aliasing (SGSSAA) under DirectX 10 and 11. Some days later more and more evidence became available and thus PC Games Hardware took a look at the matter. Our preliminary conclusion might make some quality oriented gamers really happy: With a GTX 480 or 470 it is possible to apply the best available Anti-Aliasing on the whole image - under DirectX 10 or 11. No other graphics card can do that at the moment - not even AMD's Radeon HD 5000 series which delivers SGSSAA under DirectX 9.

The curious thing about the findings of the 3D Center Forum is that this new effect is caused by a feature that has been available for years: Transparency Anti-Aliasing (TAA). Under DirectX 11/10 the enhanced implementation of the GF100 is applied to the whole scene. If this is done on purpose, has not been clarified yet. We have informed Nvidia and our inquiry has been forwarded to the driver team. As soon as we receive feedback, we will inform you about it.

To me some of the images just look too blurred and I don't see the added benefit- perhaps a LOD adjustment is required. Discuss.

 

[BenSkywalker]

To me some of the images just look blurred

That is the essence of what AA does, the only difference between it and a blur filter is the sampling frequency.

 

[BFG10K]

This is simply fascinating, and awesome.

 

[SirPauly]

Hopefully, you can share some findings at AlienBabelTech.

One of the first clues for this was from this site:

http://www.hardwareluxx.de/index.ph...tx-480-im-test-nvidias-comeback.html?start=28

If one investigates the Battlefield shots in that hardwareluxx link and go back-and-forth -- one can conclude that a full-scene super-sampled was being offered on the textures. Was confused and was trying to find data on why this was happening.

Finally more data from PCgameshardware.

 

[Genx87]

So a driver bug or feature? And what will Nvidia do with the information if they dont already know about it?

 

[BFG10K]

Hopefully, you can share some findings at AlienBabelTech.

I've just put up a blog post right now with some screenshots, and I can confirm this works in OpenGL games, and on Windows XP too. I'll cover IQ in depth in a later article.

Two days ago I noticed performance was lower and transparent textures were getting treated in OpenGL on my GTX470, but I never connected the dots that SSAA was being applied to the whole scene until now.

I have a GTX470 performance article ready to publish, but I now have to go back and check some screenshots in DX9. I have to be absolutely sure this isn’t happening under DX9, because the GTX470 is producing some pretty bad performance compared to my GTX285 overall, and I used TrAA (either SS or MS) in every D3D game I tested.

If this functions in DX9 on XP, this will be an even bigger deal than it is now.

 

[Shilohen]

So a driver bug or feature? And what will Nvidia do with the information if they dont already know about it?

I'd say an involuntary feature. Since it's quite nice, you cannot really qualify it as a bug. However, also since it is quite nice, if it was voluntary, nVidia would have done some PR about it. At any rate, now that this unexpected side effect is known, I wouldn't be surprised to see it added at driver level to a broader range of video cards.

 

[Qbah]

Whoa! This looks really nice. The IQ improvement in that Just Cause 2 screenshot from adding 2xTSSAA is AMAZING!

 

[Lonyo]

So did someone decide to rename FSAA to SSAA? Or is it a different way of doing the same thing?

 

[BenSkywalker]

So did someone decide to rename FSAA to SSAA? Or is it a different way of doing the same thing?

MSAA+AF could be called FSAA accurately. SSAA is a very particular way of doing it(either by rendering the frame multiple times or by rendering it at a higher resolution).

 

[Ryan Smith]

Someone pointed me to this thread, and since I know a thing or two about it, I'll comment.

It's a bug. For Fermi NVIDIA created a new Transparency Super Sampling implementation; they tell me the old one was software based and hence could only work under DX9 while the new one is hardware based and will work on many APIs. Anyhow, their new TrSS implementation isn't supposed to be SSAAing the whole scene, it's only supposed to be SSAAing transparent textures (i.e. fake geometry). In other words it's supposed to behave like their old TrSS implementation on GT200 and lower, except it can work on more than DX9.

As it stands there's an optimization that has yet to be implemented for DX10/DX11 (I didn't ask about OpenGL) that will make it behave correctly. This optimization will be in the Forceware Release 256 drivers, at which point this bug will go away and only transparent textures will be getting SSAAd. Presumably NVIDIA could create a real SSAA mode based on this bug, but I haven't heard anything about them doing so.

The good news is that this means TrSS is going to get a lot faster on Fermi cards on DX10/11, which means it's going to be feasible to have it turned on to resolve the jaggies in games like Crysis and Bad Company 2 (the latter of which I'm personally stoked about, because even with MSAA the jaggies are awful).

http://www.anandtech.com/show/2977/...tx-470-6-months-late-was-it-worth-the-wait-/7

 

[BFG10K]

Now that we've had a taste of what it can do, if nVidia removes it, there’ll be a lot of pissed off people, including myself. The old combined modes are really quite woeful compared to this newer option.

It might be time to start a petition or something to make sure they leave it in as an option.

 

[HurleyBird]

If it is a bug, I'm guessing it would only be a matter of time until a program like rivatuner found a way to reinitialize said bug. This is great news for Nvidia users. Once you get used to the perfectly smooth picture with absolutely NO aliasing ANYWHERE that SSAA gives you, you'll never want to go back

 

[BenSkywalker]

Once you get used to the perfectly smooth picture with absolutely NO aliasing ANYWHERE that SSAA gives you, you'll never want to go back

Unless you don't like the reduced sharpness that SSAA brings to the table. Then you will be more then happy to sprint like hell back to MSAA+AF

 

[SHAQ]

So if you select 2XMSAA and 2X transparency you are really getting 2x2 supersampling? They both have to be set at the same level too I assume? If they do disable it just use Nhancer when the new version comes out or stay with the older drivers.

 

[BFG10K]

Unless you don't like the reduced sharpness that SSAA brings to the table. Then you will be more then happy to sprint like hell back to MSAA+AF

Image quality is absolutely pristine in OpenGL applications, plus you don’t have to deal with ATi’s visible AF transitions. Doom 3 and Prey look simply stunning at 8xSSAA because all surfaces sit perfectly (or almost perfectly) still.

Even without a LOD adjustment, I’d use this all the time in any game that uses shaders and/or alpha textures extensively. In such games, 2xSSAA looks better than 8xS overall, and it runs far faster too. The marginal blurring is a small price to pay for the (near) pixel-perfect rendering you get from it.

 

[BFG10K]

So if you select 2XMSAA and 2X transparency you are really getting 2x2 supersampling?

No, you're getting 2xRGSS in DX10/DX11 and in OpenGL, but not in DX9.

They both have to be set at the same level too I assume?

No, the SSAA is decoupled from MSAA. The only requirement is that TrAA doesn't exceed the base MSAA.

If they do disable it just use Nhancer when the new version comes out or stay with the older drivers.

It won’t work like that. At the moment the driver is “spilling” over the alpha textures and doing the entire scene. The only way nHancer will work is if a hidden debugging setting is left in the driver, or if nVidia decides to officially leave it.

It would be really easy to add officially; just add a third TrAA setting. Call it “full” or something. Then you can get TrMS, TrSS, or full SSAA, depending on which setting you use.

If this is removed it’ll cause an uproar because there’s no good reason to do so, given we know it currently works perfectly. They can leave it unofficially, but removing it completely will really annoy me.

 

[Genx87]

I could see them removing it due to marketing reasons. Reviewers who are not familiar with the setting could turn it on and hurt performance without noting the increase in IQ. Nvidia learned this the hard way with NV30s near flawless AF implementation vs the R300s angle dependent. They got smoked in the reviews due to the performance issue of not using angle dependent AF and rarely got a note on its superior implementation.

I'd think they could still have the ability to turn it on within the driver but have it turned off by default.

/shrug

 

[SHAQ]

They also have SLI AA in the drivers. I don't remember seeing it before. I always had to use Nhancer to enable it. Unfortunately it doesn't work in all games. I got a BSOD in Empire:TW using only enhance AA with 2xTSSAA. Hopefully Nvidia will at least keep it in the driver so Nhancer can enable it. They could just disable it from the control panel.

 

[taltamir]

@SHAQ: what is TSSAA and where did you first hear it? I am compiling a list of AA terms and their explanations (see my signature for link) here on anandtech and would like to know. Thank you.

 

[taltamir]

sorry, i didn't mean to necro. I have figured by now that TSSAA simply means Transparency Super Sampling AA. A name used to refer to the practice of using TrAA to get SSAA on nvidia cards by exploiting this issue. This is based on various other posts, including those on the german forum credited with discovering the phenomenon.

@vivianromen: there is actually a followup to it here: http://www.pcgameshardware.com/aid,...igher-quality-plus-Nvidia-interview/Practice/

turned out it was a bug, but it was popular. So nvidia:
1. fixed it.
2. implemented a proper SSAA (based on it) which it allows enabling via their SSAA tool. They extended it to allow you to selectively apply SSAA to any DX10 or 11 game on fermi, they also added the ability to apply it to any DX9 game using any nvidia card (even ones too slow for it).