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burningrave101
07-08-04, 10:18 AM
I'm curious what everyones opinion is about how ATI gets such better AF performance on their X800's.

Cause when your not using AF at all the 6800u and 6800GT is always ahead of the X800XT PE and X800Pro and the 6800's only have small performance losses when enabling 4xAA so their always in the lead there as well, but when you enable like 16xAF its all the 6800's can do to keep up.

http://www.hothardware.com/viewarticle.cfm?page=3&articleid=550&cid=2

You can clearly see from those benches that the X800Pro is hardly competing against the GT until 16xAF was enabled.

Whats the deal? Is ATI optimizing their AF to hell and back somewhow? Is it because their using a Brilinear filtering trick like nVidia did with their NV30's???

I wanna know some facts :p.

Here is the information i've gathered so far.

Actually to do it correctly on ATI hardware, both the AA & AF are set in-game, not thru the control panel. Setting AF thru the control panel gets you additional performance but lower IQ as Trilinear filtering is only done on the first stage. When possible, always set your AF in-game on ATI hardware. I don't think it should matter on AA though. If everyone sets their aa & af in-game nothing is left to speculation as both are being applied the way the game designer wanted it, not the way Nvidia or ATI decided.

http://www.nvnews.net/vbulletin/showthread.php?t=31421&page=4

Conclusion

All Filter optimizations discussed here aim to increase the performance of the graphics cards without materially reducing image quality. The word "materially" is, however, subjective - depending on the optimization used, a loss in quality is perceptible when taking a closer look. Even if the quality in screenshots is OK, a running game is often a different chapter. Annoying effects (moiré, flickering) can crop up that were not noticeable on screenshots.

In the case of graphics cards in the medium and lower price segment, the customer will certainly get added value in the filter optimizations, because "correct" filtering would slow the chips down too much. The user can play in higher resolutions or add filter effects that without the optimizations would be unplayable. The bottom line is that the customer ends up with better image quality.

It's a different story with the new enthusiast cards, such as the Radeon X800 Pro/XT and the GeForce 6800 Ultra/GT. With those cards the optimizations do not provide the customer with new added value - on the contrary. He gets a reduced image quality, although the card would actually be fast enough to deliver maximum quality at what would surely still be an excellent frame rate. We cannot escape the impression that the filter optimizations in the new top models will no longer be used ultimately to offer the customer added value, but rather solely in order to beat the competition in the benchmark tables, which are so important in the prestige category. Whether or not the customer will be ready to spend $400-$500 for this is quite another matter. NVIDIA has obviously realized this and allows true trilinear filtering as an option in its newest models. Well, it did not work in the latest v61.11 beta driver because of a bug... let's hope it indeed is a bug and will work again in the final driver release.

To be continued? One would assume so, because the discussion about the recently discovered brilinear filtering in the Radeon 9600 and X800 is still going full steam ahead. ATi deserves credit for the fact that the image quality of the cards is not visibly compromised by this filtering; at least no example has yet been seen of this. So far, the brilinear areas have only showed up in laborious tests. However, ATi is currently not offering true trilinear filtering with the cards mentioned above, whether adaptive or not. Because of the new filtering, the performance values of the benchmarks do not show the true potential of the X800, because the FPS values only occur due to an optimization whose details are unknown. Even the word adaptive has a bitter aftertaste. ATi has not provided information about the way the driver works and has declared numerous times that it is offering true trilinear filtering. Only since the discovery was made has ATI admitted that the filtering is optimized. Hopefully this type of adaptivity is not being used in other places in the driver .

However, slowly but surely manufacturers are moving to the point where tolerable limits are being exceeded. "Adaptivity" or application detection prevent test applications from showing the real behavior of the card in games. The image quality in games can differ depending on the driver used or on the user. The manufacturers can therefore fiddle with the driver, depending on what performance marketing needs at a given moment. The customer's right to know what he is actually buying therefore falls by the wayside. All that is left for the media is to limp along with their educational mission. The filter tricks discussed in this article are only the well-known cases. How large the unknown quantity is cannot even be guessed.

Every manufacturer decides for itself what kind of image quality it will provide as a standard. It should, however, document the optimizations used, especially when they do not come to light in established tests, as lately seen with ATi. The solution is obvious: make it possible to switch off the optimizations. Then the customer can decide for himself where his added value lies - more FPS or maximum image quality. There is no real hope that Microsoft will act to police optimization. The WHQL tests fail to cover most of them and also can be easily evaded, read: adaptivity.

Still, the ongoing discussion also has its benefits - the buyer, and perhaps, ultimately, OEMs are being sensitized to this issue. Because the irrepressible optimization mania will surely continue. However, there are also bright spots in the picture, as demonstrated by NVIDIA's trilinear optimization. We hope to see more of the same!

http://graphics.tomshardware.com/graphic/20040603/ati_optimized-13.html

Why such little drop in performance in X800 when AF applied?

http://www.beyond3d.com/forum/viewtopic.php?t=13857

What do you guys think?

Arioch
07-08-04, 10:25 AM
While I do think ATI could have been up front about this trick I can honestly say I can't tell a difference in IQ in games like Far Cry when I went from a 9800 Pro to a X800 Pro and then a X800XT PE. Some people claim to notice a difference but not in my case. I will say it would be nice if ATI gave people the option to disable the Trilinear optimization.

As for comparing it to what NV30 cards did I can't comment on that since I did not own one of those but I think this is a non-issue to me outside of the fact that ATI should have been more up front about it.

burningrave101
07-08-04, 10:44 AM
Well i think when people are running benchmarks, they should enable AF in-game whenever possible to prevent whatever optimizations ATI may have working for them in the CP.

jbirney
07-08-04, 11:35 AM
As for comparing it to what NV30 cards did I can't comment on that since I did not own one of those but I think this is a non-issue to me outside of the fact that ATI should have been more up front about it.

For me its not that big of a deal. I would like to have an option to turn it off. However since I still have yet to see a screen shot in a game of any difference (thats related to trilinear and not some other artifact) then I probably would not be able to tell if it was on or off.

This was not the case when the "brilinear" showed up with the NV3x and only on UT2003.exe back in its first version. NV was not very "up front" about their version back then...so maybe tit for tat?