Deeper with the GeForce 7 Series - Part 2
PCI Express x16 graphics cardsChipset GeForce 7800GT / 7800GTX 256 MB, 256 bit
This article is actually meant more as an addendum to the first part (which you can read here), where we talk mostly about transparency antialiasing performance from NVIDIA's GeForce 7 series cards. For the most part, transparency antialiasing is only really usable on old games (that does use lots of transparent textures). Newer games tend to be too much of a burden, even for the fastest GeForce 7800GTX, especially if we were to use 4x AA. We did mention that 2x AA seems to be the best compromise, but understandably image quality is not up to par to 4x AA. However, there's no way we can enabled 4x AA and 2x SSAA transparency antialiasing at the same time on the GeForce 7 series.
However, we didn't test 2xQ AA. So, in this article, we'll take another look at transparency antialiasing, particularly with 2xQ AA. From past experience, we did see that 2xQ can offer better image quality (meaning less aliasing) than 2x AA or even 4x AA (you can read the article here). So, it will be interesting to see whether or not that's true with transparent textures. After taking a look at image quality from these three modes, we also ran some performance test to see just what kind of frame rates in game we can expect with these modes.
From our suite of game benchmarks, only two games (Battlefield 2 and Serious Sam 2) exhibit both image quality and performance differences with transparency antialiasing. Both are FPS games, so we decided to look for games from other genres that made use of transparent textures for testing purposes. We chose three candidates - Age of Empires 3, Dungeon Siege 2 and Richard Burns Rally. Of the three, Richard Burns Rally responds well to transparency antialiasing the most, so we decided to enter this game to our benchmark suite. Both Age of Empires 2 and Dungeon Siege 2 does exhibit some quality improvements, but these games are very system limited, so we'll be using them as system benchmarks rather than graphics benchmarks.
Image Quality Comparison
First of, let's take a look at Serious Sam 2. Partly because of it's extensive use of transparent textures, this game will benefit the most from transparency antialiasing. On the other hand, it's also very taxing on performance. The screenshots are in this order: 4x SSAA, 2x SSAA and 2xQ SSAA.
If you look at the vines hanging off the tree, you can tell that both 4x and 2xQ is doing a better job than 2x. At the same time, if you look at the far palm tree on the left part of the image, both 4x and 2xQ also does a better job of removing aliasing - polygon wise). So, does 2xQ is the 'holy grail' of antialiasing? Not quite, if you look at the bottom of the palm tree, you can see 2xQ is still not up to par with 4x - the image still has some aliasing. You can see the same differences on both Sam's guns (the left one is more pronounced). Of course, the differences are hardly noticeable in gameplay.
Let's take a look at Battlefield 2. While 4x SSAA transparency antialiasing does incur quite a big hit with Battlefield 2, the penalty is mask by system limitations whey you're playing the game. So, you really can get away with 4x SSAA with this game. We chose a different scene for these shots, so you can tell antialiasing differences for both transparent textures and polygons.
Looks like 2xQ works even better than 4x in some parts. You can definitely still see jaggies on some of the leaves with 2x and 4x where 2xQ has less. And if you look at the power lines and the poles, you can see 2xQ does a pretty good job at removing aliasing, close or the same with 4x. But again, we can see that 2xQ still has some drawbacks - look closely at the roof of the building right in front. You can definitely see 4x doing a better job than 2x and 2xQ. These differences are minimal, but they can be noticeable in gameplay.
So, 2xQ does come pretty close to 4x AA quality. There are still differences, but you won't really notice them and the quality improvements are substantial to just 2x AA. The drawback is of course, you have to force 2xQ from the driver panel, since no game (that we know of) can make use of 2xQ from the in game menu. Forcing antialiasing mode can 'break' some games, particularly those with frame buffer effects (bloom for example).
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