by Anton Shilov , Yaroslav Lyssenko, Alexey Stepin,
09/30/2006 | 11:25 PM
UPDATE: Adding transparent texture antialiasing modes quality comparison section.
<%BANNER[article]%>There are no ideal things: all the items that we create, buy or receive as a gift have their advantages and disadvantages. When we attempt to make a choice, we always have to consider all the pros and cons, realize what advantage is the most valuable one and what disadvantage brings less inconvenience.
Like all the other things, graphics cards are not ideal: one has unique feature-set; another consumes less power; the third one offers extreme performance, but costs too lot; another one boasts with nice price/performance ratio, but produces a lot of noise and so on.
X-bit labs constantly pays attention to multiple factors, such as performance, power consumption, noise level and so on. However, one of the things that our reviews generally lacked was the image quality (IQ) comparison. This was due to the fact that at some point in the past we set up pretty similar settings for ATI and Nvidia ensuring that there were no image quality differences, and then just kept on using them without comparing the IQ head to head. But recently we have discovered that on our test settings Nvidia GeForce 7-series hardware produced considerably lower image quality when compared to ATI due to lower-quality trilinar filtering. In addition, ATI Radeon X1000 supports high-quality angle-independent anisotropic filtering. On the other hand, Nvidia has very fine 8xs antialiasing supported across the board, which would leave gamers guess, who is producing the highest quality 3D world.
Well, in this article we will try to answer this question!
We first touched upon the problem of texture filtering quality as provided by today’s graphics cards from ATI and Nvidia in our review of the ATI Radeon X1950 XTX. We found out that ATI’s solutions indeed delivered texture filtering of a higher quality but you could only see that in motion. It’s hard, if not altogether impossible, to spot the difference by comparing static images.
To show you the difference between the tri-linear filtering levels available on Nvidia’s GeForce cards, we took screenshots under ideal conditions: in 3DMark03 with enabled mip-levels highlighting.
ATI Radeon X1950 XTX vs. Nvidia GeForce 7950 GX2 Trilinear Filtering Comparison | ||
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ATI Radeon X1950 XTX, | ATI Radeon X1950 XTX, | ATI Radeon X1950 XTX, |
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Nvidia GeForce 7950 GX2, | Nvidia GeForce 7950 GX2, | |
You can see that in the Quality mode with enabled optimizations GeForce 7 series cards perform a greatly simplified filtering which looks more like a combination of bi-linear and anisotropic filtering than the classic mix of tri-linear and anisotropic filtering. There is no smoothness in the transitions between the mip-levels. This leads to the characteristic texture flickering in games and “volatile” borders of levels that you can see in motion.
The High Quality mode automatically disables the optimizations and greatly improves the quality of filtering. In this case, cards from ATI and Nvidia produce similar-looking images, although the tri-linear filtering algorithm from ATI still delivers a somewhat higher quality. It’s not because the algorithm is better. ATI’s driver just analyzes the scene and, basing on the results of the analysis, performs a more complex or simpler tri-linear filtering as necessary. This leads to an ideal tri-linear filtering as you can see when the mip-levels are highlighted. So, formally speaking, ATI offers a higher tri-linear filtering quality, but we’ll see from the following clips how things stand in practice.
In the High Quality mode, there is no more texture flickering on Nvidia cards. The transitions between mip-levels are now not as sharp as before. As you can see, the quality of tri-linear filtering is roughly the same on ATI’s Radeon X1000 and Nvidia’s GeForce 7 cards. It’s hard to tell who’s the leader here.
To check out the best anisotropic filtering ATI’s and Nvidia’s solution can provide, we used the same screenshots from 3DMark as in the test of tri-linear filtering:
ATI Radeon X1950 XTX vs. Nvidia GeForce 7950 GX2 Trilinear Filtering Comparison | ||
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ATI Radeon X1950 XTX, | ATI Radeon X1950 XTX, | ATI Radeon X1950 XTX, |
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Nvidia GeForce 7950 GX2, | Nvidia GeForce 7950 GX2, | |
Easy to see, the ATI High Quality AF algorithm is beyond competition here. It provides the best anisotropic filtering available today, which you can’t have on an Nvidia GeForce 7-series card.
Half-Life 2, ATI Radeon X1950 XTX on the left and Nvidia GeForce 7950 GX2 on the right.
The difference in anisotropic filtering quality on various angles is pointed at with arrows.
For your convinience we have included several clips too:
ATI High Quality AF ensures higher sharpness of textures at a long distance irrespective of the angle of inclination of a surface. This is most conspicuous in the first Half-Life 2 clip.
Just like in case of anisotropic filtering, full-scene antialiasing (FSAA) methods differ from GPU developer to GPU developer, as both try to offer the best speed and quality with their products. When it comes to the GeForce 7950 GX2 and the Radeon X1950 XTX, then the former has much broader choice of FSAA modes than the latter, as the model 7950 GX2 is basically an SLI-tandem, thus, supporting appropriate FSAA patterns.
The list of antialiasing patterns for the top-of-the-range graphics cards from ATI and Nvidia looks as follows:
The GeForce 7950 GX2 offers a very wide variety of FSAA modes from which users can choose an appropriate one. In fact, there are so many modes that not a lot of gamers will be able to try them all out. Moreover, there are pretty interesting 8xs and 16xs modes, which are hybrids between multi-sampling and super-sampling that offer increased quality of tiny details. Unfortunately, they are pretty much performance hungry, as you can see from performance numbers further in the article.
After checking numerous screenshots and after comparing them using The Compressonator software (even though it was designed for other purposes, it suits for comparing images perfectly), which allows pixel-to-pixel comparison easily, we can make the following conclusions:
Considering the fact that ATI and Nvidia produce roughly similar 4x FSAA, we believe that it is fair to use equal 4x settings for both.
Even though ATI Technologies was a year behind Nvidia in supporting FP16 HDR, the company has managed to offer something that the rival did not consider valuable: full-scene antialiasing along with FP16 HDR. Nvidia had a significant reason not to spend transistors on FSAA support in HDR mode back in the days of the GeForce 6- and the GeForce 7-series, as graphics boards slower than the GeForce 7800 GTX 512 would hardly achieve any decent speed with FSAA and HDR enabled even in Far Cry game.
Yet another reason for not supporting FSAA with FP16 HDR is that even now, two years after the GeForce 6 entered the scene with FP16 HDR support, there are virtually two famous games that take advantage of it: Far Cry as well as Elder Scrolls: Oblivion . Obviously, at some point in future, when more games adopt FP16 HDR, support for FSAA along with it will be compulsory, but now the technology can be enjoyed in very few games. Furthermore, ATI still has not managed to pass WHQL validation with drivers that support HDR+FSAA on Oblivion , which means that even today enabling FSAA along with HDR is not an easy procedure, as gamers have to download special non-WHQL drivers.
Elder Scrolls: Oblivion Quality with and without HDR and/or FSAA | ||
Radeon X1950 XTX | ||
No HDR | HDR | |
| 0x FSAA |  |  |
| 2x FSAA |  |  |
| 4x FSAA |  |  |
| 6x FSAA |  |  |
As you can see, Elder Scrolls: Oblivion looks remarkable with FSAA and HDR turned on. Unfortunately, we could not obtain the benchmark numbers for you to see, as performance of Oblivion with HDR+AA varies substantially, which does not allow us to present validated benchmark result: every new manual test run brings a new number.
What we can say about current state of HDR+AA support is that it is here, it provides some additional eye-candy and is generally a nice feature. However, given all the difficulties with enabling the capability, gamers should really think twice before considering this feature seriously.
Both GeForce 7950 GX2 and the Radeon X1950 XTX support antialiasing of transparent textures that can be enabled and that can benefit quite a number of games.
Both ATI and Nvidia offer their technologies to smooth edges of fences, leafs and so on. ATI calls its technology Adaptive antialiasing and offers Performance and Quality multi-sampling modes, whereas Nvidia names its feature as Transparent antialiasing offering multi-sampling or super-sampling modes. Given that we do know for sure that neither Radeon X1800 nor the GeForce 7800 graphics cards experience even a little performance degradation because of antialiasing of transparent textures, it only makes sense to examine quality of antialiasing in different implementations.
Transparent Textures Antialiasing Quality Comparison | |
Half-Life 2: Episode One | |
ATI Radeon X1950 XTX | Nvidia GeForce 7950 GX2 |
FSAA 4x, No Adaptive AA | FSAA 4x, No Transparent AA |
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FSAA 4x, "Performance" Adaptive AA | FSAA 4x, "Multi-Sampling" Transparent AA |
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FSAA 4x, "Quality" Adaptive AA | FSAA 4x, "Super-Sampling" Transparent AA |
Based on the comparison of the screenshots using the aforementioned Compressonator utility, we can conclude the following:
Please note that in case of Half-Life 2 screenshots on the Radeon X1950 XTX hardware, the fence behind Alex (a character of the Half-Life 2 game) is not rendered only on screenshots: during the game we did not experience any artifacts of this kind.
Assuming that users of high-end graphics solutions expect not only high performance but also high image quality from them, we tried to minimize the influence of texture optimizations in ATI’s and Nvidia’s drivers. We addressed both companies for advice and found out that the following settings provide the highest image quality in ATI’s driver:
Setting the Catalyst A.I. option at Standard enables the adaptive texture filtering settings, but keeps the optimization of shaders in games enabled, too. The Mipmap Detail Level option is set at High Quality by default (the slider is at its rightmost position) and provides the best quality of mip-transitions with higher sharpness of distant textures. Enabling the High Quality AF option, you turn on a high-quality anisotropic filtering algorithm that doesn’t depend on the angle of inclination of a textured surface.
The following settings provide the best image quality on Nvidia GeForce 7 cards:
So, at our graphics quality settings ATI’s products always ensure a better image quality, but bear a heavier load than Nvidia’s cards. This may look unfair, but the owner of an expensive graphics card will most probably choose the highest graphics quality. Moreover, comparing the speed of games at the old and new settings (see the results later in this review), we learned that our enabling the high-quality anisotropic filtering on ATI cards didn’t have a big effect on their performance.
In addition, we should also remember that when comparing the GeForce 7950 GX2 versus the Radeon X1950 XTX, we are comparing a $599/$649 graphics board against a $449 one.
For measuring performance of graphics cards we used our usual testbeds:
We have found out above that Nvidia GeForce 7950 GX2 has more options when it comes to antialiasing and that its 8x and higher modes offer generally higher image quality compared to ATI’s 6x. However, the quality should always be considered in conjunction to the “quantity” of frames per second.
In order to find out which FSAA modes are actually suitable from the speed point of view in the latest games, we decided to benchmark Half Life 2: Episode One as well as Elder Scrolls: Oblivion with different FSAA settings.
It is interesting to note that full-scene antialiasing is virtually free in Half-Life 2: Episode 1 in 1280x1024 resolution. In higher resolutions FSAA does reduce performance, but not dramatically. Even in 1920x1200 you will be able to play comfortably with 4x AA and high-quality angle-independent anisotropic filtering on the Radeon X1950 XTX. Obviously, the GeForce 7950 GX2 is a little bit faster, but it does not offer angle-independent AF, which is noticeable in certain cases.
Obviously, ATI’s 6x FSAA mode is a lot faster than the rest and it is hard do say that such a significant performance delta results in significant image quality difference. Nevertheless, it should be noted that both 8x and 8xs modes can be used in 1280x1024 and the former even manages to showcase nearly decent performance in 1600x1200! Unfortunately, performance with 16xs enabled is too low to consider it seriously for first person shooters.
Speaking generally and considering the results above, we can notice that there is practically no speed difference for situations with and without FSAA in the “indoor” levels of Elder Scrolls: Oblivion , which may be conditioned by the fact that performance is mainly limited by pixel shader performance, rather than memory bandwidth or the number of ROPs.
Advanced FSAA modes cannot boast with really good performance in any resolution, even though, considering nature of the title, we would suggest that up to 8xs modes can be used in 1600x1200 in the “indoor” cases of the game.
Considering the fact that modern hardware cannot provide really good performance in outdoor levels of Oblivion game, we cannot really recommend using FSAA at all, except for lower resolutions.
With the numbers above, we do not think it makes any sense to use 6x FSAA or higher in the current case.
Let’s summarize the performance graphs above:
Given that we have changed the way it is meant to be benchmarked at X-bit labs, we decided to have a look at performance difference between the models 7950 GX2 and the X1950 XTX now. We should keep in mind that along with the new settings we used the new drivers too.
As we see, Nvidia has managed to increase its performance in the game and activating more decent texture filtering did not drop the speed, unlike on ATI, where high-quality anisotropic filtering lowered performance by up to 12%.
New settings also did not change graphics board’s positioning in Call of Duty 2 game, however, we may see that disabling texture filtering optimizations on Nvidia hardware in order to get rid of texture shimmering lowers performance by as much as 15%. At the same time, speed drop for ATI is not really substantial and its lagging behind is mainly conditioned by OpenGL drivers and some other factors.
Both boards produce fantastic performance results in Far Cry and if in case of the Pier level there are nearly no difference in performance between various settings, then in case of Research level we see that Nvidia’s GeForce 7950 GX2 can lose up to 8% of performance.
When disabling texture filtering optimizations, nearly nothing happens in case of the Pier level, however, in the Research demo performance of the GeForce 7950 GX2 drops 17% amid just a tiny speed drop on the Radeon hardware from enabling high-quality anisotropic filtering.
F.E.A.R. game does not bring any significant surprises: high-quality anisotropic filtering comes for free, whereas the guaranteed lack of texture shimmering costs up to 9% of performance. Generally, the speed is pretty high and the GeForce 7950 GX2 remains nearly 20% ahead of the Radeon X1950 XTX.
Given very performance-demanding engine of the latest Tom Clancy’s Ghost Recon, we believe there is no news that improving texture filtering quality does not affect performance in any significant way. As a result, Nvidia’s GeForce 7950 GX2 is still over 30% faster compared to ATI’s Radeon X1950 XTX, even though the reason for that is not completely clear.
Performance numbers dropped insignificantly after activating high-quality AF on ATI hardware and disabling texture filtering simplifications on Nvidia’s hardware. While the gap between the rivals has generally shrunk, in the worst-case (for ATI) scenario the model X1950 XTX is still about 12% slower compared to the model 7950 GX2. Nevertheless, no matter which resolution is used, both high-end graphics cards deliver comfortable average performance with ATI hardware providing high-quality anisotropic filtering.
Both high-quality anisotropic filtering and disabling texture filtering optimizations lowered performance in Prey quite noticeably. Nevertheless, this does not change the whole picture: Nvidia’s GeForce 7950 GX2 is still ahead, even though performance of the Radeon X1950 XTX is definitely not dramatically low.
Quake 4 is another game that lowers performance because of high-quality AF noticeably. At the same time, the GeForce 7950 GX2 does not lose any significant amount of frames per second because of the lack of texture filtering optimizations.
Given that Serious Sam 2 is very dependent on performance of texture units, disabling trilinear filtering optimizations decreases performance of Nvidia hardware by up to 24%, bringing the speed of the GeForce 7950 GX2’s 48 texture units to in-line with Radeon X1950 XTX’s 16 texture units. It is interesting to note that high-quality anisotropic filtering does not cause performance declines
Disabling texture filtering optimizations and enabling HQ AF does lower performance and, perhaps, shrink the gap between ATI and Nvidia, but definitely not significantly.
It is obvious that ATI’s high-quality anisotropic filtering comes nearly for free in Splinter Cell: Chaos Theory, which cannot be said about proper trilinear filtering from Nvidia. In the best-case scenario Nvidia’s GeForce 7950 GX2 is 12% ahead of its main competitor, whereas in case of 1920x1200 resolution performance of both high-end GPUs is very similar.
The new Tomb Raider series seems to be another game where texture filtering optimizations play a giant role in improving performance of Nvidia GeForce 7950 GX2 graphics accelerator: as we see, the speed difference between different settings may be up to 19% and the dual-chip solution from Nvidia does no longer seem to be the killer of the Radeon X1950 XTX.
Neither high-quality anisotropic filtering, nor the absence of trilinear filtering optimizations affect performance significantly and with recent driver tweaks, Nvidia hardware is still noticeably ahead of ATI’s.
Meanwhile, in the outdoor scenes of Oblivion filtering quality does affect performance pretty tangibly. As a result of that, judging by minimal and average FPS, we would say that ATI’s Radeon X1950 XTX is a preferable choice compared to the GeForce 7950 GX2.
Titan Quest is another new game that demonstrates dependency on the quality of texture filtering: ATI’s high-quality anisotropic filtering costs the Radeon X1950 XTX over 15% of performance, whereas Nvidia’s product loses 47% of speed in 1920x1200 resolution without trilinear filtering optimizations. Under new settings ATI’s Radeon X1950 XTX is up to 20% ahead of the rival.
Obviously, that texture filtering has no effect on performance in flight simulators. Given Nvidia’s efficient OpenGL driver and the fact that Maddox Games uses Nvidia hardware during game development, ATI Radeon X1950 XTX can deliver only 65% of the GeForce 7950 GX2’s performance.
For some reason, increased filtering quality lowered performance of both graphics accelerators a bit in this space flight simulator. Performance of the Radeon X1950 XTX and the GeForce 7950 GX2 is nearly equal here.
Given the nature of the game, texture filtering quality does not affect performance in any case. Considering minimal FPS, we would suggest that the Radeon X1950 XTX is somewhat faster than the GeForce 7950 GX2 in resolutions higher than 1600x1200.
If ATI’s HQ AF does not really bring the speed down, Nvidia’s “shimmer-less” trilinear filtering lowers performance of the GeForce 7950 GX2 a little. Nevertheless, the latter is still up to 13% faster than the Radeon X1950 XTX.
Interestingly, but there is almost no difference between different filtering quality settings in 3DMark05. For the sake of the true, it makes sens to take a look at the results obtained in different tests of the benchmark suite.
Unlike in case of 3DMark05, we see a substantial drop in performance in 3DMark06 when we activate high-quality trilinear filtering on Nvidia GeForce 7950 GX2 hardware.
In 3DMark06 benchmark Nvidia GeForce 7950 GX2's performance drops dramatically when trilinear filtering optimisations get disabled. At the same time, the Radeon X1950 XTX's speed does not suffer from activating high-quality angle-independent anisotropic filtering.
It is very obvious that texture filtering quality does affect performance even of the very advanced graphics cards. However, it is also clear that high-quality trilinear filtering, which does not produce “shimmering” effects, on Nvidia GeForce hardware is also very performance hungry. In fact, much more speed-demanding compared to ATI’s high-quality anisotropic filtering!
Using the new test methodologies we have determined that the gap between the GeForce 7950 GX2 and the Radeon X1950 XTX is not dramatic in the vast majority of cases provided that both use high-quality texture filtering. We were also very surprised with the fact that high-quality trilinear filtering radically lowered performance in such benchmarks as Serious Sam 2 , Tomb Raider: Legend , Titan Quest , 3DMark06 and some other.
To sum up, we have to conclude the following:
When making a choice, everybody has his or her own priorities and qualities that he or she wants to obtain along with a new graphics card. You can share with us your preferences for graphics cards' features by taking part in our poll on the front-page or contacting us using our forums.
